Winter GPS tagging reveals home ranges during the breeding season for a boreal-nesting migrant songbird, the Golden-crowned Sparrow.

Determining space use for species is fundamental to understanding their ecology, and tracking animals can reveal insights into their spatial ecology on home ranges and territories. Recent technological advances have led to GPS-tracking devices light enough for birds as small as ~30 g, creating novel opportunities to remotely monitor fine-scale movements and space use for these smaller species. We tested whether miniaturized GPS tags can allow us to understand space use of migratory birds away from their capture sites and sought to understand both pre-breeding space use as well as territory and habitat use on the breeding grounds. We used GPS tags to characterize home ranges on the breeding grounds for a migratory songbird with limited available breeding information, the Golden-crowned Sparrow (Zonotrichia atricapilla). Using GPS points from 23 individuals across 26 tags (three birds tagged twice), we found home ranges in Alaska and British Columbia were on average 44.1 ha (95% kernel density estimate). In addition, estimates of territory sizes based on field observations (mean 2.1 ha, 95% minimum convex polygon [MCP]) were three times smaller than 95% MCPs created using GPS tags (mean 6.5 ha). Home ranges included a variety of land cover classes, with shrubland particularly dominant (64-100% of home range cover for all but one bird). Three birds tracked twice returned to the same breeding area each year, supporting high breeding site fidelity for this species. We found reverse spring migration for five birds that flew up to 154 km past breeding destinations before returning. GPS-tracking technology allowed for critical ecological insights into this migratory species that breeds in very remote locations.

Selection on the joint actions of pairs leads to divergent adaptation and coadaptation of care-giving parents during pre-hatching care.

The joint actions of animals in partnerships or social groups evolve under both natural selection from the wider environment and social selection imposed by other members of the pair or group. We used experimental evolution to investigate how jointly expressed actions evolve upon exposure to a new environmental challenge. Our work focused on the evolution of carrion nest preparation by pairs of burying beetles Nicrophorus vespilloides, a joint activity undertaken by the pair but typically led by the male. In previous work, we found that carrion nest preparation evolved to be faster in experimental populations without post-hatching care (No Care: NC lines) than with post-hatching care (Full Care: FC lines). Here, we investigate how this joint activity evolved. After 15 generations of experimental evolution, we created heterotypic pairs (NC females with FC males and NC males with FC females) and compared their carrion nest making with homotypic NC and FC pairs. We found that pairs with NC males prepared the nest more rapidly than pairs with FC males, regardless of the female's line of origin. We discuss how social coadaptations within pairs or groups could act as a post-mating barrier to gene flow.

Bird nesting boxes as a specific artificial microenvironment increasing biodiversity of mites from the suborder Uropodina (Acari: Mesostigmata): a case study of Bory Tucholskie National Park.

Bory Tucholskie National Park, founded in 1996, is one of the most recently established national parks in Poland, and therefore, has not been thoroughly examined yet. The authors of the current study present results of their research concerning communities of mites from the suborder Uropodina (Acari: Mesostigmata), inhabiting bird nesting boxes within the area of Bory Tucholskie National Park. The mite community comprises two nidicolous species, i.e. Leiodinychus orbicularis (C.L. Koch, 1839) and Chiropturopoda nidiphila (Wisniewski and Hirschmann 1993). The former is a species characteristic of various types of nests, as well as nesting boxes, where it is usually the eudominant species. The latter is an extremely rare and scarce species of Uropodina, known thus far from woodpeckers' hollows. The population of L. orbicularis in the analysed communities in the realm of Bory Tucholskie National Park has been estimated to be over 6,000 specimens, and in the case of Ch. nidiphila - over 400 specimens.

Innovative monitoring scheme adapted to remote, scattered nesting aggregation reveals a major loggerhead turtle rookery in New Caledonia, South Pacific.

The loggerhead turtle Caretta caretta is a large marine turtle with a cosmopolitan repartition in warm and temperate waters of the planet. The South Pacific subpopulation is classified as 'Critically Endangered' on the IUCN Red List, based on the estimated demographic decline. This precarious situation engages an urgent need to monitor nesting populations in order to highlight conservation priorities and to ensure their efficiency over time. New Caledonia encompasses a large number of micro and distant nesting sites, localized on coral islets widely distributed across its large lagoon. Adequately surveying nesting activities on those hard-to-reach beaches can prove to be challenging. As a result, important knowledge gaps prevail in those high-potential nesting habitats. For the first time, an innovative monitoring scheme was conducted to assess the intensity of nesting activities, considered as a proxy of the population size, on an exhaustive set of islets located in the 'Grand Lagon Sud' area. These data were analyzed using a set of statistical methods specially designed to produce phenology and nesting activity estimates using Bayesian methods. This analysis revealed that this rookery hosts a large nesting colony, with a mean annual estimate of 437 nests (95% Credible Interval = 328-582). These numbers exceed that of the previous estimated annual number of loggerhead turtle nests in New Caledonia, highlighting the exceptional nature of this area. Considering the fact that similar high-potential aggregations have been identified in other parts of New Caledonia, but failed to be comprehensively assessed to this day, we recommend carrying out this replicable monitoring scheme to other locations. It could allow a significant re-evaluation of the New Caledonian nesting population importance and, ultimately, of its prevailing responsibility for the protection of this patrimonial yet endangered species.

Are man-made hives valid thermal surrogates for natural honey bee nests (Apismellifera)?

Honey bees preferentially occupy thick walled tall narrow tree cavities and attach their combs directly to the nest wall, leaving periodic gaps. However, academic research and beekeeping are conducted in squat, thin walled man made hives, with a continuous gap between the combs and the walls and roof. Utilising a computational fluid dynamics (CFD) model of thermoregulating bees in complete nests in trees and thin walled man made hives, with the average size of tree comb gaps determined from honey bee occupied synthetic tree nests, this research compared the metabolic energy impacts of comb gaps and vertical movement of the thermoregulated brood area. This shows their heat transfer regimes are disparate, including: bee space above combs increases heat loss by up to ∼70%; hives, compared to tree nests, require at least 150% the density of honey bees to arrest convection across the brood area. Tree cavities have a larger vertical freedom, a greater thermal resistance and can make dense clustering redundant. With the thermal environment being critical to honey bees, the magnitude and scope of these differences suggest that some hive based behavioural research needs extra validation to be considered non-anthropogenic, and some bee keeping practices are sub-optimal.

Contrasting nidification behaviors facilitate diversification and colonization of the Music frogs under a changing paleoclimate.

In order to cope with the complexity and variability of the terrestrial environment, amphibians have developed a wide range of reproductive and parental behaviors. Nest building occurs in some anuran species as parental care. Species of the Music frog genus Nidirana are known for their unique courtship behavior and mud nesting in several congeners. However, the evolution of these frogs and their nidification behavior has yet to be studied. With phylogenomic and phylogeographic analyses based on a wide sampling of the genus, we find that Nidirana originated from central-southwestern China and the nidification behavior initially evolved at ca 19.3 Ma but subsequently lost in several descendants. Further population genomic analyses suggest that the nidification species have an older diversification and colonization history, while N. adenopleura complex congeners that do not exhibit nidification behavior have experienced a recent rapid radiation. The presence and loss of the nidification behavior in the Music frogs may be associated with paleoclimatic factors such as temperature and precipitation. This study highlights the nidification behavior as a key evolutionary innovation that has contributed to the diversification of an amphibian group under past climate changes.

Coevolution with hosts underpins speciation in brood-parasitic cuckoos.

Coevolution between interacting species is thought to increase biodiversity, but evidence linking microevolutionary processes to macroevolutionary patterns is scarce. We leveraged two decades of behavioral research coupled with historical DNA analysis to reveal that coevolution with hosts underpins speciation in brood-parasitic bronze-cuckoos. At a macroevolutionary scale, we show that highly virulent brood-parasitic taxa have higher speciation rates and are more likely to speciate in sympatry than less-virulent and nonparasitic relatives. We reveal the microevolutionary process underlying speciation: Hosts reject cuckoo nestlings, which selects for mimetic cuckoo nestling morphology. Where cuckoos exploit multiple hosts, selection for mimicry drives genetic and phenotypic divergence corresponding to host preference, even in sympatry. Our work elucidates perhaps the most common, but poorly characterized, evolutionary process driving biological diversification.

A successional shift enhances stability in ant symbiont communities.

Throughout succession, communities undergo structural shifts, which can alter the relative abundances of species and how they interact. It is frequently asserted that these alterations beget stability, i.e. that succession selects for communities better able to resist perturbations. Yet, whether and how alterations of network structure affect stability during succession in complex communities is rarely studied in natural ecosystems. Here, we explore how network attributes influence stability of different successional stages of a natural network: symbiotic arthropod communities forming food webs inside red wood ant nests. We determined the abundance of 16 functional groups within the symbiont community across 51 host nests in the beginning and end stages of succession. Nest age was the main driver of the compositional shifts: symbiont communities in old nests contained more even species abundance distributions and a greater proportion of specialists. Based on the abundance data, we reconstructed interaction matrices and food webs of the symbiont community for each nest. We showed that the enhanced community evenness in old nests leads to an augmented food web stability in all but the largest symbiont communities. Overall, this study demonstrates that succession begets stability in a natural ecological network by making the community more even.

Nest excavators' learning walks in the Australian desert ant Melophorus bagoti.

The Australian red honey ant, Melophorus bagoti, stands out as the most thermophilic ant in Australia, engaging in all outdoor activities during the hottest periods of the day during summer months. This species of desert ants often navigates by means of path integration and learning landmark cues around the nest. In our study, we observed the outdoor activities of M. bagoti workers engaged in nest excavation, the maintenance of the nest structure, primarily by taking excess sand out of the nest. Before undertaking nest excavation, the ants conducted a single exploratory walk. Following their initial learning expedition, these ants then engaged in nest excavation activities. Consistent with previous findings on pre-foraging learning walks, after just one learning walk, the desert ants in our study demonstrated the ability to return home from locations 2 m away from the nest, although not from locations 4 m away. These findings indicate that even for activities like dumping excavated sand within a range of 5-10 cm outside the nest, these ants learn and utilize the visual landmark panorama around the nest.

Developmental stage-dependent effects of perceived predation risk on nestling tree swallows (Tachycineta bicolor).

The risk of predation directly affects the physiology, behavior, and fitness of wild birds. Strong social connections with conspecifics could help individuals recover from a stressful experience such as a predation event; however, competitive interactions also have the potential to exacerbate stress. Few studies have investigated the interaction between environmental stressors and the social landscape in wild bird populations. In 2 years of field studies, we experimentally simulated predation attempts on breeding female tree swallows (Tachicyneta bicolor). At the same time, we manipulated female breast plumage color, a key social signal. Simulated predation events on tree swallows early in the nestling period reduced young nestlings' mass by approximately 20% and shortened telomere lengths. Ultimately, only 31% of nestlings in the predation group fledged compared with 70% of control nestlings. However, the effects of experimental manipulations were timing dependent: the following year when we swapped the order of the experimental manipulations and simulated predation during incubation, there were no significant effects of predation on nestling condition or fledging success. Contrary to our expectations, manipulation of the social environment did not affect the response of tree swallows to simulated predation. However, manipulating female plumage during the nestling period did reduce nestling skeletal size and mass, although the effects depended on original plumage brightness. Our data demonstrate that transient stressors on female birds can have carry-over effects on their nestlings if they occur during critical periods in the breeding season.

Do birds select the plastics debris used for nest construction? A case study in a Mediterranean agricultural landscape.

Plastic pollution is becoming a global problem due to its ubiquitous occurrence and the impacts detected for many species. However, the research about plastics in nests of terrestrial bird species has remained relatively overlooked in comparison to those devoted to marine ecosystems. Here we study the occurrence and patterns of use of anthropogenic material in nests of two passerine birds, the Eurasian magpie (Pica pica) and the European serin (Serinus serinus), breeding in an orange tree cultivation in Mediterranean Spain. Our results show that both species use extensively plastic debris as nest material; almost 71% of the European serin nests and 96% of nests of Eurasian magpies contained plastic debris. Furthermore, by analyzing the plastic debris availability in the agricultural landscape surveyed we confirmed a selection pattern in the two species. Thus, both species preferably select plastic filaments over other plastic debris. The Eurasian magpie does not select plastic based on size or color but the European serin avoid black plastics prefer smaller fragments in comparison to the average size available. Moreover, we suggest the apparent similarity of plastic filaments with the natural materials typically used by these species, as well as how they use the plastic in their nests could influence their selection behavior. More studies focused on terrestrial birds inhabiting human modified habitats could offer a deeper approach to how plastic debris interacts with wildlife in different ways.

Androgen and glucocorticoid profiles throughout extended uniparental paternal care in the eastern hellbender salamander (Cryptobranchus a. alleganiensis).

The behavioral endocrinology associated with reproduction and uniparental male care has been studied in teleosts, but little is known about hormonal correlates of uniparental male care in other ectotherms. To address this gap, we are the first to document the seasonal steroid endocrinology of uniparental male hellbender salamanders during the transition from pre-breeding to nest initiation, and through the subsequent eight months of paternal care. In doing so, we investigated the correlates of nest fate and clutch size, exploring hellbenders' alignment with several endocrinological patterns observed in uniparental male fish. Understanding the endocrinology of hellbender paternal care is also vital from a conservation perspective because high rates of nest failure were recently identified as a factor causing population declines in this imperiled species. We corroborated previous findings demonstrating testosterone and dihydrotestosterone (DHT) to be the primary androgens in hellbender reproduction, and that cortisol circulates as the most abundant glucocorticoid. However, we were unable to identify a prolactin or a "prolactin-like" peptide in circulation prior to or during parental care. We observed âˆ¼ 80 % declines in both primary androgens during the transition from pre-breeding to nest initiation, and again as paternal care progressed past its first month. In the days immediately following nest initiation, testosterone and DHT trended higher in successful individuals, but did not differ with males' clutch size. We did not observe meaningful seasonality in baseline glucocorticoids associated with breeding or nesting. In contrast, stress-induced glucocorticoids were highest at pre-breeding and through the first two months of care, before declining during the latter-most periods of care as larvae approach emergence from the nest. Neither baseline nor stress-induced glucocorticoids varied significantly with either nest fate or clutch size. Both stress-induced cortisol and corticosterone were positively correlated with total length, a proxy for age in adult hellbenders. This is consistent with age-related patterns in some vertebrates, but the first such pattern observed in a wild amphibian population. Generally, we found that nesting hellbenders adhere to some but not all of the endocrinological patterns observed in uniparental male teleosts prior to and during parental care.

Accumulation rate and sources of plastic marine litter at nesting grounds of green turtles on the North Island of Qilianyu, Xisha Islands, South China Sea.

In this study, the accumulation rate of plastic litter was investigated by sampling quadrats placed on the North Island of Qilianyu, and the composition was analyzed and identified to determine its source. The results showed that the annual average accumulation rate of plastic litter on North Island was 0.64 ± 0.32 pieces·m-2·month-1, with a mass accumulation rate of 11.30 ± 7.73 g·m-2·month-1. The accumulation rate of plastic litter was mainly influenced by wind speed and direction, with higher accumulation rates occurring during the southwest monsoon season and tropical cyclones. ATR-FTIR analysis indicated that polyethylene (44 %) and polypropylene (41 %) were the most abundant types of polymers. This study reveals the current status of plastic litter pollution in green turtle nesting grounds on North Island in Qilianyu, which can be used as a reference for management strategies that mitigate plastic litter pollution.

Collective behaviour: Stingless bees are self-organised nest builders.

A new study compiles compelling evidence that stingless bees construct their brood combs in a self-organised manner in which local modification of a structure stimulates further modifications, a process known as stigmergy.

Will a changing climate affect hatching success in cavity-nesting birds: A case study with Eastern Bluebirds (Sialia sialis)?

A significant body of evidence indicates that climate change is influencing many aspects of avian ecology. Yet, how climate change is affecting, and is expected to influence some aspects of the breeding ecology of cavity-nesting birds remains uncertain. To explore the potential linkage between timing of first clutch, and the influence of ambient temperature on hatching success, we used Eastern Bluebird (Sialia sialis) nest records over a nine-year period from Alabama, USA. We investigated changes to annual clutch initiation dates, as well as variability in hatching success associated with ambient air temperatures during the incubation period. Using a simple linear model, we observed earlier annual egg laying dates over the nine years of this study with a difference of 24 days between earliest egg-laying date of the season. Daily temperature minima increased 2 °C across the nine-year time frame of this study. These data also indicate that Eastern Bluebird hatching success was the highest when mean ambient air temperature during incubation was between 19 °C and 24 °C (78%, as opposed to 69% and 68% above and below this temperature range, respectively). Our findings of increasing maxima, earlier maxima each year, and the lower minima of temperatures within our study area could expand the breadth of temperatures experienced by nesting Eastern Bluebirds possibly exposing them to temperatures outside of what promotes nesting success. These findings with a cavity-nesting bird highlight an optimal range of ambient temperatures associated with highest hatching success, conditions likely to be affected by climate change.

Why do avian responses to change in Arctic green-up vary?

Global climate change has altered the timing of seasonal events (i.e., phenology) for a diverse range of biota. Within and among species, however, the degree to which alterations in phenology match climate variability differ substantially. To better understand factors driving these differences, we evaluated variation in timing of nesting of eight Arctic-breeding shorebird species at 18 sites over a 23-year period. We used the Normalized Difference Vegetation Index as a proxy to determine the start of spring (SOS) growing season and quantified relationships between SOS and nest initiation dates as a measure of phenological responsiveness. Among species, we tested four life history traits (migration distance, seasonal timing of breeding, female body mass, expected female reproductive effort) as species-level predictors of responsiveness. For one species (Semipalmated Sandpiper), we also evaluated whether responsiveness varied across sites. Although no species in our study completely tracked annual variation in SOS, phenological responses were strongest for Western Sandpipers, Pectoral Sandpipers, and Red Phalaropes. Migration distance was the strongest additional predictor of responsiveness, with longer-distance migrant species generally tracking variation in SOS more closely than species that migrate shorter distances. Semipalmated Sandpipers are a widely distributed species, but adjustments in timing of nesting relative to variability in SOS did not vary across sites, suggesting that different breeding populations of this species were equally responsive to climate cues despite differing migration strategies. Our results unexpectedly show that long-distance migrants are more sensitive to local environmental conditions, which may help them to adapt to ongoing changes in climate.

Eviction-driven infanticide and sexually selected adoption and infanticide in a neotropical parrot.

Infanticide and adoption have been attributed to sexual selection, where an individual later reproduces with the parent whose offspring it killed or adopted. While sexually selected infanticide is well known, evidence for sexually selected adoption is anecdotal. We report on both behaviors at 346 nests over 27 y in green-rumped parrotlets (Forpus passerinus) in Venezuela. Parrotlets are monogamous with long-term pair bonds, exhibit a strongly male-biased adult sex ratio, and nest in cavities that are in short supply, creating intense competition for nest sites and mates. Infanticide attacks occurred at 256 nests in two distinct contexts: 1) Attacks were primarily committed by nonbreeding pairs (69%) attempting to evict parents from the cavity. Infanticide attacks per nest were positively correlated with population size and evicting pairs never adopted abandoned offspring. Competition for limited nest sites was a primary cause of eviction-driven infanticide, and 2) attacks occurred less frequently at nests where one mate died (31%), was perpetrated primarily by stepparents of both sexes, and was independent of population size. Thus, within a single species and mating system, infanticide occurred in multiple contexts due to multiple drivers. Nevertheless, 48% of stepparents of both sexes adopted offspring, and another 23% of stepfathers exhibited both infanticide and long-term care. Stepfathers were often young males who subsequently nested with widows, reaching earlier ages of first breeding than competitors and demonstrating sexually selected adoption. Adoption and infanticide conferred similar fitness benefits to stepfathers and appeared to be equivalent strategies driven by limited breeding opportunities, male-biased sex ratios, and long-term monogamy.

Prolactin is associated with proximity to incubating partner rather than parental care in black-headed gulls.

The peptide hormone prolactin plays an important role in the expression of parental care behaviours across bird and mammal taxa. While a great deal is known about how plasma prolactin concentrations vary across the reproductive cycle, the few studies that investigate how prolactin relates to individual-level variation in parental care have reported mixed results. We argue that, since parental care is also affected by social interactions and environmental constraints, prolactin may better reflect behaviours that are indirectly related to parenting than the absolute level of care that is eventually expressed. In this study, we tested for associations between plasma prolactin and the expression of both parental care and proximity to the partner in incubating black-headed gulls, Chroicocephalus ridibundus. Baseline prolactin levels increased with calendar date but were unrelated to incubation behaviours. However, parents who showed a weaker decrease in prolactin to an acute stressor spent more time in close proximity to their incubating partner while not on the nest themselves, suggesting that individual variation in stress-induced prolactin changes reflect differences in parents' tendency to be closely associated with their partner and the joint nesting attempt. Baseline and stress-induced levels of the stress hormone corticosterone were unrelated to both prolactin levels and parental behaviours, suggesting that this hormone is not a strong moderator of parental care in black-headed gulls. One potential explanation for the link between prolactin dynamics and partner proximity is that prolactin reflects parental motivation to provide parental care or retain contact with the breeding partner, but further work is needed to directly test this hypothesis.

Comparison of the blood biochemical values of foraging and nesting Olive Ridley turtles (Lepidochelys olivacea) from Sinaloa, Mexico.

Our study aimed to establish reference values for nesting females and compare them with those previously reported to understand olive ridley turtles' health status and contribute to long-term health assessment and monitoring in foraging and nesting areas from the state of Sinaloa, Mexico. In August and September 2018, morphometric data and biochemical profiles were collected from 33 nesting olive ridley turtles from Ceuta Beach Sanctuary (CBS) and 14 foraging female turtles captured at the foraging site, Navachiste Marine Area (NMA). Nesting turtles sampled had greater CCL (65.86 ± 1.70 cm) than those from the foraging area (61.54 ± 1.22) (p < 0.05). Regarding biochemical profiles, post-nesting turtles had higher packed cell volume (PCV), albumin, blood urea nitrogen (BUN), cholesterol, triglycerides, and calcium than turtles from the foraging area (p < 0.05). Phosphorus levels were higher in foraging turtles than in nesting turtles (p = 0.001), while the remaining parameters showed no significant differences. The present study describes for the first time the blood biochemical values of nesting turtles from the Ceuta Beach Sanctuary in southern Sinaloa, Mexico, similar to those of foraging turtles from the north of the state. The significant differences observed between the two analysis groups may be due to the energy reserves and reproductive and nesting activity of the nesting turtles, so the blood biochemistry values described in this study can be used as a standard reference blood value for the olive ridley turtle population of Sinaloa, Mexico.

Urban rooftops near sports pitches provide a safe haven for a declining shorebird.

Urbanisation has contributed to a severe decline in biodiversity worldwide. However, urban ecosystems can also play an important role in the conservation of threatened species, including ground-nesting birds such as the Eurasian Oystercatcher (Haematopus ostralegus). While the coastal populations of this shorebird have declined sharply, there is growing evidence that pairs nesting on urban flat roofs have high reproductive success. However, the reasons for rooftop nesting and the species' habitat use in urban areas remain poorly understood. In this study, we investigate the territory selection and foraging behaviour of the Eurasian Oystercatcher in the city of Münster (NW Germany). All nesting sites were located on flat roofs (N = 24), most of which were covered with gravel. Overall, reproductive success was high. This was mainly because the roofs provided protection from mammalian predators, leading to increased nest and chick survival. Moreover, breeding performance in the study area was favoured by the proximity of sports pitches. According to our observations, they provided a large amount of easily accessible prey throughout the breeding season. Overall, our study highlights that the reproductive success of the Eurasian Oystercatcher in urban environments is highly dependent on both safe nesting sites on flat roofs and the availability of suitable foraging habitats. Although our study suggests that breeding in urban areas can be beneficial for the model organism, the species' strong territory fidelity makes it very sensitive to the rapid environmental changes occurring in cities. The value of urban ecosystems for bird conservation should therefore be better integrated into urban planning and management.