Individual Nests Research Articles

Nest remains are insufficient to identify predators of waterfowl nests

Context Nest predation is a leading cause of nest failure for most ground-nesting birds. Methods that allow for accurate classification of fate and identification of predators are important for understanding productivity and conservation strategies. Past studies have used a visual inspection of nest remains to determine nest fate and predict predator identity. Most formal assessments of these methods have addressed small-bodied birds nesting in trees or shrubs, and have revealed that use of evidence at nests can be relatively accurate for determining nest fate but may lead to incorrect conclusions regarding predator identity. However, few have tested the latter hypothesis for larger ground-nesting birds with precocial young. Aim We aimed to evaluate a classification system developed for determining nest fate and identifying predators of waterfowl nests, at both the scale of individual nests and across the study area. Methods From 2016 to 2020, we located 989 blue-winged teal (Spatula discors), mallard (Anas platyrhynchos) and gadwall (Mareca strepera) nests in central North Dakota. We placed cameras at a subset of 249 nests and recorded evidence of nest remains at depredated nests. Key results The most common predators were American badgers (Taxidea taxus), followed by striped skunks (Mephitis mephitis), raccoons (Procyon lotor) and red foxes (Vulpes vulpes). Using evidence of nest remains, we determined nest fates with high accuracy (98.0%). However, evidence of nest remains was only sufficient for identifying predators at 50% of nests, and the classification system was correct only 69.7% of the time. The predicted proportion of predators across the study area differed between the classification system and our video evidence as well. Conclusions The accuracy of predator identifications based upon the classification system that we evaluated was not supported at any scale. Implications Our results suggest that evidence of nest remains can be used to determine nest fate for large-bodied precocial, ground-nesting birds, but accurate identification of nest predators will require alternative methods such as nest cameras.

Habitat selection by a predator of rodent pests is resilient to wildfire in a vineyard agroecosystem.

Conservation of uncultivated habitats can increase the potential for ecosystem services in agroecosystems, but these lands are also susceptible to wildfires in the arid western United States. In Napa Valley, California, abundant rodent pests and an interest in integrated pest management have led wine producers to use nest boxes to attract Barn Owls (Tyto furcata) to winegrape vineyards. The viability of this practice as a method to control rodent pests depends heavily on the amount of hunting effort that Barn Owls expend in vineyards, which is known to be influenced by the amount of uncultivated land cover types surrounding the nest box. Wildfires burned nearly 60,000 ha of mainly urban and uncultivated lands surrounding Napa Valley in 2017, altering Barn Owl habitats. We compared GPS tracking data from 32 Barn Owls nesting in 24 individual nest boxes before and after the fires to analyze their hunting habitat selection. Owls with burned areas available to them after the fires had home ranges that shifted toward the fires, but selection was not strongly associated with burned areas. Though there was some spatial use of burned areas, selection of land cover types was similar for birds before and after the fires and in burned and unburned areas. The strongest selection was for areas closest to the nest box, and most recorded locations were in grassland, though selection indicated that owls used land cover types in proportion to their availability. Overall, habitat selection was resilient to changes caused by wildfires. These results are important for farmers who use nest boxes as a means of rodent control, which may be affected after dramatic disturbance events, especially as wildfires increase in the western United States.

Individual Scent-Marks of Nest Entrances in the Solitary Bee, Osmia cornuta (Hymenoptera: Apoidea).

Simple SummaryOsmia cornuta is a solitary mason bee that uses natural pre-existing cavities, such as beetle worm traces or hollow plant stalks, for nest construction. Such nesting opportunities can often be found pretty close to each other, leading to dense aggregations of many nesting bees. Therefore, it is crucial for females returning from collecting flights to localize their own nests’ entrance among many other similar-looking holes. Individual scent marks of entrances were suspected to be used by bees as olfactory cues additional to visual orientation. We used paper sleeves introduced in the nest entrances to identify the substances involved in marking and compared the composition with secretions of the Dufour’s gland and substances present on the body surface. Although the nest marks were found to be ample diverse, tags did not perfectly render individual odor bouquets nor did bees possess private chemicals. Instead, females used an individual mixture of body-derived substances enriched by external components to produce distinguishable tags that alter over time. The smell of the own nest has to be learned continuously by the resident female as a template to identify her own nest at the next arrival from a provision flight.The ability to recognize the own nest is a basic skill in nest constructing solitary bees. Osmia cornuta females use a dual mechanism of visual orientation to approach a nest and olfactory verification of the tube when entering it. Occupied tubular cavities were steadily marked by the resident female. Nest marking substances originate from Dufour’s gland and cuticle, enriched by external volatiles. Scent tags were dominated by alkanes and alkenes in a species-specific mixture enriched by small amounts of fatty acid esters, alcohols, and aldehydes. The individual nest tags are sufficiently variable but do not match perfectly with the nesting female. Furthermore, tags are not consistent over time, although females continue in marking. Besides the correct position of the entrance in space, bees have to learn also the bouquet of the used cavity and update their internal template at each visit to recognize their own nest by its actual smell. Due to the dominance of the species-specific hydrocarbon pattern, nest marks may function not only as an occupied sign but may also provide information on the species affiliation and constitution of the nest owner.

Individual Nest Site Preferences Do Not Explain Upslope Population Shifts of a Secondary Cavity-Nesting Species.

Simple SummaryEnvironmental changes such as climate change have affected wildlife species behavior and geographic ranges globally. We analyzed nesting data of western bluebirds to determine whether the link between geographic range shifts of a western bluebird population in New Mexico, USA is due to individual adaptations or changes occurring at a larger scale. We looked at location data of marked and recaptured nestlings and adults that nested within our study area. We found that individual choices have no impact on the geographic range shift being observed in this population, suggesting that population-level processes, such as emigration and immigration, may be the main cause of these shifts.Geographic ranges of plants and animals are shifting due to environmental change. While some species are shifting towards the poles and upslope in elevation, the processes leading to these patterns are not well known. We analyzed 22 years of western bluebird (Sialia mexicana) data from a large nest box network in northern New Mexico at elevations between 1860 m and 2750 m. This population has shifted to higher elevations over time, but whether this is due to changes in nesting behavior and preference for higher elevation within the population or driven by immigration is unclear. We banded adults and nestlings from nest boxes and examined nesting location and elevation for individual birds captured two or more times. Most recaptured birds nested at the same nest boxes in subsequent years, and the number of birds that moved upslope did not significantly differ from the number that moved downslope. Fledglings moved greater distances and elevations than adults, but these movements were not upslope specific. Female fledglings showed greater changes in elevation and distance compared to male fledglings, but again, movements were not consistently upslope. The upslope shift in this population may be due to birds immigrating into the population and not from changes in individual nesting behavior.

Breeding performance of the White-throated Dipper (Cinclus cinclus) under different temperature conditions

Many bird species breeding under optimal temperature conditions show higher reproductive success. However, less information can be found about how the reproductive output differs within one population and one breeding season. To find inter and intra-seasonal differences in several aspects of breeding ecology and breeding output we monitored 223 breedings of the White-throated Dippers within the three river basins of northern Slovakia (Central Europe) in 2010–2018. We registered the beginning of egg laying, clutch size, nest success and the proportion of second clutches. There were significant differences in egg-laying commencement between breeding seasons. The mean February and March temperature significantly influenced the first egg day (20 February–18 March), median laying date (8 March–6 April), the interval between the first and the last first egg in all clutches in one breeding season (37–50 days) and the proportion of second clutches (0.77%–0.95%). However, the differences were found not only between different seasons. The egg-laying initiation of individual nests within each season was considerable affected by the altitude and the proportion of second clutches of particular nests was significantly influenced by their timing of egg laying.

Nesting and hatching behaviour of Olive Ridley Turtles Lepidochelys olivacea (Eschscholtz, 1829) (Reptilia: Cryptodira: Cheloniidae) on Dr. Abdul Kalam Island, Odisha, India

This paper reports the nesting, impact of lunar phase and rainfall on mass nesting, hatching, and hatchling behaviour of L. olivacea in Dr. Abdul Kalam Island, Bhadrak District, Odisha. The study site is a well-known rookery for this species. A study of 15 mass nesting events between 2003 and 2020 using Rayleigh’s test indicated that the onset of mass nesting was not uniform across a lunar month, but was most intense towards the beginning of the fourth quarter moon (mean lunar day = 22.44). Also, rainfall and mass-nesting data from 2015 to 2020 revealed that ≥3.2 mm rainfall in February delayed mass nesting from the second fortnight of February to the end of the first fortnight of March. Sporadic nesting continued after hatching commenced in May, and continued until the end of May 2020, with an average of three turtles nesting each day. At night, a cohort of hatchlings from individual nests emerged synchronously. Before emergence they remained a little beneath the sand surface in airy-shallow pits. During hatchling emergence these pits fill with sand, leaving depressions described as “emergence craters” in recent literature on L. olivacea. To study hatchling emergence 30 such craters were examined in May 2020, and the numbers of emerged hatchlings per cohort varied from 28 to 182. Of 30 craters examined, 28 were circular and two were elliptical, with diameters varying between 10 and 26 cm. Pearson’s correlation coefficient between the numbers of emerged hatchlings and crater diameter was 0.38. Hatchlings took 17 min 22 sec (SD= ±5min 30 sec) on average to reach the sea from a mean distance of 34.6m.

Interannual climate variation influences nest initiation date and nest productivity of the Red-cockaded Woodpecker at the northwestern edge of its range

AbstractClimate change, including directional shifts in weather averages and extremes and increased interannual weather variation, is influencing demography and distributions for many bird species. The Ouachita Mountains ecoregion in southeast Oklahoma and west-central Arkansas contains 2 populations of the Red-cockaded Woodpecker (Dryobates borealis, RCW), a federally endangered, cooperatively breeding species. Since this region is at the RCW’s northwestern range periphery, ecological thresholds likely are limiting for the species. Therefore, populations in this region may be more sensitive to climate change-associated weather variation and unpredictability. We used 26 years of nesting data (1991–2016) from the 2 RCW populations to determine if interannual weather variation has affected nesting phenology and productivity. For each population, we used daily temperature and precipitation data for 3 periods (30 and 60 days before nesting; 40 days overlapping the nesting period) to determine how weather influences median nesting date and average clutch size and numbers of fledglings. In a separate analysis, we used shorter time windows with individual nests as replicates to determine how discrete weather events (e.g., minimum and maximum temperatures and intense precipitation events) affect nest success and partial brood loss. For both Oklahoma and Arkansas populations, warmer early spring temperatures generally advanced nesting and increased clutch size and fledgling number. However, the effects of average precipitation varied depending on the amount and duration of precipitation in different time periods. At the nest level, most variables reflecting discrete temperature and precipitation events were unrelated to nest success and brood loss, suggesting that factors other than weather (e.g., habitat quality and predation) more strongly influenced the nesting output of individual RCW broods. Our results indicate RCWs are responding to interannual weather variation in complex and variable ways. However, warming trends may generally be having positive effects on the species at the northwestern edge of its range.

Nest microclimate and limits to egg viability explain avian life-history variation across latitudinal gradients.

Variation in life-history strategies is central to our understanding of population dynamics and how organisms adapt to their environments. Yet we lack consensus regarding the ecological processes that drive variation in traits related to reproduction and survival. For example, we still do not understand the cause of two widespread inter- and intraspecific patterns: (1) the ubiquitous positive association between avian clutch size and latitude; and (2) variation in the extent of asynchronous hatching of eggs within a single clutch. Well-known hypotheses to explain each pattern have largely focused on biotic processes related to food availability and predation risk. However, local adaptation to maintain egg viability could explain both patterns with a single abiotic mechanism. The egg viability hypothesis was initially proposed to explain the cause of asynchronous hatching and suggests that asynchronous hatching results from early incubation onset in response to unfavorable nest microclimatic conditions, which otherwise reduce egg viability. However, allocation of resources to early incubation, prior to clutch completion, may energetically constrain clutch size and help explain the positive association between clutch size and latitude. We measured intraspecific variation in five functionally linked life-history traits of burrowing owls at five study sites spanning a 1,400-km latitudinal transect in western North America: clutch size, the timing of incubation onset, the degree of hatching asynchrony, the probability of hatching failure, and nestling survival. We found that most traits varied clinally with latitude, but all the traits were more strongly associated with individual nest microclimates than with latitude, and all varied with nest microclimate in the directions predicted by the egg viability hypothesis. Furthermore, incubation began earlier, hatching asynchrony increased, and clutch size declined across the breeding season. These results suggest that nest microclimate drives an important life-history trade-off and that thermal gradients are often sufficient to account for observed biogeographic and seasonal patterns in life-history strategies. Furthermore, our results reveal a potentially important indirect mechanism by which reproductive success and recruitment could be affected by climate change.

Colony characteristics influence nest survival of Caribbean Roseate Terns

AbstractDetermining how site characteristics influence reproductive success can help guide conservation planning for declining wildlife populations. For colonially breeding seabirds, nest survival and predation risk can be influenced by both colony and nest site characteristics such as colony size, nest density, and nest location. We evaluated the reproductive success of a declining population of Roseate Terns (Sterna dougallii) in the United States and British Virgin Islands to identify primary causes of nest failure and investigate the influence of colony and nest site covariates on nest survival. In addition, we measured the influence of colony characteristics on chick provisioning to determine if resource competition in larger colonies affected foraging rates. Monitoring was conducted in 2017–2018 via motion-triggered cameras, which enable 24-hr monitoring with minimal nest disturbance. Nest survival was defined by both hatch success and early chick success, defined as a chick surviving from hatching through the fourth post-hatch day. We monitored 118 nests in 6 colonies over the 2 breeding seasons. We found that predation was the primary cause of nest failure. Both hatch and nest success increased with colony size, and neither nest survival nor predation probability was influenced by individual nest site characteristics. Provisioning rates were comparable among colony sites and did not vary with colony size. Our results suggest that directing management efforts toward enhancing colony size, rather than focusing on nest site characteristics, can be beneficial for tropical seabird conservation.

Invasive ants reduce nesting success of an endangered Hawaiian yellow-faced bee, Hylaeus anthracinus

Hawaii has a single group of native bees belonging to the genus Hylaeus (Hymenoptera: Colletidae) and known collectively as Hawaiian yellow-faced bees. The majority of the 63 species have experienced significant declines in range and population. In 2016, seven species received federal protection under the Endangered Species Act of 1973. Competitors and predators, such as invasive bees, wasps and ants, are thought to be important drivers of range reductions and population declines, especially at lower elevations where more non-native species occur. We evaluated the effects of invasive ants on nesting Hylaeus anthracinus using artificial nest blocks that allowed us to track nest construction and development. The blocks were placed in pairs at 22 points encompassing three sites on the north and east sides of Oahu. One block in each pair was treated with a sticky barrier to prevent access by ants, while the other block remained untreated. From December 2015 to December 2016, we monitored 961 individual nests in the blocks. Seventy percent of nests in control blocks were invaded by ants. Nests in treated blocks were more likely to produce at least one adult than nests in untreated blocks (38% vs. 14%, respectively). In untreated blocks, ants were the most common cause of nest mortality followed by lack of development, displacement (primarily by the competitor Pachodynerus nasidens) and presumed pathogens. The invasive ant, Ochetellus glaber was the only observed nest predator, although the big-headed ant, Pheidole megacephala was also present. Hylaeus anthracinus inhabits coastal strand habitat which occurs in a narrow band just above the high tide line. Nests at one site were destroyed due to a high wave event, highlighting this species’ vulnerability to sea level rise. Additionally, no adult bees or nests were observed at the points where yellow crazy ants, Anoplolepis gracilipes were established. An increased understanding of the factors limiting Hawaii’s yellow-faced bees will provide information for future conservation efforts that may include landscape-scale ant control, habitat restoration and translocations.

Differences in use of bryophyte species in tit nests between two contrasting habitats: an urban park and a forest

A considerable number of avian species tend to use bryophytes as nest construction material, but the selectivity of birds in their bryophyte use in nest construction in relation to the availability of particular mosses in individual territories remains largely unexplored. We studied the bryophyte composition of nests in two passerine species: the Blue Tit Cyanistes caeruleus and the Great Tit Parus major in two floristically and structurally contrasting study areas (a mature deciduous forest and an urban parkland). We also studied territories within a radius of 10 m from each occupied nest box, listing all bryophyte species and checking to what extent the moss composition of the nest reflected what was available in the surrounding of the nest box. Both tit species appeared to be selective. The tits used a total of 31 bryophyte species in their nests (27 found in Blue Tits and 19 in Great Tits), whereas 25 additional bryophyte species were found around (10 m radius) the studied nests, but not in the nests. The number of bryophyte species found in individual nests varied in the urban parkland between 1 and 6 and in the forest between 1 and 11. The average number of bryophytes in the nest ranged from 2.31 in Great Tit from the urban parkland to 3.52 in Blue Tit in the urban parkland. Only a few species were used in a higher proportion than 5% of the volume within a single nest and, considering only these most abundant bryophyte species, the mean number ranged from 1.28 in Great Tits in the forest to 1.57 in Blue Tits in the urban parkland. Our study also showed that, in general, the bryophyte species composition of the nests seems to be affected by the site (the urban park vs the forest) rather than the parid species (Blue Tit vs Great Tit).

Гніздування окремих представників перетинчастокрилих (Hymenoptera, Aculeata) у стаціонарних штучних гніздових конструкціях на території ботанічного саду НУБіП України

Green areas of the city (remnants of the natural landscape, parks, squares, etc.) are a refuge for most diverse organisms, include insects too. Such places provide them with fodder and nesting resources under certain conditions. However, as a result of the sanitary measures of a care, the simplification of the vegetation, etc., these places become unattractive to biota, which leads to the reduction of the most common urbotolerant species of insects. In order to preserve and maintain populations of some insect species, artificial nesting structures are installed in the most attractive and safe areas. We studied the trap nest (a set of reed tubes) for insects, which was located on the territory of the botanical garden NUBIP of Ukraine. As a result of the study of 50 separate nests, the species composition of individual groups of the wild bees and wasps inhabiting such nests was described. Measurements of individual nests (diameter and length of the reed tube) were made and it was found that the population of the insects, in particular Osmia bicornis (Linnaeus, 1758) (Apoidea, Megachilidae) and the wasps of the genus Trypoxylon Latreille, 1896 (Crabronidae) is almost 95 % with dominance of O. bicornis (78 %). It was determined that Osmia are not preferred to the nest with tubes of larger diameter or length, but the diameter and length of the reed tubes are positively correlated with the number of the bees larvae in the nest (the correlation coefficients are 0.44 and 0.48, p = 0.05, respectively). The wasps (Trypoxylon sp.) was preferred to the tubes with a diameter of mainly 0.5-0.7 cm (r = 0.56, p = 0.05). In addition, the composition of kleptoparasites, which lead to the death of the bee larvae, was studied. Thus, 20 % of Osmia nests were infected with flies Cacoxenus indagator Loew, 1858 (Diptera, Drosophilidae), and 10 % of the nests contained pollen mite Chaetodactylus osmiae (Dufour, 1839) (Arachnida, Sarcoptiformes).

Parentage Analysis in the White-Tailed Eagle Haliaeetus albicilla: Are Moulted Feathers from Nest Sites a Reliable Source of Parental DNA?

Existing parentage analyses of large raptors have mostly used naturally shed feathers as a source of DNA. There is evidence that eagle nests are sometimes visited by conspecifics. Are these visitors involved in extra pair-paternity? More than 400 feather samples of nestlings and full-grown White-tailed Eagles were obtained in May at 13 nest sites in the Czech Republic, mainly during the years 2010–2016. The samples were genotyped at six microsatellite loci to determine the identity and number of individuals occurring at each nest site and to test genetic monogamy. In the end, 110 unique genotypes of possible parents were identified from moulted feathers found below nests and were used in a parentage analysis together with 86 offspring genotypes. Interestingly, more than two adult genotypes were sampled from shed feathers in one-third of 64 checks of 11 nests, but nest success was not affected by the number of genotypes. No case of extra-pair paternity was recorded. The results showed that feathers of individuals other than the parent pair can be found below nests of White-tailed Eagles during a single breeding season, and the identity of parents at individual nests can change even during seven years of study, which is inconsistent with the expected longevity, lifelong monogamy and presumed territoriality of White-tailed Eagles. We cannot recommend DNA sampling of nesting pairs on the basis of feathers found below eyries, because the most likely parent was recorded in the appropriate year only in 58% of cases with this method.

Body size of ectotherms constrains thermal requirements for reproductive activity in seasonal environments

Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary with body size at both inter- and intra-specific levels because large individuals have greater thermal inertia, retaining preferred body temperatures for a longer period of time. We use decades of data on thousands of individual nests from Algonquin Park, Ontario, Canada, to explore how body size is associated with nesting behaviour in Painted Turtles (Chrysemys picta (Schneider, 1783); small bodied) and Snapping Turtles (Chelydra serpentina (Linnaeus, 1758); large bodied). We found that (i) between species, Painted Turtles nest earlier in the evening and at higher mean temperatures than Snapping Turtles, and (ii) within species, relatively large individuals of both species nest at cooler temperatures and that relatively larger Painted Turtles nest later in the evening compared with smaller Painted Turtles. Our data support the thermal inertia hypothesis and may help explain why turtles in general exhibit geographic clines in body size: northern environments experience more daily variation in temperature, and larger size may evolve, in part, for retention of preferred body temperature during terrestrial forays.

Assessing impacts of angling for nesting Florida bass Micropterus floridanus on individual nest success

Assessing impacts of angling for nesting Florida bass <i>Micropterus floridanus</i> on individual nest success

Solitary breeding barn swallows pay a higher nest defense cost

Successful reproduction depends on the ability of parents to defend from nest predators. Breeding birds often put their life at risk to defend their offspring from predators. Communal nest defense has been proposed as an individual benefit of group living. We tested this by experimentally exposing a short-lived avian species to a potential risk of predation. We presented decoys of both a diurnal and a nocturnal predator to barn swallows Hirundo rustica breeding solitarily and in large colonies in South-western Spain. We found clear benefits of group living compared to solitary pairs in relation to investment in individual nest defense and the capacity to deter a challenging predator. Although we did not find differences in the time needed to detect the predator, we found that the number of individuals recruited to participate in nest defense was greater for colonial breeding pairs, leading to fewer attacks per individual in comparison to solitary breeding pairs. We also found that barn swallows defended their nests more vigorously against a nocturnal predator than against a diurnal predator. Therefore, barn swallows living in groups obtained clear benefits in communal nest defense by reducing the risk, energy and time dedicated to nest defense. Colonial breeding is thus a more effective strategy for decreasing nest predation rates.

Spatial and temporal variation in nest temperatures forecasts sex ratio skews in a crocodilian with environmental sex determination.

Species displaying temperature-dependent sex determination (TSD) are especially vulnerable to the effects of a rapidly changing global climate due to their profound sensitivity to thermal cues during development. Predicting the consequences of climate change for these species, including skewed offspring sex ratios, depends on understanding how climatic factors interface with features of maternal nesting behaviour to shape the developmental environment. Here, we measure thermal profiles in 86 nests at two geographically distinct sites in the northern and southern regions of the American alligator's (Alligator mississippiensis) geographical range, and examine the influence of both climatic factors and maternally driven nest characteristics on nest temperature variation. Changes in daily maximum air temperatures drive annual trends in nest temperatures, while variation in individual nest temperatures is also related to local habitat factors and microclimate characteristics. Without any compensatory nesting behaviours, nest temperatures are projected to increase by 1.6-3.7°C by the year 2100, and these changes are predicted to have dramatic consequences for offspring sex ratios. Exact sex ratio outcomes vary widely depending on site and emission scenario as a function of the unique temperature-by-sex reaction norm exhibited by all crocodilians. By revealing the ecological drivers of nest temperature variation in the American alligator, this study provides important insights into the potential consequences of climate change for crocodilian species, many of which are already threatened by extinction.

Ant colony nest networks adapt to resource disruption.

Animal social structure is shaped by environmental conditions, such as food availability. This is important as conditions are likely to change in the future and changes to social structure can have cascading ecological effects. Wood ants are a useful taxon for the study of the relationship between social structure and environmental conditions, as some populations form large nest networks and they are ecologically dominant in many northern hemisphere woodlands. Nest networks are formed when a colony inhabits more than one nest, known as polydomy. Polydomous colonies are composed of distinct sub-colonies that inhabit spatially distinct nests and that share resources with each other. In this study, we performed a controlled experiment on 10 polydomous wood ant (Formica lugubris) colonies to test how changing the resource environment affects the social structure of a polydomous colony. We took network maps of all colonies for 5years before the experiment to assess how the networks changes under natural conditions. After this period, we prevented ants from accessing an important food source for a year in five colonies and left the other five colonies undisturbed. We found that preventing access to an important food source causes polydomous wood ant colony networks to fragment into smaller components and begin foraging on previously unused food sources. These changes were not associated with a reduction in the growth of populations inhabiting individual nests (sub-colonies), foundation of new nests or survival, when compared with control colonies. Colony splitting likely occurred as the availability of food in each nest changed causing sub-colonies to change their inter-nest connections. Consequently, our results demonstrate that polydomous colonies can adjust to environmental changes by altering their social network.

Are Sage‐Grouse Fine‐Scale Specialists or Shrub‐Steppe Generalists?

ABSTRACTSage‐grouse (Centrocercus spp.) are influencing rapidly evolving land management policy in the western United States. Management objectives for fine‐scale vegetation characteristics (e.g., grass height &gt;18 cm) have been adopted by land management agencies based on resource selection or relationships with fitness proxies reported among numerous habitat studies. Some managers, however, have questioned the appropriateness of these objectives. Moreover, it remains untested whether habitat–fitness relationships documented at fine scales (i.e., among individual nests within a study area) also apply at scales of management units (e.g., pastures or grazing allotments), which are many orders of magnitude larger. We employed meta‐analyses of studies published from 1991 to 2019 to help resolve the role of fine‐scale vegetation structure in nest site selection and nest success across the geographic range of greater sage‐grouse (C. urophasianus) and evaluate the validity of established habitat management objectives. Specifically, we incorporated effects of study design and functional responses to resource availability in meta‐regression models linking vegetation structure to nest site selection, and used a novel meta‐analytic approach to simultaneously model vegetation structure and its relationship to nest success. Our approach tested habitat relationships at a range‐wide extent and a grain size closely matching scales at which agencies make management decisions. We found moderate, but context‐dependent, effects of shrub characteristics and weak effects of herbaceous vegetation on nest site selection. None of the tested vegetation characteristics were related to variation in nest success, suggesting nesting habitat–fitness relationships have been inappropriately extrapolated in developing range‐wide habitat management objectives. Our findings reveal surprising flexibility in habitat use for a species often depicted as having very particular fine‐scale habitat requirements, and cast doubt on the practice of adopting precise management objectives for vegetation structure based on findings of individual small‐scale field studies. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Breeding biology of the White-headed Pigeon Columba leucomela in a modified landscape

Current knowledge of the breeding biology of the White-headed Pigeon Columba leucomela is derived mainly from observations of captive birds, with little published data on reproductive behaviour and breeding success in wild populations. Over 10 years (2001–2010), 122 nests were monitored in a rural landscape near Lismore, northern New South Wales. Nests were in a wide variety of trees and shrubs, including ornamentals, mostly <10 years old. Breeding Pigeons tolerated a high level of daily human activity, with many nests close to buildings, and with brooding birds sitting tightly in close proximity to working staff. Nests were re-used in all years, with ~65% of clutches laid in previously used nests. Individual nests were re-used multiple times, both within a season, and over multiple years. Clutches were laid in all months except October and November. Incubation and nestling periods and care are detailed. Body colour of fledglings and juveniles was variable, with the plumage of a minority having a striking resemblance to the Metallic Pigeon C. vitiensis . Overall breeding success for nests where the outcome was known was 38.5%. Predation, likely involving a range of taxa, was the largest single cause of nesting failure. White-headed Pigeons using a modified landscape with abundant seasonal fruit and seeds from the introduced tree Camphor Laurel Cinnamomum camphora demonstrate traits that facilitate rapid and extended breeding.