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The American crocodile (Crocodylus acutus) is the most widely distributed New World crocodile. However, the species has experienced severe declines due to overexploitation. In South Florida, loss of nesting habitat, with coastal degradation from sea level rise and urban development has prompted American crocodiles to nest in novel habitats. Crocodile Lake National Wildlife Refuge (CLNWR) serves as an important nesting site for the South Florida population of American crocodiles and more recently nesting habitat has been supplemented to manage coastal erosion. The goal of this study was to investigate the internal nest biology of American crocodile nests laid in sediment nourished sand mounds on CLNWR. We monitored internal nest temperature and volumetric water content of five live and two control sand nests in 2021 (N = 73 eggs) and 2022 (N = 84 eggs). The metabolic heat generated by incubating eggs in internal nest temperatures ranged from 0.8°C to 2.0°C warmer and more stable than ambient temperatures and reflecting a seasonal pattern. Average clutch size was 31.4 ± 7.09 eggs and incubation period ranged from 78 to 114 days until hatching. These data provide the first insight into thermal regimes of nests laid in novel/supplemented nesting habitat as is the case for a significant proportion of nests in the South Florida population of American crocodiles. Here we provide an opportunity to evaluate the importance of creating artificial nesting habitat for American crocodiles where habitat degradation from climate change threatens species survival. [ABSTRACT FROM AUTHOR]

The first breeding of osprey (Pandion haliaetus) on Jeju Island, South Korea, were observed in 2015, and ospreys bred on three sites. We found a total of three nests and observed that A site nest bred on successfully from 2017 to 2020. The number of eggs per clutch ranged from two to four, with a mean ± SD of 3.16 ± 0.75. The nesting period varied from 71 days to 79 days, with an average duration of 76.2 ± 3.18 days. The incubation period ranged from 34 days to 38 days, averaging 35.8 ± 1.72 days. Fledging dates ranged from July 4th to 13th. The nest tree species was Pinus thunbergii, and the average tree height was 16.2 ± 3.12 m. On average, the nest height from the ground was 14.8 ± 2.57 m. The average diameter at breast height of the nesting trees was 36.1 ± 2.02 cm. Of the total 19 eggs produced, the hatching rate was 91.4% ± 10.2%, fledgling rate was 68.6% ± 26.9%, and breeding success was 65.6% ± 25.1%. Little ecological information is available on osprey living in South Korea; therefore, this study makes a meaningful contribution to provide baseline ecological data from South Korea for this species.

Insect-associated microorganisms play important roles in the health and development of insects. This study aimed to investigate the similarities and differences in bacterial community structure and composition between the larval gut of Osmia excavata, nest soil, and brood provision from the nest tube. We sequenced larvae gut and their environments' microorganisms of O. excavata from four locations based on full-length 16S rRNA gene amplicons. The results showed 156, 280, and 366 bacterial OTUs from gut, brood provision, and nest soil, respectively, and three groups shared 131 bacterial OTUs. In the gut, the top two dominant bacteria were Sodalis praecaptivus (68.99%), Lactobacillus micheneri (17.95%). In the brood provision, the top two dominant bacteria were S. praecaptivus (26.66%), Acinetobacter nectaris (13.05%), and in the nest soil, the two most abundant bacteria were Gaiella occulta (4.33%), Vicinamibacter silvestris (3.88%). There were significant differences in diversity between the brood provision groups and the nest soil groups, respectively. Three of the four locations did not differ for gut microbial diversity. Bacteria similar to other solitary bees also existed in the gut of the larvae. Results indicated when the habitat environments were similar, the bacterial community diversity of the gut of O. excavata was similar, despite significant differences among brood provisions and soils, respectively. [ABSTRACT FROM AUTHOR]

The nest environment may limit the ability of nest-bound birds to hear sounds from the outside world. In vocal learning species, such as humans and songbirds, it is vital for young animals to hear the voices of conspecific animals early in life. In songbirds, nest structure varies considerably across species, and the resulting impact on sound transmission may have consequences for vocal learning in nestlings. In this study, we tested the hypothesis that the nest environment attenuates song of Savannah Sparrows (Passerculus sandwichensis), grassland songbirds that build nests on the ground under cover of dense vegetation. We recorded live Savannah Sparrows singing at variable distances from 21 nests. We recorded songs using one microphone inside the nest (the typical position of a nestling) and another placed 1 m directly above the nest (a typical position of an adult). We found a substantial reduction in signal-to-noise ratio, where songs recorded inside the nest were an average of 11 dB lower than songs recorded directly above the nest. We estimate that the attenuation imposed by the nest reduced the maximum acoustic environment from 117.7 m (for recordings above the nest), to 78.6 m (for recordings within the nest), which is analogous to listening from a position 39.1 m farther away from the singer. Previous research estimated that song transmits up to 100 m in this species, so any adult male within 100 m of a young bird was previously considered a potential vocal tutor. By reducing the nestling acoustic environment from 100 m to 78.6 m, the number of male tutors available to nestlings is reduced by an average of 27%. Given the growing evidence that song learning begins very early in life, future research on vocal development should account for how the structural properties of the natal environment affect the songs that nestlings hear.

Insect-associated microorganisms play important roles in the health and development of insects. This study aimed to investigate the similarities and differences in bacterial community structure and composition between the larval gut of Osmia excavata, nest soil, and brood provision from the nest tube. We sequenced larvae gut and their environments’ microorganisms of O. excavata from four locations based on full-length 16S rRNA gene amplicons. The results showed 156, 280, and 366 bacterial OTUs from gut, brood provision, and nest soil, respectively, and three groups shared 131 bacterial OTUs. In the gut, the top two dominant bacteria were Sodalis praecaptivus (68.99%), Lactobacillus micheneri (17.95%). In the brood provision, the top two dominant bacteria were S. praecaptivus (26.66%), Acinetobacter nectaris (13.05%), and in the nest soil, the two most abundant bacteria were Gaiella occulta (4.33%), Vicinamibacter silvestris (3.88%). There were significant differences in diversity between the brood provision groups and the nest soil groups, respectively. Three of the four locations did not differ for gut microbial diversity. Bacteria similar to other solitary bees also existed in the gut of the larvae. Results indicated when the habitat environments were similar, the bacterial community diversity of the gut of O. excavata was similar, despite significant differences among brood provisions and soils, respectively.

The debate about behavioral thermoregulation inside reptile eggs centers on the frequency (and hence, biological significance) of the phenomenon, not about its validity. Both sides of the debate agree that large eggs in shallow nests laid in sun‐exposed soil will experience clines in mean temperature and (especially) diel thermal variance; that embryos in the middle phase of development have the ability to reposition themselves, and room to do so; and that small changes in developmental temperatures can influence offspring fitness. Equally, all protagonists agree that thermal clines will be too low in some other kinds of nests, and that embryonic repositioning is impossible very early and very late in development. Based on an array of other fitness‐enhancing behaviors exhibited by tetrapod embryos, and general principles for recognizing adaptation, we conclude that behavioral thermoregulation inside the egg likely is adaptive in some but not all reptile species. We identify productive directions for empirical research to resolve points of contention. Reptile embryos affect their temperatures by moving around in the egg. Contrary to recent criticisms, embryos during mid‐development are capable of moving and have adequate space in which to do so. [ABSTRACT FROM AUTHOR]

Low-oxygen conditions (hypoxia; <21% O2) are considered unfavorable for growth; yet, embryos of many vertebrate taxa develop successfully in hypoxic subterranean environments. Although enhanced tolerance to hypoxia has been demonstrated in adult reptiles, such as in the painted turtle ( Chrysemys picta), its effects on sensitive embryo life stages warrant attention. We tested the hypothesis that short-term hypoxia negatively affects growth during day 40 of development in C. picta, when O2 demands are highest in embryos. A brief, but severe, hypoxic event (5% O2 for 0.5 h) moderately affected embryo growth, causing a 13% reduction in mass (relative to a normoxic control). The same condition had no effect during day 27; instead, a nearly anoxic event (1% O2 for 72 h) caused a 5% mass reduction. All embryos survived the egg incubation period. Our study supports the assumption that reptilian embryos are resilient to intermittently low O2 in subterranean nests. Further work is needed to ascertain responses to suboptimal O2 levels while undergoing dynamic changes in developmental physiology. [ABSTRACT FROM AUTHOR]

The nest environment may limit the ability of nest-bound birds to hear sounds from the outside world. In vocal learning species, such as humans and songbirds, it is vital for young animals to hear the voices of conspecific animals early in life. In songbirds, nest structure varies considerably across species, and the resulting impact on sound transmission may have consequences for vocal learning in nestlings. In this study, we tested the hypothesis that the nest environment attenuates song of Savannah Sparrows (Passerculus sandwichensis), grassland songbirds that build nests on the ground under cover of dense vegetation. We recorded live Savannah Sparrows singing at variable distances from 21 nests. We recorded songs using one microphone inside the nest (the typical position of a nestling) and another placed 1 m directly above the nest (a typical position of an adult). We found a substantial reduction in signal-to-noise ratio, where songs recorded inside the nest were an average of 11 dB lower than songs recorded directly above the nest. We estimate that the attenuation imposed by the nest reduced the maximum acoustic environment from 117.7 m (for recordings above the nest), to 78.6 m (for recordings within the nest), which is analogous to listening from a position 39.1 m farther away from the singer. Previous research estimated that song transmits up to 100 m in this species, so any adult male within 100 m of a young bird was previously considered a potential vocal tutor. By reducing the nestling acoustic environment from 100 m to 78.6 m, the number of male tutors available to nestlings is reduced by an average of 27%. Given the growing evidence that song learning begins very early in life, future research on vocal development should account for how the structural properties of the natal environment affect the songs that nestlings hear. [ABSTRACT FROM AUTHOR]

Social insects are well known for their high level of cooperation. Workers of the primitively eusocial bumblebee Bombus terrestris are able to produce male offspring in the presence of a queen. Nonetheless, they only compete for reproduction, in the so-called competition phase, when the workforce is large enough to support the rearing of reproductives. So far, little is known about the proximate mechanisms underlying the shift between altruism and selfish behaviour in bumblebee workers. In this study, we have examined the influence of chemical cues from the nest wax on the onset of worker reproduction. Chemical analyses of wax extracts have revealed that the patterns and amounts of cuticular lipids change considerably during colony development. These changes in wax scent mirror worker abundance and the presence of fertile workers. In bioassays with queen-right worker groups, wax affects the dominance behaviour and ovarian development of workers. When exposed to wax from a colony in competition phase, workers start to compete for reproduction. We suggest that wax scent enables workers to time their reproduction by providing essential information concerning the social condition of the colony.

Nest traps are one of the most common methods to study Osmia bees. To elucidate the optimal environmental conditions of nesting sites, we investigated the effects of location, direction, altitude, and sites of nest traps on the rate of trap-nesting Osmia spp. During the collection period, the average rate of trap-nesting Osmia spp. collected within 90 days after the installation of traps was 17.0 ± 20.0%. This percentage was 2.7-fold higher than that of trap-nesting bees in 30 days after the installation of traps. The Jeongseon location exhibited the highest rates of trap-nesting Osmia spp. collected in 30 and 90 days, representing 11.1 ± 17.6% and 23.2 ± 22.5%, respectively. The direction of the nest traps did not affect the rate of trap-nesting Osmia spp. The altitude ranges of the traps were 0–199 m, 200–399 m, 400–599 m, 600–799 m and over 800 m. Interestingly, the altitude range of 600–799 m showed the highest rate of trap-nesting bees, which was 40.4 ± 3.9%. Higher altitudes seemed to correspond to higher rates of trap-nesting bees. With regards to the sites where the nests were placed, the rate of trap-nesting bees in a mud wall of an old house was 45.1 ± 25.2%, which was 3-fold higher than that of a nest in an apple orchard. The flowering plants collected at different locations during the trap-nesting activity of Osmia bees belonged to 18 families and 34 species. In conclusion, the rates of trap nests colonized by Osmia spp. were affected by altitude, site, and plant diversity. [ABSTRACT FROM AUTHOR]

Variable temperatures within a nest cause asynchronous development within clutches of freshwater turtle embryos, yet synchronous hatching occurs and is thought to be an important survival strategy for hatchlings. Metabolic compensation and circadian rhythms in heart rates of embryonic turtles indicate the potential of communication between embryos in a nest. Heart rates were used to identify metabolic circadian rhythms in clutches of an Australian freshwater turtle ( Chelodina longicollis ) and determine whether embryos metabolically compensate and hatch synchronously when incubated in asynchronous environments. The effects of a group environment during incubation on egg development and incubation period were also investigated during the final 3 weeks of development. Chelodina longicollis hatch synchronously and metabolically compensate so that less advanced embryos catch up to more advanced clutch-mates. Heart rates of embryos remained stable from week 4–7 in asynchronous (M = 89 bpm) and synchronous (M = 92 bpm) groups and declined in the final 2 weeks of incubation (M = 72 and 77 bpm). Circadian rhythms were present throughout development and diel heart rates of embryos in asynchronous groups showed less deviation from the mean (M = − 0.5 bpm) than synchronous groups (M = − 4 bpm). Eggs incubated in groups had a significantly shorter incubation period than eggs incubated individually. Phenotypic traits including size, performance, and growth of all hatchlings were not affected. Egg position within a turtle nest is important for coordinating development throughout incubation and facilitating synchronous hatching. [ABSTRACT FROM AUTHOR]

Many temperate animals spend half their lives in a non-active, overwintering state, and multiple adaptations have evolved to enable winter survival. One notable vertebrate model is Chrysemys picta, whose hatchlings display dichotomous overwintering strategies: some hatchlings spend their first winter aquatically after nest emergence in the autumn, whereas others overwinter terrestrially within their natal nest with subsequent emergence in the spring. The occurrence of these strategies varies among populations and temporally within populations; however, factors that determine the strategy employed by a nest in nature are unknown. We examined potential factors that influence intra-population variation in the overwintering strategy of C. picta hatchlings over two winters in Algonquin Park, Ontario. We found that environmental factors may be a trigger for the hatchling overwintering strategy: autumn-emerging nests were sloped towards the water and were surrounded by a relatively higher percentage of bare ground compared with spring-emerging nests. Autumn-emerging hatchlings were also relatively smaller. Overwintering strategy was not associated with clutch oviposition sequence, or mammalian or avian predation attempts. Instead, autumn emergence from the nest was associated with the direct mortality threat of predation by sarcophagid fly larvae. Body condition and righting response, measured as proxies of hatchling fitness, did not differ between overwintering strategies. Costs and benefits of overwintering aquatically versus terrestrially in hatchling C. picta are largely unknown, and have the potential to affect population dynamics. Understanding winter survival has great implications for turtle ecology, thus we emphasize areas for future research on dichotomous overwintering strategies in temperate hatchling turtles. [ABSTRACT FROM AUTHOR]

Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (GH2o) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell GH2o and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in GH2o has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between GH2o and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher GH2o than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher GH2o than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's γ) was intermediate in magnitude, suggesting that differences observed in the GH2o are dependent upon a combination of shared ancestry and speciesspecific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher GH2o to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher GH2o to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours. [ABSTRACT FROM AUTHOR]

Tropical termites are physiologically adapted to a narrow range of climatic conditions, and as a result may be particularly impacted by global climate change. Because of their key roles as decomposers and ecosystem engineers, any climatic impact on termites could have serious ramifications for tropical ecosystems. The ability of termites to mediate their nest environment could allow them to cope with these changes., The temperature and RH in nests of the tropical termite Nasutitermes acajutlae were compared with ambient conditions on the island of St John, U.S. Virgin Islands, over a 5-year period using data loggers inserted into nest cartons., Nest conditions were found to be significantly warmer, more humid, and less variable than ambient conditions with respect to both temperature and RH., A comparison of dead nests, live non-reproductive nests, and live reproductive nests revealed that temperature mediation appears to be primarily the result of the presence of termites, with reproductive nests producing the highest temperatures, while high RH is maintained by the insulating effects of the nest material., Environmental variability across the years of this study had a significant influence on nest temperature and RH, suggesting that if tropical conditions become warmer and drier as predicted, N. acajutlae may have difficulty adapting over the long term. [ABSTRACT FROM AUTHOR]

Social insects are well known for their high level of cooperation. Workers of the primitively eusocial bumblebee Bombus terrestris are able to produce male offspring in the presence of a queen. Nonetheless, they only compete for reproduction, in the so-called competition phase, when the workforce is large enough to support the rearing of reproductives. So far, little is known about the proximate mechanisms underlying the shift between altruism and selfish behaviour in bumblebee workers. In this study, we have examined the influence of chemical cues from the nest wax on the onset of worker reproduction. Chemical analyses of wax extracts have revealed that the patterns and amounts of cuticular lipids change considerably during colony development. These changes in wax scent mirror worker abundance and the presence of fertile workers. In bioassays with queen-right worker groups, wax affects the dominance behaviour and ovarian development of workers. When exposed to wax from a colony in competition phase, workers start to compete for reproduction. We suggest that wax scent enables workers to time their reproduction by providing essential information concerning the social condition of the colony.