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Understanding distribution patterns and multitrophic interactions is critical for managing bat- and bird-mediated ecosystem services such as the suppression of pest and non-pest arthropods. Despite the ecological and economic importance of bats and birds in tropical forests, agroforestry systems, and agricultural systems mixed with natural forest, a systematic review of their impact is still missing. A growing number of bird and bat exclosure experiments has improved our knowledge allowing new conclusions regarding their roles in food webs and associated ecosystem services. Here, we review the distribution patterns of insectivorous birds and bats, their local and landscape drivers, and their effects on trophic cascades in tropical ecosystems. We report that for birds but not bats community composition and relative importance of functional groups changes conspicuously from forests to habitats including both agricultural areas and forests, here termed 'forest-agri' habitats, with reduced representation of insectivores in the latter. In contrast to previous theory regarding trophic cascade strength, we find that birds and bats reduce the density and biomass of arthropods in the tropics with effect sizes similar to those in temperate and boreal communities. The relative importance of birds versus bats in regulating pest abundances varies with season, geography and management. Birds and bats may even suppress tropical arthropod outbreaks, although positive effects on plant growth are not always reported. As both bats and birds are major agents of pest suppression, a better understanding of the local and landscape factors driving the variability of their impact is needed.

In resident Amazonian mixed-species flocks, the pattern of attraction of transient species to nuclear Dusky-throated Antshrikes (Thamnomancs ardesiacus) and Long-winged Antwrens (Myrmotherula longipennis) and the pattern of heterospecific attraction between the nuclear species are undocumented. Patterns of attraction can help elucidate the nature of interspecific relationships (i.e., whether they are mutualistic, commensal, or parasitic). We played Dusky-throated Antshrike and Long-winged Antwren vocalizations to flocks and recorded how many transient species approached the playbacks, whether the antshrikes and antwrens were attracted to each other's playbacks, and how strongly they responded to the playbacks. More transient species were attracted to the antshrike vocalizations than antwren vocalizations, and more transient species were attracted to antwren than control vocalizations. Dusky-throated Antshrikes and Long-winged Antwrens approached each other's playback significantly more often than they approached control playbacks; the antwrens responded significantly more strongly to antshrike vocalizations than the antshrikes did to antwren vocalizations. Species may be more attracted to Dusky-throated Antshrikes because of their reliable alarm calling, whereas species may be attracted to antwrens because they serve as a flock indicator. Finally, Dusky-throated Antshrikes and Long-winged Antwrens likely confer benefits to each other, but those benefits may not be symmetrical. Received 7 August 2016. Accepted 3 March 2017. Key words: antbirds, interspecific interactions, mutualism, Neotropical, playback, Thamnophilidae. En bandadas mixtas que viven en Amazonia, la pauta de attracción de especies transitorios y especies centros, como los Thamnomanes ardesiacus y Myrmotherula longipennis, y la pauta de attracción entre los especies centros no son documentados. Pautas de attraccion puede elucidar el índole de las relaciones entre especies diferentes (como mutualismo, comensalismo, o parasitismo). Tocamos vocalizaciones de T. ardesiacus y M. longipennis a bandadas mixtas y recordamos el numero de especies que acercaron, si T. ardesiacus y M. longipennis se atrajeron a sus vocalizaciones, y la fuerza de atracción. Más especies transitorios se atrataron a las vocalizaciones del T. ardesiacus que el M longipennis, y más especies transitorios de atrataron a las vocalizaciones del M. longipennis que el control cientifico. T. ardesiacus y M. longipennis acercaron las vocalizaciones del otro más que ellos acercaron la vocalizacion del control; el M. longipennis respondió con mas fuerza a las vocalizaciones del T. ardesiacus que el T. ardesiacus respondió a las vocalizaciones del M. longipennis. Es possible que los especies son más atraidos al T. ardesiacus porque el T. ardesiacus hace vocalizaciones alarmas cuando hay un depredador. Al fin, el T. ardesiacus y el M. longipennis probablemente conficron beneficios al otro, pero los beneficios son asimétricos. Palabras clave: hormigueros, intcraccines interespecíficas, mutualismo, Neotropical, reproducción dc vocalizaciones, Thamnophilidae., Hundreds of species worldwide participate in mixed-species flocks, defined as [greater than or equal to]2 species moving together for [greater than or equal to]5 min without a concentrated feeding source [...]

Some fruit-eating bird species commonly consume cultivated fruit. Species-specific variation in diet preferences could result in varying use of orchards and impacts on the fruit-producing industry. However, species-specific studies of avian orchard use are lacking, particularly throughout the fruit-growing season. Our objectives were to quantify the frequency of daily bird visits to orchards and the amount of time birds spent visiting orchards each day over the fruit-ripening season. Birds are well-documented consumers of cultivated sweet cherries (Prunus avium), which are relatively high in sugar and low in proteins and lipids. American Robins (Turdus migratorius) and Cedar Waxwings (Bombycilla cedrorum) are common fruit-consumers in sweet cherry orchards. Robins often consume larger proportions of invertebrates and prefer lipid-rich fruits, while waxwings choose sugary fruits. Given these species-specific diet differences, we hypothesized waxwings would spend a greater proportion of days and more time each day in cherry orchards, compared to robins. We used radio telemetry to track the habitat use of 25 American Robins and 17 Cedar Waxwings in sweet cherry orchards of Michigan. Over their respective radio-tracking periods, waxwings visited orchards a greater percentage of days than robins (waxwings: mean = 21%, SD = 22; robins: mean = 6%, SD = 4). In addition, waxwings visited orchards for more time each day. Differences in diet preferences and nutritional physiology may translate into species-specific patterns of habitat use for birds in fruit-rich environments. Received 4 February 2015. Accepted 2 August 2015. Key words: American Robin, Cedar Waxwing, cherry, foraging, habitat use, orchard, telemetry., Animals are expected to forage where and when they can obtain sufficient accessible and nutritious foods (Hengeveld et al. 2009). Orchards offer rich patches of foraging habitat with abundant food [...]

We monitored nesting attempts of White-throated (Turdus assimilis) and Clay-colored thrushes (T. grayi) over 4 years in southern Costa Rica to compare nest success in recently abandoned coffee (Coffea spp.) plantations, pasture, and along roads. Daily mortality rates of Clay-colored Thrush nests were lower in pasture (0.054 [+ or -] 0.014) than abandoned coffee plantations (0.096 [+ or -] 0.012). Daily mortality rates of White-throated Thrush nests were not influenced by land-cover type but were lower at highly concealed nests (0.058 [+ or -] 0.005) compared to less concealed nests (0.090 [+ or - ]0.017), and at nests that were on the ground (0.0580 [+ or -] 0.005) versus in vegetation (0.076 [+ or -] 0.007). Daily mortality rates for nests of both species were very low at an active coffee plantation where nests were monitored in 1 year (0.006 [+ or -] 0.004 and 0.015 [+ or -] 0.015, for White-throated and Clay-colored thrushes, respectively). Nests at the active plantation were heavily concealed which, along with results for White-throated Thrushes in abandoned coffee, indicates concealment has a strong influence on tropical thrush nest success. Nest success appears to be heavily dependent on factors that may influence both concealment and or habitat for predators. Nest success also appears to be strongly site-specific, making it difficult to provide general statements about the conservation value of different land-cover types. Received 22 September 2010. Accepted 9 February 2011., An estimated 50% of what was once tropical forest has been cleared (Wright 2005). The agricultural land-cover types that replace tropical forest will influence future population sizes and fates of [...]

Woodpeckers are a significant source of mortality of emerald ash borer (EAB) (Agrilus planipennis Fairmaire), an Asian phloem-feeding insect first discovered in North America in 2002. However, factors that may influence woodpecker-EAB interactions have not been investigated. We collected data on woodpecker predation, EAB density and tree and site characteristics in southeastern Michigan, where EAB first became established. We tested statistical models to assess the ability of these variables to account for woodpecker predation levels. We observed foraging woodpeckers in the field to determine which species foraged on ash, and to compare the time spent foraging on ash vs. other tree species. Levels of woodpecker predation on EAB were variable, ranging from zero to 26.3 woodpecker attacks per [m.sup.2] for green ash (n = 15 sites) and from 2.3 to 37.1 attacks per [m.sup.2] for white ash (n = 7 sites). Woodpecker predation level was positively associated with the EAB density in a tree. White ash had higher predation levels than green ash, and less forested sites had higher predation levels than forested sites. However, these variables explained a relatively small amount of the variation in woodpecker predation level. Hairy, downy and red-bellied woodpeckers were observed foraging on ash trees. Woodpeckers spent significantly more time in foraging bouts on ash than on other tree species in EAB-infested areas. We suggest that managers of sites with substantial ash populations maintain conditions that are attractive to woodpeckers to encourage predation of EAB. Our analyses indicate that we need to understand much more about the foraging patterns of woodpeckers on EAB to be able to predict their impact on EAB populations., INTRODUCTION Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), threatens more than eight billion ash (Fraxinus sp.) trees in the continental U.S. EAB, native to Asia, was identified in [...]

Tropical birds may differ from temperate birds in their sensitivity to forest edges. We provide predictions about the proportions of tropical and temperate species that should avoid or exploit edges, and relationships between natural-history characters and edge responses. We conducted exploratory meta-analyses from 11 studies using 287 records of 220 neotropical and temperate species' responses to edges to address our predictions. A higher proportion of neotropical species were edge-avoiders compared with temperate species and a higher proportion of temperate species were edge-exploiters compared with neotropical species. Edge-avoiding responses were positively associated with being an insectivore for neotropical birds, and with being of small body mass and a latitudinal migrant for temperate birds. Temperate edge-exploiters were less likely to be insectivores and migrants than temperate birds that were not edge-exploiters. A greater proportion of neotropical birds than temperate birds may be at risk from forest fragmentation if edge-avoidance is a reasonable indicator of an inability to adapt to land-cover change. Future progress in our understanding of forest bird responses to edges is dependent upon greater standardization of methods and designing studies in the context of recent theoretical developments., The conversion of forest to other land-cover types leads to creation of edges (Murcia 1995). Species' responses to land-cover change and edge creation in temperate forests may not be generalizable [...]

Many studies investigating edge effects on forest-nesting birds have focused on nest success. Fewer have examined edge effects on other components of fitness. Nestling growth rates have been positively correlated with food availability, which may differ at edges compared to the forest interior. However, previous work has not examined growth as a function of distance to edge and edge type. We investigated whether edge type, distance to edge, hatching date, brood size, brood parasitism, year, and site influenced growth rates of wings, tarsi, and mass of nestling Wood Thrushes (Hylocichla mustelina) using regression tree analyses. Simultaneously, we examined edge effects on daily nest survival. We conducted our study in southwestern Michigan in 2002 and 2003. We located 175 nests and measured nestlings from 61 nests. Contrary to expectations, tarsal and mass growth rates were more rapid near edges than in the forest interior and tarsal growth rates were more rapid near gradual edge types than near abrupt edge types. Wing chord growth rates were more rapid in the forest interior than at edges. Mass and tarsal growth rates were more rapid later in the breeding season, when brood sizes were smaller. We found no effect of edge type or distance to edge on nest survival. The influence of edge on nestling growth rate but not nest survival suggests nestling growth rates may indicate edge-interior and edge type differences in habitat quality, even when high regional fragmentation levels overwhelm potential edge-interior differences in nest survival. Key words: distance to edge, edge effects, edge type, Hylocichla mustelina, nest survival, nestling growth rates, Wood Thrush. Muchos de los estudios que investigan los efectos de borde en las aves que nidifican en bosques se han enfocado en el exito de los nidos. Menos estudios han examinado los efectos de borde en otros componentes de la adecuacion biologica. Las tasas de crecimiento de los pichones han sido positivamente correlacionadas con la disponibilidad de alimentos, la cual puede diferir entre los bordes y el interior del bosque. Sin embargo, los trabajos previos no han examinado el crecimiento en funcion de la distancia al borde y del tipo de borde. Usando analisis de arboles de regresion, investigamos si el tipo de borde, la distancia al borde, la fecha de eclosion, el tamano de la nidada, el parasitismo de la nidada, el ano y el sitio influenciaron las tasas de crecimiento de las alas, el tarso y el peso de los pichones de Hylocichla mustelina. Simultaneamente, examinamos los efectos de borde en la supervivencia diaria de los nidos. Realizamos nuestro estudio en el sudoeste de Michigan en 2002 y 2003. Localizamos 175 nidos y medimos pichones provenientes de 61 nidos. Contrariamente a lo que esperabamos, las tasas de incremento del tarso y del peso fueron mayores cerca de los bordes que en el interior del bosque, y las tasas de incremento del tarso fueron mayores cerca de bordes de tipo gradual que cerca de bordes de tipo abrupto. Las tasas de incremento de la cuerda alar fueron mayores en el interior del bosque que en los bordes. Las tasas de incremento del peso y el tarso fueron mayores al final de la estacion reproductiva, cuando el tamano de la nidada fue mas pequeno. No encontramos un efecto del tipo de borde y de la distancia al borde en la supervivencia de los nidos. La influencia del borde en la tasa de crecimiento de los pichones, pero no en la supervivencia de los nidos, sugiere que la tasa de crecimiento de los pichones podria indicar diferencias en la calidad de habitat entre borde e interior y entre tipos de borde, aun cuando los altos niveles de fragmentacion regionales tengan efectos superiores a las diferencias potenciales en la supervivencia del nido entre borde e interior.

We used radiotelemetry to study behavior of White-throated Robins (Turdus assimilis) during the postfledging dependent period. The study was conducted in a mixed agricultural and forested landscape in southern Costa Rica from March through August of 2001 and 2002. A transmitter was attached to one fledgling per brood (n = 53). Each bird was located daily prior to dispersal. We compared survivorship, habitat use, and movements of fledglings from (1) nests in coffee plantations and (2) nests in cattle pastures. The probability of surviving the first three weeks out of the nest was 0.67 [+ or -] 0.07 (SE) for fledglings from nests in all habitats, 0.58 [+ or -] 0.10 for fledglings from nests in coffee, and 0.74 [+ or -] 0.26 for fledglings from nests in pasture. Fledglings from nests in pasture left their nesting habitat at younger ages than did those from nests in coffee, and most birds from both habitats moved into forest when they left their nesting habitat. Pasture was rarely used during the postfledging period, whereas coffee plantations were used extensively. Fledglings that remained in agricultural habitats (coffee or pasture) were less likely to survive until dispersal than were those that moved into forested areas. Average daily distances from the nest gradually increased until fledglings dispersed away from the natal area, always into forest, and were not different for birds from pasture or coffee. White-throated Robins can nest successfully in agricultural habitats, but use of forest positively influenced survivorship of young during the postfledging dependent period.

We document characteristics of the previously undescribed nest, nest site, and eggs of the Ochre-breasted Antpitta (Grallaricula flavirostris). We found three nests in 1999 and 2000 in the Talamanca Mountains of southern Costa Rica. The nests were cup shaped and constructed primarily of green moss with linings of thin sticks and black rhizomorphs. Mean nest height above the ground was 3.1 m. Nests were located in the forks of slim saplings in two eases and, in one case, in a larger tree at a point where several smaller branches left the trunk. We observed clutches of one and two eggs. Eggs appeared pale reddish brown with some darker spotting. The incubation period was 17-21 d and we estimate the nestling period lasts 14-16 d., Many aspects of the biology of most antpittas (Formicariidae) are not well understood because the birds are easily overlooked and relatively difficult to observe (Robbins et al. 1994), with new [...]

I recorded and analyzed vocalizations of Synallaxis albescens from three populations in Venezuela, two continental and one island, to assess the extent of geographic variation for a species of the family Furnariidae. Previous work on geographic variation in suboscines has focused on species of the Tyrannidae. I also tested the sound environment hypothesis. From nine vocalization characters I created discriminant functions that best separated the three populations. I then used classification analyses to determine how well the discriminant function models assigned individuals to their home populations. Classification analyses using discriminant functions created from first songs of recorded individuals correctly assigned individuals to their home populations 74.1% of the time and 66.7% of the time for functions created from arbitrarily chosen sixth songs. The island population was significantly more variable than either of the continental populations for the first syllable length but not for the frequency-modulated portion of the second syllable. The results demonstrate that geographic variation exists among populations although a sufficient amount of similarity prevents unequivocal classification of 1/4 to 1/3 of individuals to their home populations. The results regarding vocalization variability provide weak support for the sound-environment hypothesis., The avian order Passeriformes comprises two suborders, the oscines, suborder Passeri, and the suboscines, suborder Tyranni. The oscines developed the ability to learn vocalizations and now produce songs that are [...]

Nest usurpation and nest-niche convergence have higher prevalence in valuable nest areas, like cavities and enclosed nest areas. They are also common in areas with low structural heterogeneity of vegetation and diverse assemblages of possible competitors/associates and predators. Species that excavate or form cavities and enclosed-type nests are usually hosts of the usurpers. Cavity usurpations are common in temperate zones, while enclosed nest usurpations are common in closed habitats and tropical/subtropical zones.

From 1990 through 1993, I examined the interactions among a group of bird species in central Venezuela that use the multichambered stick nests of the Plain-fronted Thornbird (Phacellodomus rufifrons). Eleven species besides thornbirds, referred to as associates, used thornbird nests as nest sites and, in some cases, roost sites. During the 18-month study, 130 incidents of associates nesting in thornbird nests were recorded. More than 90% of thornbird territories observed for at least two breeding seasons (n = 33) had at least one associate nesting attempt. Four species accounted for over 86% of the attempts by associates: Cattle Tyrants (Machetornis rixosus), Stripe-backed Wrens (Campylorhynchus nuchalis), Saffron Finches (Sicalis flaveola), and Troupials (Icterus icterus). Sometimes thornbird and associate nesting attempts overlapped, taking place within the same nest in different chambers, or in different thornbird nests within a territory. Nine of 27 (33%) thornbird nesting attempts at the beginning of the 1991 breeding season overlapped associate attempts, and 5 of 26 (19%) overlapped in 1992. Nesting with associates involved benefits and costs for the thornbirds. In 1991, thornbird nesting attempts that overlapped Troupial nesting attempts were no more likely to succeed (33% successful, n = 6) than attempts with no associate overlap (28% successful, n = 18). Thornbird attempts that overlapped those of other species, however, were significantly more likely to succeed than attempts with no overlap (100% successful, n = 3). In 1992, patterns were similar (0% successful with Troupials, n = 2; 10% successful with no associates, n = 21; 33% successful with other associates, n = 3), although high thornbird nest mortality and small sample sizes precluded statistical analysis. Thornbird nesting attempts that overlapped two associate nesting attempts (n = 7, 1991 and 1992 combined) had a high success rate (71%). Rainfall in the month before fledging was positively associated with the number of fledglings produced in 1991, but not in 1992. Nest-guarding behavior by associates and enhanced mobbing of predators (demonstrated in predator-presentation experiments) were likely mechanisms of enhanced reproductive success when thornbirds nested with associates. Thornbirds often were treated with aggression by associates, and circumstantial evidence indicated that Troupials sometimes preyed on thornbird eggs and nestlings. Valuable nest sites may lead coexisting species to converge, rather than diverge, in their use of this resource. Received 20 February 1995, accepted 26 July 1995.