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Mitigating habitat loss of western burrowing owls (Athene cunicularia hypugaea) often involves relocation from California ground squirrel (Otospermophilus beecheyi) burrows to offsite nest boxes. Naval Air Station Lemoore (NASL), Kings and Fresno counties, California, initiated this approach to displace a regionally important population from airfield grasslands. We examined monitoring data of burrowing owls and fossorial mammals at NASL to assess mitigation options. Occupied nests increased by 33 (61%), with 47 nest box installations in 1997–2001, peaked at 87 in 1999, then declined by 50 through 2013. Although ≥13 nest boxes were occupied in 2000, none were occupied in 2003–2013. Within a 43.1 ha isolated grassland monitored for 13 years, nest site reuse in ground squirrel burrows averaged only 17% between any 2 consecutive years. Compared to the average density across grassland study areas, ground squirrel burrow systems/ha numbered 43% higher within 60 m of occupied nests and non-breeding-season burrows. Vegetation clearing to restore kangaroo rat (Dipodomys n. nitratoides) habitat preceded a 7.4-fold increase in ground squirrel burrow systems and a 4-fold increase in occupied nests, but drought-induced extirpation of ground squirrels eliminated occupied nests from the 43.1 ha grassland study area. Ground cover near occupied nests averaged 58% of the mean vegetation height and 67% of the mean percentage of bare ground in the field. Both nest sites and non-breeding-season burrows occurred >60 m interior to field edges 1.4 times more than expected. Non-breeding-season burrows averaged 328 m from same-year nest sites, and only 7% of non-breeding-season burrows were also used as nest sites. Mitigating habitat loss should be made more effective by fostering natural burrow construction by fossorial mammals on patches of short-stature vegetation that is sufficiently expansive to support breeding colonies of ≥12 pairs averaging ≥60 m from the field's edge and a separation between non-breeding-season burrows and nest burrows minimally equal to mean nearest-neighbor distances among nests. [ABSTRACT FROM AUTHOR]

Wood Ducks (Aix sponsa) are secondary cavity nesters that use natural cavities and artificial nest boxes, the latter of which has been attributed to the recovery of populations across the southeastern US. Continual use of these boxes results in a buildup of bacteria, parasites, and other pathogens. To avoid the accumulation of these deleterious organisms, best management practices include the occasional removal of old nesting material (i.e., wood shavings) and replacement with fresh wood shavings. No studies have been performed on the effects of shaving material on nest box selection, nest success, and bacterial growth. We monitored 142 and 111 nest boxes in Florida and Georgia, USA, respectively, and filled a random sample with aspen or cedar shavings. We then swabbed the surface of 144 and 150 eggs during 2020 and 2021, respectively, to screen for culturable bacteria. We detected no effect of shaving type on nest box selection, nest success, or egg surface bacterial growth. We found 3-8 bacterial colony types (1-123 colony-forming units [CFU]/box) and 1-8 bacterial colony types (3-382 CFU/box) among the Georgia and Florida samples, respectively. We detected no effect from shaving type on Wood Duck reproduction or bacterial growth in the sampled nest boxes. We concluded that both shaving types are suitable nesting materials for box-nesting Wood Duck populations and the continued use of either would be a reasonable decision for managers. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Avian brood parasites depend upon locating host nests to lay their eggs. However, how brood parasites locate host nests and select the nests for parasitism remains poorly studied. Here, we examined how a non‐evicting brood parasite, the Asian koel (Eudynamys scolopaceus) were able to locate host nests in locally novel nest sites. We provided a set of novel nest sites (i.e., nestboxes, n = 100) to the common myna (Acridotheres tristis), a regular host of the Asian koel, at a field site in Central Bangladesh. We found that common myna quickly utilized the novel breeding sites (n = 99 nests across 59 boxes) and similarly, 21.2% of these nests were parasitized by the Asian koel. Unsurprisingly, none of the inactive nest boxes were parasitized, neither were empty nests of common myna (i.e., either predated or fledged clutches, thus lack of parental activity, n = 83). Our results provide an experimental demonstration of the Asian koel ability to rapidly locate nests in locally novel nest sites, potentially facilitated by close monitoring of host activity and behavior around the nest site. However, the underlying mechanisms for this rapid adjustment to novel nest sites remain unresolved. [ABSTRACT FROM AUTHOR]

We investigated the influence of conspecific and heterospecific neighbours on the reproductive success of mountain bluebirds (Sialia currucoides) and tree swallows (Tachycineta bicolor) over eight breeding seasons. The abundance of heterospecific neighbours was negatively associated with reproductive success in mountain bluebirds but positively associated with reproductive success in tree swallows during the early nesting period (i.e., hatching rate). For bluebirds, conspecific and heterospecific neighbour abundance was associated with higher reproductive success (i.e., fledging rate) during the later stages of the nesting period; the same was true for conspecific abundance for tree swallows. These findings could be explained by either positive behavioural interactions (e.g., shared defence) or by habitat quality. We found contrasting effects of nearest neighbour distance. For both mountain bluebirds and tree swallows, having a tree swallow neighbour in close proximity was positively associated with reproductive success during the early nesting period, while having a mountain bluebird neighbour in close proximity was negatively associated with reproductive success during the late nesting period for mountain bluebirds. Together, these results indicate that the effects of conspecific and heterospecific neighbours on reproductive success are species-specific and vary depending on the phase of reproduction. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Avian brood parasites depend upon locating host nests to lay their eggs. However, how brood parasites locate host nests and select the nests for parasitism remains poorly studied. Here, we examined how a non‐evicting brood parasite, the Asian koel (Eudynamys scolopaceus) were able to locate host nests in locally novel nest sites. We provided a set of novel nest sites (i.e., nestboxes, n = 100) to the common myna (Acridotheres tristis), a regular host of the Asian koel, at a field site in Central Bangladesh. We found that common myna quickly utilized the novel breeding sites (n = 99 nests across 59 boxes) and similarly, 21.2% of these nests were parasitized by the Asian koel. Unsurprisingly, none of the inactive nest boxes were parasitized, neither were empty nests of common myna (i.e., either predated or fledged clutches, thus lack of parental activity, n = 83). Our results provide an experimental demonstration of the Asian koel ability to rapidly locate nests in locally novel nest sites, potentially facilitated by close monitoring of host activity and behavior around the nest site. However, the underlying mechanisms for this rapid adjustment to novel nest sites remain unresolved.

Mitigating habitat loss of western burrowing owls (Athene cunicularia hypugaea) often involves relocation from California ground squirrel (Otospermophilus beecheyi) burrows to offsite nest boxes. Naval Air Station Lemoore (NASL), Kings and Fresno counties, California, initiated this approach to displace a regionally important population from airfield grasslands. We examined monitoring data of burrowing owls and fossorial mammals at NASL to assess mitigation options. Occupied nests increased by 33 (61%), with 47 nest box installations in 1997–2001, peaked at 87 in 1999, then declined by 50 through 2013. Although ≥13 nest boxes were occupied in 2000, none were occupied in 2003–2013. Within a 43.1 ha isolated grassland monitored for 13 years, nest site reuse in ground squirrel burrows averaged only 17% between any 2 consecutive years. Compared to the average density across grassland study areas, ground squirrel burrow systems/ha numbered 43% higher within 60 m of occupied nests and non-breeding-season burrows. Vegetation clearing to restore kangaroo rat (Dipodomys n. nitratoides) habitat preceded a 7.4-fold increase in ground squirrel burrow systems and a 4-fold increase in occupied nests, but drought-induced extirpation of ground squirrels eliminated occupied nests from the 43.1 ha grassland study area. Ground cover near occupied nests averaged 58% of the mean vegetation height and 67% of the mean percentage of bare ground in the field. Both nest sites and non-breeding-season burrows occurred >60 m interior to field edges 1.4 times more than expected. Non-breeding-season burrows averaged 328 m from same-year nest sites, and only 7% of non-breeding-season burrows were also used as nest sites. Mitigating habitat loss should be made more effective by fostering natural burrow construction by fossorial mammals on patches of short-stature vegetation that is sufficiently expansive to support breeding colonies of ≥12 pairs averaging ≥60 m from the field’s edge and a separation between non-breeding-season burrows and nest burrows minimally equal to mean nearest-neighbor distances among nests.

Controlling small mammal pests and their damage has always been a challenge for farmers. Farmers and researchers worldwide have been experimenting with deploying nest boxes to attract barn owls to their fields to remove rodent pests. While much research has focused on the potential for nest boxes and barn owls to benefit agriculture, comparatively little work has examined the impact of the practice on owls. In this study, we used a life table analysis and estimates of barn owl reproduction measured in winegrape vineyards in Napa Valley, California coupled with published estimates of survival from long-term studies in Europe to produce a demographic model of a population of barn owls using nest boxes. We then examined how manual perturbations of survival and reproductive rates affect whether the modeled population is stable, increasing, or decreasing. Based on our empirical estimate of reproductive success and literature-sourced estimates of survival, the population appears to be growing. Across all scenarios in which we adjusted survival, there were only five that resulted in the population declining. All scenarios that resulted in population decline occurred when survival was reduced for all ages simultaneously or for adult survival independently. There were no scenarios in which lambda dropped below 1 when modifying reproductive success independent of survival. These results are important for practical pest-management reasons, as nest boxes cannot be part of a successful long-term integrated pest management (IPM) plan if they are reliant on continual immigration of adult owls from other source populations to offset mortality. A thorough examination of ecological traps should be conducted using additional information on habitat selection and reproduction in natural nest sites.

Noise pollution can degrade the behavioral, physiological, and psychological health of humans and other creatures. We used breeding pairs of Eastern Bluebirds ( Sialia sialis ) to assess behavioral and reproductive responses to both chronic roadway noise and experimental intermittent playbacks of construction noise. Active nests in boxes placed near and far from large roads were randomly assigned as treatments or controls for experimental playbacks during incubation. Using temperature signatures from iButtons placed within nest cups we quantified certain female incubation behaviors (# and length of bouts, # of small temperature fluctuations, and total warming minutes per day) and hatching success was recorded for 40 nests in spring of 2019. Nests in quiet areas that received no additional playback treatments of construction noise had markedly higher nest success than any exposed to noise. Nests exposed to chronic traffic noise only, and quiet nests that received 3–4 days of construction noise had the lowest hatching success. Females in traffic-quiet nests increased restlessness (small temperature fluctuations) and experienced decreasing hatching success as the number of days of construction noise playback increased. Thus, birds choosing either quiet or noisy boxes had contrasting responses to bouts of construction noise. Other female incubation behaviors we could detect were unaffected by noise but changed in expected ways with seasonal progression. In sum, both types of noise can decrease hatch rate, but with intermittent noise this is likely due to female restlessness, or too many small drops in temperature to maintain optimal embryo development.

Abstract Artificial habitat for cavity nesting birds can provide excellent opportunities for research and conservation efforts but may expose species to the negative impacts of warming ambient temperatures with climate change. Artificial nest boxes have been successfully used to monitor the breeding activity of the Cassin's auklet (Ptychoramphus aleuticus), a small burrow‐nesting seabird, on Southeast Farallon Island (SEFI) since 1971. Mean monthly ambient air temperatures on SEFI during the summer months have increased at an annual rate of roughly 0.03°C from 1971 to 2022, along with an increase in the number of extreme heat days and average maximum temperature, confirming a warming trend at this seabird colony. Given a projected increase in global temperature, we assessed the effectiveness of traditional wooden nest boxes vs. newer ceramic modules at buffering external ambient air temperatures in normal and extreme heat days across a gradient of microclimates on SEFI. Results from fitting linear mixed effects models indicated that, on average, internal temperatures of wooden and ceramic nests (of comparable size and shape) exhibited similar rates of deviation from ambient air temperature of approximately 0.15°C, even during extreme heat events. Ceramic modules did keep nest chambers cooler by approximately 1.2°C than wooden boxes during extreme events at the warmer, drier southern location of the island. Our results can help guide future efforts to design artificial nests that can effectively provide habitat for seabirds as ambient temperatures increase.

According to the alternative prey hypothesis (APH), the temporal synchrony in population fluctuations of microtine rodents and other small herbivores in boreal areas is caused by generalist predators with numerical and functional response to microtines, leading to an increased predation of prey alternative to microtines in the low phase of the microtine population fluctuations. The tree‐climbing pine marten (Martes martes) is a food generalist that includes bird eggs among its alternative prey, also eggs of the cavity‐nesting common goldeneye (Bucephala clangula). We used long‐term data to test whether pine marten predation of goldeneye eggs in nest boxes varied as predicted by the APH. As a measure of microtine abundance at the time of nesting, we applied two measures. First, for goldeneye nests located <40 km from our microtine trapping site, we applied the trapping index of microtine rodents. Second, to also use data from nests located >40 km from our microtine trapping site, and from nests in years when trapping was not conducted, we used two proxies for the microtine abundance: whether boreal owls (Aegolius funereus) nested in any of our boxes <40 km from each goldeneye nest and the average clutch size of these boreal owls. The probability of predation of a goldeneye nest was independent of the microtine trapping index and independent of the proxies for microtine abundance. However, it increased with cavity age, taken as the number of nesting seasons elapsed since the actual nest box was installed, and declined with distance from habitat with forest canopy. The effect of cavity age confirms that the long‐term spatial memory of pine marten is an important factor in the pattern of its predation on nests in tree cavities. [ABSTRACT FROM AUTHOR]

Communal nesting behaviour of small mammals is thought to function mainly as a method of thermoregulation. However, this behaviour is also observed during the non‐winter season when there are no obvious thermoregulatory benefits. Siberian flying squirrels (Pteromys volans) nest communally during the non‐winter season. This may facilitate mating, but other functions such as thermoregulation have not been sufficiently studied. Therefore, we examined whether communal nesting of P. volans during the non‐winter season plays a role in thermoregulation in addition to mating. In the event that communal nesting in the non‐winter season has any function other than mating, we expected an increase in non‐mating groups consisting of only‐males during the nurturing period (duration of mother squirrel and cubs living together) because females rearing their young do not participate in communal nesting. In Obihiro, Hokkaido, Japan, during the non‐winter season (May–October) between 2019 and 2021, we captured P. volans in 252 nests by using nest boxes. The occurrence of male‐only groups showed a tendency to increase during the nurturing period. Moreover, the number of mixed‐sex groups increased between August and October each year; these changes in communal nesting during the non‐winter season were unrelated to the variation in air temperature or precipitation. These results suggest that during the non‐winter season, communal nesting of P. volans is related to reproductive behaviour. Additional studies are needed to determine how communal nesting during the non‐winter season enhances the reproductive success of male and female P. volans. [ABSTRACT FROM AUTHOR]

Some secondary cavity-nesting birds use nest material to cover their eggs when they are out foraging during the egg-laying stage. Egg covering presumably helps regulate nest temperature and/or prevents predation or parasitism. A recent study suggested that egg covering might prevent nest usurpation and therefore, we set up nest boxes with three different treatments to test this hypothesis: bottom of the nest box covered with moss containing two eggs covered with moss (type A); floor of the nest box covered with moss and two eggs exposed on top of the moss (Type B); and bare floor of the nest box, with two eggs added (Type C). The results showed the lowest egg predation rates in Type A nest boxes, which was significantly lower than those in type C boxes; the proportion of maritime striped squirrels (Tamiops maritimus), first appearing in the three types of nest box was not significantly different; however, the rate of first entry into Type A was significantly lower than that into Type C boxes. The rate of first entry and the time the squirrels spent in Type A boxes were significantly lower and shorter than those in Type C boxes. Our results suggest that the egg-covering behavior of secondary cavity-nesting birds delayed the entry of nest competitors and accelerated the departure of nest encroachers from the nest, thus provided experimental evidence for the usurpation hypothesis. Significance statement: Several non-mutually exclusive hypotheses have been proposed to explain the function of egg covering by bird species. The present study showed that egg covering by secondary cavity-nesting birds delayed the entry of maritime striped squirrels and accelerated the departure of nest encroachers from the nest, suggesting that egg covering might reduce the cost of nest defense for birds and thus prevent nest encroachment by other species. We provided experimental evidence for the new hypothesis proposed by Slagsvold and Wiebe (2021a) that egg-covering behavior of birds deters nest encroachers from easily entering unfamiliar, poorly lit cavities due to fear, thereby effectively preventing nest usurpation by squirrels. [ABSTRACT FROM AUTHOR]

Understanding patterns of habitat use is required to conserve species and to manage their habitats. I used detections of 156 individual eastern pygmy-possums (Cercartetus nanus) within artificial cavities to investigate habitat use across 18 ha of a woodland–heathland mosaic. Detection of breeding females was highest in autumn (March to May) and winter, during the flowering period of Banksia ericifolia. Detection was over two times higher in woodland compared with heathland. This pattern was not influenced by variation in flowering or hollow abundance, which were equivalent across the two habitats. Protection from the weather may drive this pattern. Adult males were detected most frequently in autumn, coinciding with the beginning of female reproduction. They were detected equally in woodland and heathland. Why detection was lower in winter and spring is unclear but may arise from female aggression, forcing males to use natural shelters away from lactating females. Subadults were detected most frequently in spring and summer, coinciding with independence and dispersal. Subadults preferred woodland, reflecting where they were reared. This study has provided new insights into the behavioural ecology of this species, but further studies are needed to better understand how foraging and breeding influence shelter site use. I used detections of 156 individual eastern pygmy-possums within artificial cavities to investigate habitat use across 18 ha of a woodland–heathland mosaic. Differences were observed among breeding females, adult males and subadult pygmy-possums in the season of highest detection. Breeding females and subadults had higher detection in woodland compared with heathland. [ABSTRACT FROM AUTHOR]

Urban noise can disrupt avian communication networks, resulting in reduced communication among individuals. Mountain chickadees alter their vocalisations in areas of high ambient noise; however, it is unknown how audible their signals are within the nest cavity, where the female remains during dawn signalling. To test the relative audibility of songs within the nest box of urban and rural chickadees, we conducted a playback experiment directed at empty nest boxes using an autonomous recording unit above the box with external microphones and an internal microphone inside the nest box. We placed a speaker 25-75 m from the nest box and played two playback files of mountain chickadee songs – one with added noise and one without. Songs had a higher signal-to-noise ratio (SNR) in rural habitats and in 'Without Added Noise' treatments, however, SNR decreased with increasing distance from the nest box. The lower frequency song notes had a lower SNR inside the nest in both treatment types. As expected, noise and distance resulted in decreased SNR of chickadee songs within the nest cavity. These findings suggest a possible constraint in urban birds requiring them to reduce their distance from the nest to ensure audibility to the female while in noise. [ABSTRACT FROM AUTHOR]

Both artificial and natural regeneration of oaks strongly depend on the quantity and quality of the acorn crop, which show high year-to-year variation. The volume of the acorn crop is influenced by many factors including biotic and abiotic effects. The quality (i.e., germination ability, nutrient reserves) of acorns can be decreased by carpophagous insect and fungal pathogen damage or by inadequate weather conditions. Defoliating insects (caterpillars, sawfly larva, etc.) can significantly decrease the acorn crop as well. The most important predators of the defoliators are insectivorous birds during their nesting period. However, in the oak forests of the northern Hungarian mountains, there is a shortage of natural nesting holes. The main aim of our study was to artificially increase the number of the available nesting holes by nest boxes and to maximize the number of breeding insectivorous birds and register the direct (Lepidoptera densities) and indirect (acorn crop quantity and quality) effects of their presence. We found only slight effects on Lepidoptera densities, so we failed to demonstrate a direct effect in the relatively low time frame of our study. But, we could show the indirect positive effect of increased predation on the health state of the acorn crop, resulting in higher seedling densities, which may improve the natural regeneration potential of sessile oak. This result supports the outstanding importance of natural nesting holes in broadleaved forests. [ABSTRACT FROM AUTHOR]

Many bird species have advanced their first egg dates in response to recent milder winters and increases in spring temperatures. Tree Swallows ( Tachycineta bicolor ) begin egg laying earlier in warmer springs at most, but not all, study sites. We examined whether Tree Swallows that nested in boxes in west Michigan responded to an increase in spring temperatures from 1993 to 2018 by advancing their first egg dates. May, but not April, mean daily temperatures got significantly warmer from 1993 to 2018. We found that the first egg dates, but not mean first egg dates, of both second year (SY) and after second year (ASY) females got earlier between 1993 and 2018. The first egg dates of SY females did not get earlier in response to warmer April or May temperatures but got earlier when there were more days in May with measurable rain. The first egg dates of ASY females got earlier with warmer April and May temperatures. Overall, the relationships between weather conditions and first egg dates of both SY and ASY females were complex and varied yearly. The climatic conditions that influence Tree Swallow first egg dates are complex because stochastic rain and wind conditions interact with air temperatures to affect the availability of the aerial insect prey of swallows thereby influencing the ability of females to begin egg laying.

Abstract According to the alternative prey hypothesis (APH), the temporal synchrony in population fluctuations of microtine rodents and other small herbivores in boreal areas is caused by generalist predators with numerical and functional response to microtines, leading to an increased predation of prey alternative to microtines in the low phase of the microtine population fluctuations. The tree‐climbing pine marten (Martes martes) is a food generalist that includes bird eggs among its alternative prey, also eggs of the cavity‐nesting common goldeneye (Bucephala clangula). We used long‐term data to test whether pine marten predation of goldeneye eggs in nest boxes varied as predicted by the APH. As a measure of microtine abundance at the time of nesting, we applied two measures. First, for goldeneye nests located 40 km from our microtine trapping site, and from nests in years when trapping was not conducted, we used two proxies for the microtine abundance: whether boreal owls (Aegolius funereus) nested in any of our boxes

Most populations of the European Pied Flycatcher Ficedula hypoleuca are decreasing. Different reasons for the decline are discussed, including biotic interactions and climate change. It is evident that many studies have been conducted in populations depending completely on nest boxes, but the influence of this artificial support on population dynamics is not well understood. We investigated the population dynamics of the Pied Flycatcher in the Kottenforst, an old-growth forest in western Germany, using recent data as well as historical records. We also determined the proportion of pairs breeding in nest boxes vs. natural nesting places. Specifically, we quantitatively analysed forest structure around tree holes occupied by the Pied Flycatcher. We found a continuous increase in population size since its establishment in the 1960s, which contrasts with overall long-term population trends in Europe as well as the regional trend. Whereas importance of nest boxes decreased over recent years, the majority of pairs are occupying tree holes for breeding, which are abundant in the richly structured, open old-growth forest. This forest structure seems to be optimal for the Pied Flycatcher since it allows flying insects to be hunted close to the nest. Finally, we discuss how forest structure and age as well as tree hole and insect availability may determine population trends of the Pied Flycatcher and highlight the importance of long-term studies. —Abrahamczyk, S., Grimm, J., Fehn, M. & Stiels, D. (2023). Long-term decoupling of a local population trend of the European Pied Flycatcher Ficedula hypoleuca from nest box abundance indicates the importance of old-growth forest. Ardeola, 70: 185-200. La mayoría de las poblaciones de papamoscas cerrojillo Ficedula hypoleuca están disminuyendo. Se discuten diferentes razones de este declive, entre ellas las interacciones bióticas y el cambio climático. Es evidente que se han realizado muchos estudios en poblaciones que dependen completamente de las cajas nido, pero no se conoce bien la influencia de este soporte artificial en la dinámica poblacional. Hemos investigado la dinámica poblacional del papamoscas cerrojillo en Kottenforst, un bosque antiguo del oeste de Alemania, utilizando datos recientes y registros históricos. También determinamos la proporción de parejas que crían en cajas nido frente a lugares de nidificación naturales. En concreto, analizamos cuantitativamente la estructura forestal en torno a los huecos de los árboles ocupados por el papamoscas cerrojillo. Encontramos un aumento continuo del tamaño de la población desde su establecimiento en la década de 1960, lo que contrasta con las tendencias poblacionales generales a largo plazo en Europa, así como con la tendencia regional. Mientras que la importancia de las cajas nido ha disminuido en los últimos años, la mayoría de las parejas ocupan agujeros en los árboles para criar, que son abundantes en el bosque antiguo, abierto y ricamente estructurado. Esta estructura forestal parece ser óptima para el papamoscas cerrojillo, ya que permite cazar insectos voladores cerca del nido. Por último, discutimos cómo la estructura y la edad del bosque, así como la disponibilidad de huecos en los árboles y de insectos, pueden determinar las tendencias poblacionales del papamoscas cerrojillo y destacamos la importancia de los estudios a largo plazo.—Abrahamczyk, S., Grimm, J., Fehn, M. y Stiels, D. (2023). La desvinculación a largo plazo entre la tendencia poblacional local del papamoscas cerrojillo Ficedula hypoleuca y la cantidad de cajas nido indica la importancia del bosque maduro. Ardeola, 70: 185-200. [ABSTRACT FROM AUTHOR]

Today, some environmental problems have reached such severe proportions that it is no longer enough to recognise them, but environmentally friendly solutions must be used to reduce them. The reduction in the area of natural forests of native species is causing problems in several ways. This research aimed to highlight how environmental, conservation and economic interests can be reconciled. In addition to natural forests, wood energy plantations are becoming increasingly important. Energy import dependency is a problem for most countries, for which wood energy plantations can partly offer an alternative. Native forests can be protected, and their area increased where possible. Meanwhile, energy plantations can be established in areas with low agricultural productivity. In this experiment, I studied a plantation of Pedunculate Oak (Quercus robur), a Black Locust (Robinia pseudoacacia) and a Paulownia (Paulownia Shan Tong). I selected burrowing birds and ground-dwelling arthropods as indicator groups. I did this by establishing a nesting colony and soil trapping. I wanted to demonstrate that, in addition to natural forests, wood energy plantations have a role not only in economic terms but also in maintaining certain animal groups. Soil trapping tests were carried out in all three tree plantations. The obtained results showed that in the Paulownia plantation, the occupancy rate of nest boxes was almost 100%, while in the Black Locust plantation it was around 30%. Among the species that occupied the nesting sites, the Common Starling (Sturnus vulgaris) and the Eurasian Tree Sparrow (Passer montanus) were more abundant, while Great Tit (Parus major) was present in the Black Locust plantation. These are opportunistic species for which nesting opportunity is the most important factor, since their feeding area (in the case of the Common Starling and the Eurasian Tree Sparrow) is not typical of the nesting area. The soil trap investigations show that there are no signif icant differences in the composition of the arthropod group (beetles, spiders) in the study areas. [ABSTRACT FROM AUTHOR]

American Kestrel (Falco sparverius) populations have been declining in North America during recent decades and potential causes, including climate change, currently are under investigation. Many studies of migratory birds have demonstrated the effects of climate change, including changes in local weather conditions and the increase in extreme weather, but the relationship between local weather and kestrel ecology in the northeastern United States has received little attention. We examined the relationship of local weather conditions and kestrel breeding performance in northwestern New Jersey between 1996 and 2016. We also obtained temperature, rainfall, and snowfall data from weather stations within or adjacent to our study area. We did not detect significant changes in climate over the study period, but we did find significant associations between local weather conditions and kestrel breeding performance. Warmer temperatures during the breeding season were significantly correlated with earlier nesting, and early nesting had significant positive correlations with clutch size, hatching rate, nestling survival, and nesting success (raising at least one young to fledging). We did not detect a significant relationship between rainfall and nesting variables, but snowfall during autumn was strongly related to kestrel breeding performance the following year. Compared to years when there was no snowfall in our study area the preceding autumn, kestrels breeding in years following autumn snow had significantly smaller clutches, lower hatching rates, lower nestling survival rate, and lower nesting success. Kestrels in our region are partial migrants; first-year birds generally migrate to southern wintering grounds while older birds may remain in the region, presumably in response to local conditions. We suggest that substantial snow during autumn may drive a larger percentage of adults to migrate south, as indicated by the greater number of kestrels counted at representative autumn hawk watch sites during years with substantial autumn snow. Our study concludes that variations in local weather conditions throughout the year can affect the breeding performance of American Kestrels, whether or not they are associated with climate change. [ABSTRACT FROM AUTHOR]

The American Kestrel (Falco sparverius), a small, cavity-nesting falcon that breeds across most of North America, is experiencing an apparent population decline across much of the United States that has yet to be sufficiently explained. With landscape change as a potential factor, the association of landscape composition with kestrel reproduction may assist not only in managing declines but also in improving the effectiveness and efficiency of nest box programs, which can bolster local populations and support monitoring and research efforts. We monitored 163 unique American Kestrel nest boxes over a 12-yr study period (2008–2019) in western Virginia to investigate the factors influencing kestrel reproductive success and we documented relatively high rates of both box occupancy (80%) and nest success (78.9%). In a study area dominated by both high- and low-intensity agriculture, we focused on identifying patterns in land cover composition that may limit reproductive success and associated each box with land cover composition metrics at four spatial scales. Generalized linear mixed models indicated nest boxes with a lower proportion of developed land within 500 m, and a higher proportion of crops and pasture/hay within 3 km were more likely to be occupied by kestrels. Although probability of kestrel nest success increased with reduced proportions of developed land within 100 m, the primary factors influencing success were clutch initiation date and the presence of European starlings (Sturnus vulgaris), with earlier nesting and the absence of starling activity resulting in higher nest success. Overall, cover-type associations with nest success and box occupancy were not strong and establishment of nest boxes in targeted kestrel habitat, while likely maximizing reproductive output, limits research opportunities to identify critical land cover thresholds for the species. [ABSTRACT FROM AUTHOR]

We monitored a population of American Kestrels (Falco sparverius) nesting in boxes at the northern extent of the kestrel range (between 66° and 68°N) in the Alaskan Arctic, 2002–2021. There was no significant trend in occupancy during the study period but yearly variation in occupancy was high (range = 17–70%). Occupancy rate was positively related to the lowest temperature recorded in May (7–20°C). The mean estimated clutch initiation date was 16 May ± 6 d; we observed a slight but significant trend for later clutch initiation (4 d) during the study period. Kestrel clutch size averaged 4.7 ± 1.0 (range = 1–7), brood size averaged 4.6 ± 0.8, and the mean minimum number of young fledged/successful pair was 4.9 ± 0.4. Clutch and brood sizes remained stable from 2002–2021, with no significant trend. Nest failure was low (16%). We report a late nesting and possible double brooding attempt in 2018, suggesting a possible response to the warming trend (2002–2021) in average temperatures at the end of the normal nesting season. [ABSTRACT FROM AUTHOR]

Birds select suitable nest sites for breeding to ensure their own and offspring's survival; however, they inevitably suffer some potential predation risk. We studied the breeding ecology of Daurian redstarts (Phoenicurus auroreus) by providing nest boxes for their breeding from March to August of 2022. We recorded the predation of both Daurian redstarts eggs or nestlings by Oriental magpie‐robins (Copsychus saularis) and tree sparrow (Passer montanus). Oriental magpie‐robin were recorded attacking a feeding female adult and depredating nestlings. After the nestling predation event, the Daurian redstarts abandoned the nest. This video evidence provide a better understanding of the potential predators of cavity‐nesting birds. [ABSTRACT FROM AUTHOR]

To mitigate the economic and environmental costs of rodent pests, winegrape producers in Napa Valley, California, have installed nest boxes to attract barn owls to their properties, but their effectiveness to control rodent pests in vineyards has not yet been thoroughly tested. A rigorous estimate of the number of rodents that barn owls remove from the landscape is a necessary step, and this study aimed to produce estimates of rodent removal and prey species composition by using remote nest box cameras. Results indicate that each barn owl chick received 170.2 ± 8.92 rodents before dispersing from the nest box. Combined with the average number of chicks fledged (3.62 ± 1.40), this finding indicates adults deliver on average 616 rodents per nest box, with low and high estimates ranging from 358 to 899 rodents. With conservative assumptions of owl survival and consumption during the non-breeding season, we estimate a barn family could remove 3,466 rodents in a full year (estimates ranged from 1,821 to 7,563). An analysis linking videography to owl telemetry data suggested that 43% of rodents killed were taken from vineyard habitat, which nearly matches the availability of vineyard habitat around the monitored nest boxes (46%). In contrast, more prey were captured from riparian habitat and fewer from grassland habitat than expected given their availabilities. Our results suggest barn owl nest boxes could contribute meaningfully to integrated pest management. Future research should involve rodent surveys in vineyards without and without barn owl nest boxes.

Migratory organisms can be vectors of parasitic host organisms that can then be transported along seasonal migratory journeys and spread across continents. Ornithophilic nidicolous ticks (e.g. soft ticks) include species responsible for the transmission of pathogens and bacteria, thus representing a health problem not only for wild species that are directly parasitized, but also for those that share the same environments or reproductive sites with them. In this regard, artificial nests for birds may turn out to be site-sources of parasites. Here, we document the occurrence of different life stages of Argas persicus ticks in nest boxes of wild birds in a natural area (not associated with poultry activities) of central coastal Italy (Maremma Regional Park, Tuscany). Between 2018 and 2022, 168 ticks were collected from nest boxes occupied by different secondary cavity-nesting birds, such as European rollers Coracias garrulus and scops owl Otus scops. Ticks were analysed morphologically, and selected specimens were also identified by mitochondrial ribosomal 16S (16S) subunit gene to ascertain their taxonomic status. All ticks were identified as Argas persicus. This finding not only suggests that this tick species has formed a viable population in this Italian region, but also further confirms the previously doubtful natural origin of the species at country level and sheds new light on its underestimated and little investigated distribution. Possible pathways of introduction and its potential impacts on local avian community are discussed. [ABSTRACT FROM AUTHOR]

Abstract Birds select suitable nest sites for breeding to ensure their own and offspring's survival; however, they inevitably suffer some potential predation risk. We studied the breeding ecology of Daurian redstarts (Phoenicurus auroreus) by providing nest boxes for their breeding from March to August of 2022. We recorded the predation of both Daurian redstarts eggs or nestlings by Oriental magpie‐robins (Copsychus saularis) and tree sparrow (Passer montanus). Oriental magpie‐robin were recorded attacking a feeding female adult and depredating nestlings. After the nestling predation event, the Daurian redstarts abandoned the nest. This video evidence provide a better understanding of the potential predators of cavity‐nesting birds.

Passerines are the most threatened by predators during the nesting period. According to the results of visual observations conducted during 2019–2021 in forests of north-eastern Ukraine, a high proportion of bird nests destructed by the pine marten (Martes martes) in artificial nest boxes was revealed. The impact of the predator was assessed according to the following signs: the front wall of the nest box fell off, the bird’s nest was destroyed and torn, traces of claws on the front wall of the nest box, fragments of feathers and bones of the bird found nearby. In the pine forest of the Hetmansky National Nature Park near Kamenka village, the share of destroyed by the pine marten nests increased during 2019–2021 from 15.6% to 36.0% and 45.2%, respectively. In a forest of the Homilshansky Lisy National Nature Park near Zadonetske village, the largest share of nests ruined by the forest marten was 51.1% in 2020 and 33.3% in 2021. Cases of predation predominated in net boxes with nests of Parus major in the third decade of May (21.05–31.05)—15.9% (n = 47) in the Homilshansky Lisy National Nature Park; F. albicollis in the first decade of June (01.06–10.06)—19.1% (n = 43) in the Hetmansky National Nature Park near Kamenka village. In general, the results indicate an increase in the destruction of nests in nest boxes by the pine marten in the first decade of June (01.06–10.06) and in the first or second decade of July (01.07–20.07) for most bird species, including Parus major, Ficedula albicollis, Phoenicurus phoenicurus, Ficedula hypoleuca, and Erithacus rubecula. At the end of the third decade of February and during March, an inspection of nest boxes showed that a large number of adults of Parus major spend the night in the nest boxes. At the same time, in 2021, their share was 15% (n = 100), of which 10% became victims to the forest marten in the Homilshansky Lisy National Nature Park near Zadonetske village. In the territory of Hetmansky National Nature Park near Kamenka village, in 2020, Parus major was also the main victim of the pine marten, with a share of 5.0% (n = 120). Among the adult birds in the nest boxes that did not form breeding pairs or of which, eventually, the male or female died, the inspection of nest boxes also revealed cases of predation by the pine marten.

The Barn Owl (Tyto alba) belongs to iconic species of the Czech countryside. During the 20th century the species declined dramatically and disappeared from many regions, especially at medium altitudes. Today it is listed in the National Red List of Threatened Species as critically endangered. The decline is caused by many factors. Intensification of agriculture and loss of safe breeding sites are the most crucial. In Central Europe, the Barn Owl feeds mainly on the Common Vole (Microtus arvalis) and the prey population cycle affects reproductive success of the owls. The Barn Owl helps in agricultural pest management. It requires diverse farmland habitats with lots of tree lines, hedgerows, old orchards and ditches. Such fine-scale landscape patchwork has a stable water regime, supports species diversity and also attracts people for free time activities. The charismatic Barn Owl with its role in crop protection, dependency on farms for breeding and preferences for diverse agricultural habitats is an ideal umbrella species for countryside wildlife conservation. In spite of all these facts, there is no official national or local action plan for the Barn Owl conservation in the Czech Republic. This paper summarises the most important knowledge about the Barn Owl which is relevant for systematic conservation effort and proposes the rules for such activities at the national or local scale. [ABSTRACT FROM AUTHOR]

The European roller (Coracias garrulus) is an endangered species whose breeding in Serbia depends almost entirely on nest boxes. The aim of the present study was to assess the influence of prey availability and foraging habitat characteristics on nest-box occupancy and breeding parameters. Data from 20 roller foraging sites over 5 breeding seasons were used in a set of linear regression models to evaluate which factors affect the diversity and biomass of roller prey, as well as nest-box occupancy and breeding parameters. Our analyses revealed that prey availability parameters were significantly affected by the grazing regime and biophysical parameters. An area under grassland negatively affected nest-box occupancy, clutch size and fledging success. In contrast, grazing intensity showed positive effects. Although grazing negatively affected prey diversity and quantity, it potentially increased the likelihood of a successful hunt by forming short vegetation. These results indicate that the habitat characteristics linked to the ability of the species to hunt successfully should be considered when installing nest boxes as a part of the broader management of roller breeding sites. Furthermore, nest-box installation in open agricultural habitats other than grasslands should be considered in the conservation strategy for the species in Serbia.

Many winegrape farmers have installed nest boxes to attract barn owls to manage rodent pests, but this prospect has not been rigorously examined. We provide a brief history and context of the use of, and research on, barn owl nest boxes in California vineyards, and we suggest six key research questions necessary to better evaluate the capacity for barn owls to help control rodent pests: 1) How and where should boxes be placed to enhance barn owl occupancy? 2) How much are owls hunting in vineyards versus surrounding habitat? 3) How many rodents do they remove from vineyards? 4) Do they remove enough to meaningfully reduce rodent numbers and decrease crop damage? 5) What can farmers do to maximize hunting on their vineyards? and 6) What factors influence farmers’ decisions to use or not use nest boxes? Some work has recently been aimed at questions 1-3, but additional work is needed to confirm and generalize those results, and questions 4-6 remain, to date, unanswered. We suggest a research agenda to help address those unmet needs and advance our understanding of the potential for and application of barn owl nest boxes for pest management in winegrape vineyards.

In order to potentially reduce use of environmentally damaging rodenticides, integrated Pest Management (IPM) for rodents, or Ecologically Based Rodent Management (EBRM), proposes a more sustainable management approach using strategies informed by an increased understanding of rodent population and community ecology, including interactions with important predators, such as raptors. Nest boxes and perches can encourage raptor presence in agricultural areas and potentially enhance the regulatory ecosystem services provided by raptor predation of agricultural pests. To assess this idea, we studied American kestrels (widespread, generalist predators that readily use nest boxes) in a fruit-growing region of northwestern Michigan. The most common mammal prey in the diets of these kestrels from 2013 through 2016 were voles, which are considered the most important rodent pests in temperate fruit orchards. We utilized live trapping to measure small mammal abundances and activity during the summer at sites with and without active kestrel nest boxes; furthermore, we utilized camera trapping to measure small mammal presence during the winter, when damage to trees is most likely. As predicted, small mammal abundance and activity was lower at orchards with active kestrel boxes and at orchards that had been more recently mowed; however, these differences did not carry over as differences in winter presence in orchards. Our sampling demonstrated that voles were absent from orchards during both summer and winter, which suggests that orchards offer insufficient cover except under certain conditions, such as sustained snow cover. Instead, mice were the most abundant small mammals in most orchards during the summer and were also present during the winter. More evidence is therefore needed to determine the extent of orchard damage attributable to Peromyscus spp. and whether indirect effects of kestrels on Peromyscus spp. may reduce damage. We provide recommendations for future research on the effects of raptor predation in orchards.

Abstract Bespoke (custom‐built) Raspberry Pi cameras are increasingly popular research tools in the fields of behavioral ecology and conservation, because of their comparative flexibility in programmable settings, ability to be paired with other sensors, and because they are typically cheaper than commercially built models. Here, we describe a novel, Raspberry Pi‐based camera system that is fully portable and yet weatherproof—especially to humidity and salt spray. The camera was paired with a passive infrared sensor, to create a movement‐triggered camera capable of recording videos over a 24‐hr period. We describe an example deployment involving “retro‐fitting” these cameras into artificial nest boxes on Praia Islet, Azores archipelago, Portugal, to monitor the behaviors and interspecific interactions of two sympatric species of storm‐petrel (Monteiro's storm‐petrel Hydrobates monteiroi and Madeiran storm‐petrel Hydrobates castro) during their respective breeding seasons. Of the 138 deployments, 70% of all deployments were deemed to be “Successful” (Successful was defined as continuous footage being recorded for more than one hour without an interruption), which equated to 87% of the individual 30‐s videos. The bespoke cameras proved to be easily portable between 54 different nests and reasonably weatherproof (~14% of deployments classed as “Partial” or “Failure” deployments were specifically due to the weather/humidity), and we make further trouble‐shooting suggestions to mitigate additional weather‐related failures. Here, we have shown that this system is fully portable and capable of coping with salt spray and humidity, and consequently, the camera‐build methods and scripts could be applied easily to many different species that also utilize cavities, burrows, and artificial nests, and can potentially be adapted for other wildlife monitoring situations to provide novel insights into species‐specific daily cycles of behaviors and interspecies interactions.

Context: Supplementary shelters for hollow-dependent fauna, such as timber or plywood nest boxes, have much drier and less thermally insulated cavity microclimates than do natural tree hollows. Hollow-dependent endotherms can experience hyperthermia and dehydration when occupying poorly insulated nest boxes during extreme heat. Aims: We investigated the effectiveness of three different types of artificial hollows in buffering hollow-dependent birds and mammals against hyperthermia and dehydration during extremely hot summer weather (ambient air temperatures >40°C). Methods: We recorded microclimate (temperature and relative humidity) data inside (1) chainsaw hollows carved into live trees, (2) log hollows, and (3) plywood nest boxes, during extremely hot weather events in Australia in December 2019–January 2020 (austral summer). We quantified temporal variation in microclimates inside the different supplementary shelters relative to ambient conditions and used statistical models to evaluate the effects of different factors (wall thickness and solar exposure) on internal microclimates. Key results: Microclimates inside chainsaw hollows were significantly different from those in log hollows and nest boxes, remaining >16°C cooler and 50 percentage points more humid than ambient conditions when daytime air temperatures reached 45°C. In comparison, nest boxes closely tracked ambient conditions throughout the day. Log hollows had an intermediate microclimate profile, getting warmer and drier than chainsaw hollows during the day, but remaining cooler and more humid than nest boxes. Conclusions: Our results showed that artificial hollows more effectively mimic the stable microclimates inside naturally occurring hollows if placed inside the tree (e.g. carved into the tree trunk of live trees), rather than attached to the outside. Implications: The chainsaw hollow design we tested could provide microclimate refugia that reduce the risks of hollow-dependent wildlife experiencing either hyperthermia in regions with hot summer climates, or hypothermia in areas with cold winters. We encourage managers to consider incorporating chainsaw hollows into existing nest box programs to provide fauna with well insulated microclimate refugia. Hollow-dependent endotherms can experience hyperthermia and dehydration when occupying poorly insulated nest boxes during extreme heat. In this study, we compared cavity microclimates inside different artificial hollows during extremely hot summer weather, and showed that chainsaw hollows carved into live trees provide a much more stable and buffered microclimate than do log hollows and nest boxes. We recommend that managers consider incorporating chainsaw hollows into wildlife conservation programs in regions that experience extremely hot weather events. Photograph by Stephen Griffiths. [ABSTRACT FROM AUTHOR]

Both artificial and natural regeneration of oaks strongly depend on the quantity and quality of the acorn crop, which show high year-to-year variation. The volume of the acorn crop is influenced by many factors including biotic and abiotic effects. The quality (i.e., germination ability, nutrient reserves) of acorns can be decreased by carpophagous insect and fungal pathogen damage or by inadequate weather conditions. Defoliating insects (caterpillars, sawfly larva, etc.) can significantly decrease the acorn crop as well. The most important predators of the defoliators are insectivorous birds during their nesting period. However, in the oak forests of the northern Hungarian mountains, there is a shortage of natural nesting holes. The main aim of our study was to artificially increase the number of the available nesting holes by nest boxes and to maximize the number of breeding insectivorous birds and register the direct (Lepidoptera densities) and indirect (acorn crop quantity and quality) effects of their presence. We found only slight effects on Lepidoptera densities, so we failed to demonstrate a direct effect in the relatively low time frame of our study. But, we could show the indirect positive effect of increased predation on the health state of the acorn crop, resulting in higher seedling densities, which may improve the natural regeneration potential of sessile oak. This result supports the outstanding importance of natural nesting holes in broadleaved forests.

Nest boxes and nest tubes are widely used to survey and monitor hazel dormice (Muscardinus avellanarius). A two-year study was conducted in order to compare the performance of the two devices. In one year hazel dormice clearly preferred nest tubes over nest boxes but preferred nest boxes over nest tubes in the other year. The preference for one or other device was mainly influenced by competition for nest boxes with Apodemus mice, which preferred nest boxes over nest tubes during one year when they were abundant. This has to be considered when comparing performance of methods. [ABSTRACT FROM AUTHOR]

Thermal cameras are being used increasingly in the bird-ringing community and preliminary reports suggest they have a wide range of relevant applications. However, there has been little quantitative assessment of these methods. In this study we tested the use of a thermal imager to assess the occupancy of enclosed nests, using nest-box populations of small passerines. Based on a thermal image of each nest box, observers were able to predict nest-box occupancy with a combined success rate of 85.9%. The observers were able to identify when nest boxes contained a heat source relating to an active nest but unable to differentiate between warm clutches and live broods. The age of the brood significantly influenced the predictions, reflecting the limited ability of young broods to maintain their body temperatures independently. There were no significant effects from potential confounding variables relating to solar exposure, nest-box design or ambient temperature, although these may have accounted for a small number of incorrect predictions. Overall, it was found that thermal imagers provide an effective, non-invasive and efficient method for monitoring nest-box occupancy, with inferences about suitability for other types of enclosed nest. [ABSTRACT FROM AUTHOR]

Abstract Background The feeding behavior of bloodsucking insects determines the transmission, distribution, host spectrum and evolution of blood parasites in the wild. Conventional wisdom suggests that some vector groups (e.g. black flies, family Simuliidae) are consistently exophagous daytime biters. We aimed to understand more about the exceptions to this pattern by combining targeted trapping and molecular identification of parasites in vectors. Methods In this study, we collected black flies in nest boxes used by European rollers Coracias garrulus in southeastern Spain. We molecularly analyzed 434 individual insects, identifying the black fly species caught in the nest boxes, their potential vertebrate blood meals, and the haemosporidian parasite lineages that they carried. Results Only one black fly species, Simulium rubzovianum, appeared to enter the nest boxes of rollers. Among the trapped specimens, 15% contained vertebrate DNA, which always belonged to rollers, even though only half of those specimens were visibly engorged. Furthermore, 15% of all black flies contained Leucocytozoon lineages, indicating previous feeding on avian hosts but probably not on infected adult rollers. The known vertebrate hosts of the recorded Leucocytozoon lineages suggested that large and/or abundant birds are their hosts. Particularly represented were cavity-nesting species breeding in the vicinity, such as pigeons, corvids and owls. Open-nesting species such as thrushes and birds of prey were also represented. Conclusions Our data strongly suggest that S. rubzovianum bites uninfected roller nestlings and infected individuals of other species, potentially incubating adults, inside nest boxes and natural cavities. This simuliid does not appear to have a strong preference for specific host clades. Contrary to the general pattern for the group, and possibly enhanced by the harsh environmental conditions in the study area, this black fly appeared to intensively use and may even have a preference for confined spaces such as cavities for feeding and resting. Preferences of vectors for atypical microhabitat niches where hosts are less mobile may enable social and within-family transmission and parasite speciation in the long term. At the same time, a lack of host preference in concentrated multispecies communities can lead to host switches. Both processes may be underappreciated driving forces in the evolution of avian blood parasites. Graphical abstract

Determining the ecosystem function of high-order predators is critical for evaluation of food web interactions. Insectivorous birds are abundant predators in many ecosystems yet because they forage upon small taxa, it remains largely unknown whether birds are providing ecosystem services in the form of pest control or disservices by preying upon predaceous arthropod species. We extracted DNA from noninvasive fecal samples of adult and nestling Western Bluebirds (Sialia mexicana) in California vineyards. Using universal arthropod-specific primers, we sequenced prey items via massively parallel sequencing on the Illumina MiSeq platform. Bluebirds consumed a broad diet comprising 66 unique arthropod species from 6 orders and 28 families. Aedes sp. (mosquitoes: Culicidae), a previously unknown prey, was the most common item recovered, occurring in 49.5% of the fecal samples. Ectoparasitic bird blowfly (Protocalliphora) DNA was found in 7% of adult and 11% of nestling samples, presenting clear evidence of active feeding by the avian hosts on adult or larval ectoparasites. Herbivorous insects, primarily from the orders Hemiptera and Lepidoptera, represented over half (56%) of the prey items in bluebird diets. Intraguild predation (consumption of predator or parasitoid arthropods) represented only 3% of adult and nestling dietary items. Diets of adults were significantly different from nestlings as were diets from birds sampled in different vineyard blocks. Sex, date, number of young, and individual bird (based on resampled individuals) were all insignificant factors that did not explain diet variability. Nestling age was a significant factor in explaining a small amount of the variability in dietary components. In addition, our analysis of subsampling larger fecal samples and processing them independently revealed highly dissimilar results in all 10 trials and we recommend avoiding this common methodology. Molecular scatology offers powerfully informative techniques that can reveal the ecosystem function and services provided by abundant yet cryptic avian foragers.

Determining the ecosystem function of high-order predators is critical for evaluation of food web interactions. Insectivorous birds are abundant predators in many ecosystems yet because they forage upon small taxa, it remains largely unknown whether birds are providing ecosystem services in the form of pest control or disservices by preying upon predaceous arthropod species. We extracted DNA from noninvasive fecal samples of adult and nestling Western Bluebirds (Sialia mexicana) in California vineyards. Using universal arthropod-specific primers, we sequenced prey items via massively parallel sequencing on the Illumina MiSeq platform. Bluebirds consumed a broad diet comprising 66 unique arthropod species from 6 orders and 28 families. Aedes sp. (mosquitoes: Culicidae), a previously unknown prey, was the most common item recovered, occurring in 49.5% of the fecal samples. Ectoparasitic bird blowfly (Protocalliphora) DNA was found in 7% of adult and 11% of nestling samples, presenting clear evidence of active feeding by the avian hosts on adult or larval ectoparasites. Herbivorous insects, primarily from the orders Hemiptera and Lepidoptera, represented over half (56%) of the prey items in bluebird diets. Intraguild predation (consumption of predator or parasitoid arthropods) represented only 3% of adult and nestling dietary items. Diets of adults were significantly different from nestlings as were diets from birds sampled in different vineyard blocks. Sex, date, number of young, and individual bird (based on resampled individuals) were all insignificant factors that did not explain diet variability. Nestling age was a significant factor in explaining a small amount of the variability in dietary components. In addition, our analysis of subsampling larger fecal samples and processing them independently revealed highly dissimilar results in all 10 trials and we recommend avoiding this common methodology. Molecular scatology offers powerfully informative techniques that can reveal the ecosystem function and services provided by abundant yet cryptic avian foragers.

Abstract COVID‐19 created a host of challenges for science education; in our case, the pandemic halted our in‐person elementary school outreach project on bird biology. This project was designed as a year‐long program to teach fifth‐grade students in Ithaca, New York, USA, about bird ecology and biodiversity using in‐person presentations, games, activities, and outdoor demonstrations. As a central part of this effort, we set up nest boxes on school property and planned to monitor them with students during bird breeding in the spring. Here, we describe our experiences transitioning this program online: we live streamed nest boxes to the students’ virtual classroom and used them as a focal point for virtual lessons on bird breeding and nestling development. In an era of social distancing and isolation, we propose that nest box live streaming and virtual lessons can support communities by providing access to the outdoors and unconventional science learning opportunities for all students. Instituting similar programs at local schools has the potential to increase equitable learning opportunities for students across geographic locations and with varying degrees of physical access to the outdoors and nature.

The decline of critical habitat structures, such as large old trees, is a global environmental challenge. The cavities that occur in these trees provide shelter and nesting sites for many species but can take centuries to develop. Artificial cavities, including nest boxes and carved logs, offer an increasingly important conservation response. However, current methods of designing, manufacturing and deploying such habitats have constraints that limit innovation, feasibility and effectiveness. In response, this article aims to provide new and broadly useable methods that can improve the design of habitat structures for cavity‐dependent animals.To address the shortcomings of existing methods, we develop an approach that uses computer‐aided design techniques of generative and parametric modelling to produce structures that satisfy stakeholder needs, computer‐aided manufacturing techniques of 3D printing and augmented‐reality assembly to build functional prototypes, and computer‐assisted techniques of laser scanning and data‐driven design to support installation, monitoring and iterative improvement of designs. We demonstrate this approach through a case‐study project that designs and instals habitat structures for the powerful owl Ninox strenua, a cavity‐dependent and threatened bird.Through a comparison with existing methods, our pilot study shows that computer‐aided design and manufacturing can provide novel and useful approaches to develop artificial habitat‐structures. Computer‐aided design finds geometries that approximate the complex characteristics of natural tree cavities and automatically produces new versions to suit diverse sites or species. Computer‐aided manufacturing integrates materials that match the performance of naturally occurring habitat structures and facilitates the assembly of complex geometries by non‐experts. Computer‐assisted techniques produce precisely fitting and easy‐to‐instal designs, which support gradual improvement through ongoing prototyping and evaluation.These capabilities highlight how advanced design techniques can improve aspects of artificial habitat‐structures through geometric innovation, novel construction techniques and iterative exploration. Significantly, computational approaches can result in designs that can perform well, are easy to construct and instal and are applicable in many situations. Our reusable workflow can aid in the tasks of practical conservation and support ecological research by effectively negotiating the needs of both humans and target species. [ABSTRACT FROM AUTHOR]

Abstract Artificial devices are increasingly used in conservation measures to mitigate the disappearance of natural habitats. However, few studies have demonstrated their benefits for the target species, and they may pose a risk of creating ecological traps. This occurs when lower individual fitness is found in artificial habitats that are more attractive than their natural equivalents. In this study, we tested the ecological trap hypothesis on a dense population of European rollers Coracias garrulus breeding in both natural cavities and nest boxes. Our initial prediction was that the more stressful microclimatic conditions of nest boxes would lead to reduced fitness of European rollers, thus creating an ecological trap. The results showed that nest boxes were preferred over natural cavities. Despite significantly more extreme microclimatic conditions in nest boxes, we found similar breeding parameters between artificial and natural nest types. Our results also suggest that European rollers selected the nest boxes which best buffered the temperature, thus avoiding potential ecological traps. Overall our results led to the conclusion that nest boxes do not create ecological traps for European rollers in this study area. However, other species may be more sensitive to microclimatic variations or less able to avoid the least favorable nest boxes. These findings could help to inform the placement of nest boxes in order to reduce extreme temperatures and variation in humidity rates. Future studies could compare nest types for other fitness parameters, such as juvenile body condition or survival. We also recommend the ecological trap hypothesis as a useful framework to evaluate the outcomes of artificial devices used for conservation.

Barn owls produce large numbers of young, will nest in close proximity, are easily attracted to nest boxes, and occasionally form dense colonies. Their diet consists largely of various species of rodent pests. These characteristics suggest barn owls could contribute to pest control in agriculture. Studies have been conducted in Israel and Malaysia, but little quantitative research has documented their effectiveness. This study measured the effect of a population of barn owls on a rodent population in a 40-ha vineyard near Sacramento, California. In 2011, 11 of 20 boxes were occupied by breeding pairs, fledging 40 young. In 2012, 18 of 24 owl boxes were occupied, fledging 66 young; and in 2013, three of 24 boxes were occupied, fledging nine young. Nocturnal observations revealed the owls hunted the study area heavily. Monthly pocket gopher surveys using the mound-count method indicated that gophers declined on the vineyard with barn owl boxes relative to a control vineyard without barn owl boxes. Pellet analysis showed diet was composed mainly of Botta’s pocket gophers (70.4%) and California voles (26.2%). An infrared camera recorded 316 deliveries to a nest with three chicks (105.3 per chick) over the first eight weeks. Using these figures, and adding conservative estimates of adult consumption over the 165-day breeding season, and adult and fledgling consumption prior to dispersal, the total number of prey taken over the three breeding seasons was estimated to be 30,020 rodents. Cost comparison analysis showed an average cost of $8.11 per pocket gopher trapped versus $ 0.34 per rodent taken by barn owls.

While many raptor species consume rodent pests, the behaviors and habits of barn owls make them particularly suitable candidates for consideration as a viable pest control strategy. As a cavity-nesting species, barn owls will readily nest in man-made structures including nest boxes. Barn owls are also less territorial than many other raptor species and will tolerate other pairs nesting nearby if prey is abundant. Barn owls preferentially consume rodents including voles (Microtus spp.) and pocket gophers (Thomomys spp.) in habitats where they occur, but will also switch to more abundant prey so they may be able to sustain populations even if preferred prey numbers fall. These life-history traits allow for people to inflate barn owl populations in target areas, and this has been a factor in the widespread popularity of encouraging barn owls to nest in agricultural areas to provide natural pest control of small nocturnal vertebrate pests. However, the ability of barn owls to control rodent pests has only been formally tested in Malaysian rice and palm oil agriculture, and whether barn owls are capable of controlling rodent pests to economically acceptable levels in areas such as California is as yet unknown. We extracted and combined data from field studies of barn owl nesting behavior and diet in California vineyards to predict that annually, a pair of nesting barn owls and their progeny will consume 97.85 kg of prey. We predicted that an average barn owl nest in a California vineyard will therefore consume 843 pocket gophers, 578 voles, and 1,540 other prey items, most of which are mice. At these values, a barn owl population density of one nest/10 ha may be able to offset the annual productivity of an average population of pocket gophers, but even the highest barn owl densities of one nest/2 ha would be unable to control pocket gopher populations at maximum densities and reproductive rates. While valuable for making initial predictions of the ability of owls to control small rodent pests, our prediction methods are crude, and accurately assessing the capability of barn owls to control rodent pests will require more field data and more sophisticated modeling techniques.