Nest Sites Research Articles

Importance of Mesohabitat for Nest-Site Selection in Breeding Eagle Owls (Bubo bubo): A Multi-Scale Model

Apex predators make excellent bioindicators of habitat quality and anthropogenic changes. Eagle owls (Bubo bubo) are such apex and keystone predators, who show preferential nest-site selection, usually away from human activities and habitation. However, Israel is a small country with a burgeoning human population. Hence, in order to understand the habitat requirements of eagle owls in central Israel, we conducted a multi-scale model analysis on their existing nest sites between 2006 and 2010. We identified 203 successful breeding attempts at 73 different sites. Our data suggested that the breeding population of the eagle owls was limited by the availability of quality nest locations, i.e., quarries, and caves. The probability of an eagle pair breeding increased with the presence of both quarries and caves, but was not related to mesohabitat properties. In addition, eagle owl breeding densities were positively related to the number of nest localities and to the planted woodlands. Furthermore, we found that eagle owls successfully raised their young regardless of the surrounding mesohabitat and sought the presence of other potential nest sites in the vicinity of the active nest sites, most likely due to the owls’ opportunistic and generalist hunting behavior, which facilitated the consumption of a wide prey base. Appropriate nest sites (quarries and caves) appeared to increase population numbers and, therefore, should be protected Further studies should determine whether increasing artificial nest sites and reclaiming abandoned quarries could increase eagle owl numbers in a sustainable manner.

Combining bio-telemetry and underwater imagery to elucidate the reproductive behaviour of a large, long-lived Australian freshwater teleost

Murray cod Maccullochella peelii (Mitchell) have a key ecological role in ensuring the health of Australia's largest inland waterway, but many aspects surrounding its reproductive strategies in the wild are unknown. From 2015 to 2019 within the Northern Murray-Darling Basin, Australia, we used a combination of bio-telemetry and underwater imagery to quantify the behaviour of Murray cod across their breeding cycle in a natural riverine environment. In most years, breeding behaviour including nest site selection was observed from early-August and spawning from late-August through to late-October, which is considerably earlier than previously reported. There was a positive correlation between the onset of breeding behaviour and week-of-year, and spawning was correlated with moon-phase. Whilst some nesting sites were amongst woody debris and in hollow logs, the majority were located in shallow water on hard substrate underneath undercuts along the riverbank edge. Nests were frequently established in isolated and disconnected pools with little or no measurable flow, suggesting that river hydraulics is not a key component driving spawning of Murray cod across at least some areas of its range. Larvae were observed actively swimming and controlling their position within and near nests and used a scatter tactic when dispersing. We also established that disturbing nesting Murray cod had a negative impact on egg and larval survival. We suggest a review of current regulations to safeguard the long-term conservation of the species across all sections of its range.

Wetland Habitat Characteristics Predict Nest Site Selection of American Alligators (Alligator mississippiensis) in an Inland Freshwater Ecosystem

Habitat characteristics can have large effects on nest site selection of oviparous vertebrates. It is thought that habitat preference in many species is driven by natural selection because of habitat-specific fitness consequences. However, long-term studies on nesting of oviparous reptiles, in particular, are less common in comparison with other nesting vertebrates. As a result, specific habitat associations that define nesting habitat for many species are largely unknown. We studied habitat characteristics and selection of American Alligator (Alligator mississippiensis) nest sites in inland freshwater wetlands. We investigated the habitat characteristics associated with 112 nests studied during the 2013–2019 nesting seasons, and quantified habitat characteristics in relation to nest locations and random points. A nearest neighbor analysis indicated that American Alligator nests are not randomly distributed across wetlands, but are more representative of a clumped spatial distribution, suggestive of habitat preference and site selection. We measured habitat variables such as wetland vegetation cover, average water depth, island density, bank slope, canopy cover, and wet bulb globe temperature, as well as alligator population demographics such as relative adult proportion, at each nest and random site. Subsequently, we found that the best variables for predicting American Alligator nest site selection included island density, slope of bank, canopy cover, and wet bulb globe temperature. The best predictive model demonstrated that the odds of nest site selection increased with increasing canopy cover, wet bulb globe temperature, island density, and decreasing bank slope. These habitat choices presumably reduce the risk of nest predation and provide thermal cover for proper balance of nest site microclimate. Based on our results, practices focused on alligator nesting habitat should consider these specific habitat characteristics in outlining applied strategies and working toward management and conservation goals.

Bacterial Isolates Derived from Nest Soil Affect the Attraction and Digging Behavior of Workers of the Red Imported Fire Ant, Solenopsis invicta Buren.

Simple SummaryPopulations of the red imported fire ant (Solenopsis invicta) are found throughout the southern United States. Because these invasive ants sting and are highly territorial, they are hazardous to people and livestock and are detrimental to native ant populations. Control of this species generally relies on insecticidal baits that attract and kill the ant. The aim of our study was to determine if bacteria cultured from S. invicta nest soils affected worker ant behaviors and whether the bacteria were attractive or repellent to the ants. Bacterial isolates cultured from nest soils were used in binary choice bioassays that tested for effects of bacterial species and bacterial concentrations on worker ant digging and residing preferences. Arthrobacter woluwensis (Actinobacteria) attracted worker ants while bacteria identified as Firmicutes generally repelled ants. This study provides a basis for the identification of new biologically derived compounds that can be used to alter behaviors of the red imported fire ant and be implemented in novel control strategies.Populations of monogyne and polygyne red imported fire ants (RIFA), Solenopsis invicta Buren, are distributed throughout the southern United States. This ant species is hazardous to farm animals and workers, damages infrastructure, and depletes native arthropod populations. Colony expansion is affected by several biotic factors, but the effects of soil microbes on ant behavior related to soil excavation within nest sites have not been investigated. Consequently, we cultured bacteria from RIFA nest soils. The effects of individual bacterial isolates and bacterial cell densities on the choice of digging site as well as digging activity of monogyne and polygyne RIFA worker ants were evaluated in two-choice bioassays. Based on phylogenetic analysis, 17 isolates were selected and tested initially at 5 × 108 cells/mL and 20 workers per assay. Firmicutes (Bacillus, Paenibacillus, Brevibacillus) repelled the ants, but Arthrobacter woluwensis strongly attracted ants. Subsequently, the six isolates having the greatest positive or negative effects on ant behavior were evaluated at a lower bacterial cell and worker ant densities. Ant responses to these bacteria generally decreased as cell densities declined to 5 × 106 cells/mL. Observations of ant behavior during a three-hour, two-choice bioassay revealed that ants generally visited both control and bacteria-treated sand prior to making a digging site choice. Our research results indicate that soil bacteria may mediate ant nest expansion or relocation and foraging tunnel construction. Identification of bacterial metabolites that affect RIFA digging behavior merits additional research because these compounds may provide a basis for novel management strategies that repel RIFA away from sensitive infrastructure or attract fire ants to insecticidal baits.

Nest site selection and breeding ecology of the red-billed blue magpie Urocissa erythrorhyncha in central China

Abstract While knowledge on birds’ breeding ecology is essential for understanding avian adaptation and managing conservation, it is poorly studied for many species, even for some common species. The knowledge of the natural history of the red-billed blue magpie (Urocissa erythrorhyncha), a species widely distributed in China and Southeast Asia, is sketchy. Here we present detailed data of nest site selection and the breeding ecology of red-billed blue magpie in central China, and of the effects of nest predation and brood parasitism on reproductive strategies. Most nests were built on Phyllostachys sulphurea and Quercus acutissima. Breeding season ranged from March to August. The first egg was laid between early April and late July. The incubation period lasted 15 days and the nestling period, 18 days. Average clutch size was 4.6 eggs, and brood size at fledging was 3.3 young. Overall, 43.8% of nesting attempts successfully produced at least one fledged young. Nest predation and brood parasitism were the two main reasons for fledging failure, which mainly occurred after April. Correspondingly, U. erythrorhyncha showed a tendency to build nests higher up and have a smaller clutch size in late stages of the breeding season. This study provides the first reliable and comprehensive information on the reproductive parameters of U. erythrorhyncha, which will lay a foundation for further understanding this species’ biology and opens up an avenue for large-scale comparative studies of the Urocissa genus or higher-level taxa.

Spatial distribution of potential wild turkey nest predators in west‐central Louisiana

AbstractWild turkey nest success is variable spatially and temporally, with predation being the primary driver of nest loss. Historically, characteristics of nest site vegetation have been used to predict the probability of a nest being successful, a corollary to not being preyed upon. Implicit in nest success studies is that the density, distribution, and habitat preferences of predator species, relative to wild turkey nest distribution, drive the predation risk of nests on the landscape. We quantified diversity of wild turkey nest predator species within 11‐ha incubation ranges centered on active nest sites, scent baited passive nest sites, and scent baited and unbaited random sites and developed a spatially explicit predictive model for potential nest predator distribution based on vegetation and landform characteristics that occurred within incubation ranges. We used 210 camera sites on passive (nesting area from previous year), active (nesting area same year), and random sites over 5,144 trap nights (TN) and recorded 2,925 photographs of potential nest predator species. Relative abundance indices (RAI) indicated greater abundance in passive (14.2/100 TN) and active (12.7/100 TN) nesting sites relative to random sites (3.13/100 TN). For active nesting sites, successful nests had lower RAI (1.8/100 TN) than unsuccessful nests (10.4/100 TN) and lower RAI than baited and unbaited random sites (2/100 TN and 4.3/100 TN, respectively). Our results indicate that potential wild turkey nest predator species regularly occurred within incubation ranges, but were more likely to occur in locations with nests than in random locations on the landscape. We did not document a strong relationship between potential nest predator occurrence and spatial vegetation metrics, which do not appear to affect the occurrence of generalist potential predator species. However, we did show evidence of avoidance by certain potential predators for certain vegetation types. Thus, our work indicated that the most important factor affecting a nest's outcome may be the placement of the nest on the landscape relative to use by potential predator species. We suggest future research evaluate how vegetation characteristics within wild turkey incubation ranges impact nest predator use.

Nest site fidelity and nesting success of female wild turkeys

AbstractNest site fidelity is a common behavioral trait among birds that can positively influence reproductive success when there is spatial heterogeneity and temporal predictability in nest site quality. Nest site fidelity in wild turkeys (Meleagris gallopavo) has received little attention in the literature despite providing a potential link to nesting success. We used data from 32 female wild turkeys across 8 field sites ranging from South Carolina to Texas with 2 consecutive years of nest data to determine if females showed fidelity to nest sites, if distance between nest locations in consecutive years predicted nest success in the second year, and if females showed fidelity to specific areas within home ranges (patches) for nesting. Females tended to nest closer to previously successful nests (median distance = 920 m) than to unsuccessful nests (median distance = 1550 m) in the second year; however, we documented no evidence of fidelity to specific nest sites. There was widespread reuse of prelaying (89.5%) and laying (77.8%) ranges by females between years, indicating some evidence for patch fidelity. The lack of evidence for nest site fidelity may be a result of the temporally dynamic nature of turkey nesting cover and ubiquity of predation risk across the southeastern U.S, which ecological theory predicts would not provide the reproductive benefits of fidelity that hinge on predictability. Fidelity to patches within home ranges may represent an always‐stay approach, which is expected when the cost of dispersing to new breeding areas outweighs potential benefits and may allow females to draw on prior knowledge of areas within their home ranges. Although distance between nests was not a significant predictor of nest success, females that nested successfully in the first year had a probability of 0.63 of successfully nesting in the second year, whereas unsuccessful females had probability of success of 0.08 in the second year. The tracking of individual nesting success across years warrants further research, as our results imply that a disproportionate percentage of reproduction through time may be attributed to a subset of females that are consistently successful, which may have implications for our understanding of reproductive dynamics in low productivity populations.

Linking wild turkey hen movement data to nesting behavior

AbstractMonitoring of wild turkey (Meleagris gallopavo) females to obtain representative measures of apparent nesting and nest survival rates has long been an important component of wild turkey management. In the interest of improving estimates of apparent nesting and nest survival rates, we assessed the feasibility of inferring reproductive behavior of wild turkeys from remotely acquired movement data. We ascertained detailed nesting stage chronologies using Global Positioning System (GPS) data downloaded from 44 females fitted with transmitters that had both a very high frequency (VHF) beacon and a GPS logger. Then we tracked females using VHF to confirm nest locations and nest fate in north and north‐central Florida. Using twice hourly GPS derived locations, we evaluated 3 predictive machine learning models (Chi‐squared automatic interactive detection [CHAID], exhaustive CHAID, and multivariate adaptive regression splines [MARSpline]) for their ability to accurately classify nesting behaviors (laying and incubating stages) that were confirmed via visual inspection of all potential nest sites. Incubation stage was readily identifiable by the spatial signatures present in each female's GPS‐based movement track across all models (up to 92% true positive and as low as 8% false positives in exhaustive CHAID models), whereas the laying stage was more difficult to identify (up to 65% true positive and as low as 35% false positives in exhaustive CHAID models). Daily averages of movement metrics generally achieved better performance in predictive models than data sets with more frequent sampling (i.e., 30‐minute daytime locations). Our results indicated that exhaustive CHAID models performed best in identifying nesting stages, using movement metrics from GPS data. With continued development, these models may facilitate and improve large‐scale wild turkey monitoring.

Do soil density and humidity affect nest‐founding in leaf‐cutting ant queens?

AbstractThe habitat choice of nest sites by founding queens of leaf‐cutting ants varies with abiotic factors such as temperature, soil density, and soil humidity. In this study, we tested the hypothesis that soil density and moisture affect excavation effort (i.e., excavation period, excavated soil amount, initial nest depth, initial chamber volume, and mortality) in queens of the leaf‐cutting ant Atta sexdens (L.) (Hymenoptera: Formicidae). Queens were placed in experimental areas in three natural soils in Brazil with varying density and moisture content. The excavated soil was collected, dried, and weighed, and digging period, nest depth, chamber volume, and queen mortality were evaluated after nest establishment. In artificially shaded habitats (less dense and more humid soil), the establishment of queens was greater, the period of nest foundation was shorter, and excavated soil amount, nest depth, and volume of the initial chamber were greater than in forest and pasture habitats (denser and drier soils). Also, queen mortality was lower in less dense, more humid soil. This indicates a trade‐off between maximizing the depth of the nest, to increase protection against inadequate environmental conditions, and minimizing energy expenditure during excavation, affecting their survival.

Diet and reproductive success of Great Horned Owl (<i>Bubo virginianus</i>) at its northern breeding limit

We studied the diet and reproductive success of Great Horned Owl (Bubo virginianus) at its northern range limit during an apparent high in the Snowshoe Hare (Lepus americanus) population. We performed diet analyses using images from fixed motion sensor cameras and pellet and prey remains collected at active nests, and gathered data on breeding success through camera and visual observations. Pellet data at 14 nests produced 1277 prey records consisting of 65–95% Snowshoe Hare biomass. Great Horned Owls ate 18 different prey types, with overall biomass consisting of 93% mammal, 7% bird, and less than 1% insects, frogs, and fish. The mean prey mass of 714 g (± 34 SE) was 2–25 times the mean prey mass of studies of this species at more southerly latitudes. Camera observations showed that Great Horned Owls delivered an average of 459 g/chick/d (± 75) throughout nesting. This was significantly (P = 0.005) higher than observations from Alberta, at 328–411 g/chick/d. Pellet/prey remains data showed that Great Horned Owls delivering a higher proportion of hares to their nestlings successfully raised more chicks (χ21 = 6.3, P = 0.012), highlighting the importance of this prey in the population dynamics of Great Horned Owl. In addition, we observed Snowshoe Hare removing pellets beneath nest sites, revealing an apparently undocumented bias to the use of pellet analysis.

Infanticide by the White-throated Cacholote (Pseudoseisura gutturalis) in the Monte Desert, Argentina

We documented a case of nonparental infanticide at a nest of White-throated Cacholote (Pseudoseisura gutturalis) in 2018 in xeric northwestern Argentina, the first confirmed for the large family Furnariidae. Competition for resources such as food or nest sites, rather than cannibalism or short-term mating opportunities, may underlie this event.

Do Red-cockaded Woodpecker (Dryobates borealis) cavity locations provide olfactory concealment from predators?

Nest site selection is crucial for survival and fecundity of birds. Predators find nests using visual, aural, thermal, and olfactory cues, yet few studies have evaluated olfactory concealment of nests. Rat snakes (Pantherophis spp.) are common nest predators that use ground-level olfactory cues to detect nest locations. In Arkansas, USA, we evaluated if cavity locations of the Red-cockaded Woodpecker (Dryobates borealis, RCW), a species that experiences nest predation by rat snakes, were associated with airflow conditions known to provide olfactory concealment for other bird species. We used a 3-dimensional sonic anemometer to measure ground-level air velocity, turbulence, and turbulence intensity at cavity trees and unused trees, and at cavity and opposite orientations on trees. For all airflow variables, we found no differences between used and unused trees and orientations. Other factors such as landscape-scale vegetation cover, forest stand structure, and tree characteristics may be more important for providing visual concealment or optimal foraging conditions. However, it remains possible that such factors also convey olfactory concealment. For example, savannah-like forests preferred by RCWs may have greater air turbulence than closed forests. Further research on RCWs and other bird species to address additional aspects of olfactory concealment, and relationships between different dimensions of concealment (e.g., between visual and olfactory concealment), would give insight into how habitat management could provide multiple benefits to birds.

The location of thrush nests on buildings affects the chance of cowbird parasitism

Nest site placement is a critical choice among passerines, being an important factor that affects their breeding success. In urban areas, human buildings offer suitable nesting sites usually less exposed to predators and brood parasitic birds and readily available to be reused for several breeding seasons. However, the extent to which the features of nest placement sites in buildings contribute to reduce nest detectability by predators and brood parasites is still unknown. Here, we tested whether the features of the nesting site (i.e., lateral concealment, distance to the building ceiling, and height above ground) affect the chance of brood parasitism by Shiny Cowbirds (Molothrus bonariensis) in Pale-breasted Thrushes (Turdus leucomelas) nests placed on buildings in a Brazilian suburban area from 2013 to 2019. Cowbird parasitism increased throughout the study years, and nests closer to ceilings, supposedly better concealed, were more likely to be parasitized. Laying date, height above ground, and lateral concealment were not related to the probability of cowbird parasitism. We suggest that less concealed nests enhance vicinity monitoring by parents, allowing a faster agonistic response to the presence of cowbirds near the nest. Our results indicate that nest site location in cities may have consequences for the breeding success of cowbird hosts.

Wind Farms and Power Lines Have Negative Effects on Territory Occupancy in Eurasian Eagle Owls (Bubo bubo).

Simple SummaryWind power can contribute to a necessary reduction in CO2 and other greenhouse gas emissions. However, wind farm construction and infrastructure might cause other problems, for example, reducing biodiversity. In parts of their distribution area, eagle owls are scarce and declining, and not much is known about their tolerance for different kind of disturbances. Here, we investigated the presence–absence of Eurasian eagle owls (Bubo bubo) in 48 territories in the central part of Norway before the construction of eight wind farms and power lines started, and shortly after the construction period. Eagle owls living within 4–5 km away from the disturbance left their territories to a higher extent than eagle owls living even further away.Wind power is useful for reducing greenhouse gas emissions, but the construction and operation might have negative effects on biodiversity. The purpose of this study was to investigate any effects of wind farm and power line construction on territory occupancy in the vulnerable Eurasian eagle owl. We investigated 48 eagle owl territories before and after the whole construction period and a short operation period with the use of sound meters. We found that territorial eagle owls within 4–5 km from the wind farm and power line construction disturbance left their territories to a significantly higher extent (41% reduction in the number of territories with eagle owls) compared with the eagle owls in territories further away (23% reduction). The distance from the nest site to the disturbance was significantly shorter for those territories that were abandoned compared with territories where the birds stayed. Possible reasons for this decline might be a higher mortality caused by collisions, desertion and avoidance of wind power areas caused by the noise and disturbance from their construction. In addition, there are possible indirect effects, for example reductions in prey species may force eagle owls to abandon their territories. The construction period lasted much longer than the period with active wind turbines and power lines in this investigation, but we cannot separate the effects of the two because the investigations were only possible in the eagle owl breeding season, and the wind turbines were activated shortly after the construction period. Our results imply that careful investigations are needed to detect the possible occurrence of eagle owls near any type of construction work. Studies of these territories should strongly influence how and when the construction work can be carried out, but more investigations are needed to find details about the influence of distance.

Notes on Mexican Woodnymph (Eupherusa ridgwayi) Behavior and Nesting in Central-western Mexico

The Mexican Woodnymph (Eupherusa ridgwayi) is endemic to west-central Mexico with a narrow distribution range and relatively small population size. The species nest, nesting activities and nestling's characteristics were unknown until now. We generated a map of this species using data from BirdLife International, the Global Biodiversity Information Fund database, e-Bird, and the Naturalista. We used the Mexican Woodnymph records in Jalisco and projected them on a vegetation map. We documented a female constructing a nest, later nesting, until the nestlings flew out of the nest in the cloud forest in central-western Mexico: Jalisco state. The nest site was characterized and the materials used for the nest construction were determined. In addition, we documented several observations made on territorial and foraging behavior.

Ghost crab predation of loggerhead turtle eggs across thermal habitats

The reproductive success of sea turtles is highly influenced by the environmental and biological conditions of the nesting beach. Maio Island, Cabo Verde, one of the main nesting sites for the Northeast Atlantic loggerhead subpopulation, displays marked heterogeneity of sand coloration, with dark, mixed and light sandy beaches, resulting in different thermal habitats. Considering that sand temperature can influence both sea turtle embryo development and predatory activity by ghost crabs – the main predators of clutches and hatchlings at Cabo Verde – we surveyed loggerhead nesting beaches at Maio Island, with three sand colorations (‘beach type’), to assess: 1) the density and size of ghost crab burrows, as a proxy for ghost crab density and size, and 2) ghost crab predation on 70 loggerhead nests. We further assessed nest site selection, by considering the number of nesting activities and clutches laid across beach type. There were no evident trends in the distributions of ghost crab density and size between years or beach type. We found that ghost crab predation is a major source of mortality in Maio Island, affecting 67.8% (n = 59) of the nests. Ghost crab predation was variable between beaches, but generally, at the warmer dark sand beaches, clutch mortality was mostly caused by ghost crab predation (53.2%, n = 17), while at the mixed sand beaches mortality by predation was low (7.5%, n = 18), compared to mortality due to other causes (49.9%), indicating that other factors can also significantly impact clutch survival. The mixed sand beaches had more nesting activities and higher nest density (2.29/m2; 1.25/m2, respectively), compared to the light sand (0.72/m2; 0.35/m2) and the dark sand beaches (0.73/m2; 0.27/m2), suggesting a possible predation-free nesting preference. Our findings show that some beaches are in need of nest protection, thus we recommend both in situ nest protection and egg translocation to safe hatcheries, depending on the threats identified, to enhance clutch survival at such heterogeneous nesting areas as Maio Island.

Nest sites used for daytime rest in urban Garden Dormice (Eliomys quercinus) in Wiesbaden, Germany

Garden Dormouse (Eliomys quercinus) populations have declined by 50% throughout Europe over the last 30 years. They are increasingly found in German cities, but little is known about their urban lifestyle. A radiotelemetry study was performed in the city of Wiesbaden, to investigate the daily resting habits of Garden Dormice. The location and structure of nest sites used for daytime rest (DNS) of five individuals (one female, four males) were recorded each to every second day during the months of May to July 2021. The animals were located 90 times in total in a DNS, and two to six different DNS per animal were identified. DNS were found in hedges, trees, bird nests, facade greening, nest boxes, and inside buildings. Garden Dormice in this study were often located in DNS that provide consistent temperatures (false floors, walls) and a high degree of protection from predators. DNS with visual cover and possible food supply (facade greening, hedges) were also often used. The frequency with which DNS were changed varied greatly depending on the individual. The dormice in this study showed adaptations to urban living, as each animal used at least one anthropogenic structure as DNS. Recommended conservation measures for Garden Dormice in urban areas, based on this study, include raising public awareness and protection and promotion of facade greening (climbing plants on walls and fences), hedges and old buildings. Further research on the life of Garden Dormice in urban areas is needed.

Habitats change habits: How Garden Dormice cope with different environments in Germany

The Garden Dormouse is currently disappearing from parts of its range. While its population is declining in many parts of Germany including forest habitats in low mountain ranges, a stable occurrence is found in some cities. A radiotelemetry study was performed in the spruce forests of the Harz National Park (mountains) and the city of Wiesbaden to compare space and habitat use, and the structure and use of daytime nest sites (DNS) used for rest. In total, eight individuals (5 males, 3 females) were tracked between May and September 2021. They used smaller home ranges in the city (MCP100: 2.39 ± 1.34 ha; n = 4) than in the forest (MCP100: 4.56 ± 3.13 ha; n = 4). At night, the animals used structures offering protection from predators and providing food like wide hedges in the city and rock crevices and berry bushes in the forest. The animals were located in a DNS a total of 133 times, and one to ten different DNS per animal were identified. They were situated in structures providing a high degree of protection from predators and also had consistent temperatures (e.g. rock crevices , deadwood piles , hedges, vines on buildings, nest boxes, and buildings). While females rarely changed their DNS, males used several of them. Recommended conservation measures for Garden Dormice include raising public awareness and also the protection and promotion of facade greening, hedges and old buildings in urban areas. A dense rocky cover, as well as a well-developed shrub layer with raspberry bushes are valuable in spruce woodlands .

Increasing Arctic Tundra Flooding Threatens Wildlife Habitat and Survival: Impacts on the Critically Endangered Siberian Crane (Grus leucogeranus)

Climate change is causing Arctic temperatures to increase at least twice as fast as the planet on average. Temperature and precipitation are predicted to continue increasing, such that flooding might become more prevalent in the new Arctic. Increased flooding frequency and extreme flooding events may pose new threats to Arctic biodiversity through habitat disturbance and decreased survival. We used the Siberian crane (Grus leucogeranus) as a model organism to investigate how flooding influences nesting habitat availability and juvenile counts. When spring flooding destroys eggs, adults either do not raise any chicks or have reduced time to prepare them for their long migration to China, thus years with extensive flooding could negatively impact future crane generations. We used nest site observation data from 14 surveys between 1995 and 2019, habitat mapping based on Landsat 8 imagery, and species distribution modeling to predict Siberian crane potential nesting habitat. Nesting habitat loss due to extreme flooding was calculated by overlaying this potential nesting habitat with Global Surface Water data. The percent of potential flooded nest sites varied between 6.7–55% across years, with a significant increase between 2001 and 2018. Extreme flood events, as experienced in 2017 and 2018, eliminated almost half of the potential nesting habitat. Importantly, we found that the percentage of flooded nest sites across years was negatively correlated with the number of observed juveniles. The Arctic lowlands are exposed to seasonal water level fluctuations that species have evolved with and adapted to. Siberian cranes and other species depending on Arctic ecosystems are expected to continue adapting to changing flood conditions, but extreme flood events further threaten the long-term survival of critically endangered species. It is imperative to assess how ecosystems and species respond to climatic extremes to support Arctic conservation strategies.

Effects of nest site selection and nest concealment on nest survival of Gosling's Bunting (Emberiza goslingi)

Selecting nest sites that provide access to resources and reduce predation risk is crucial to maximizing fitness in breeding birds. Therefore, understanding what habitat features influence nest site selection and nest success is a key component of avian conservation because it allows for identification and protection of habitat that will promote population growth. We examined drivers of nest success in Gosling's Bunting (Emberiza goslingi) by evaluating variables that influence nest site choice and nest survival at 23 nests and an equal number of random, paired, non-nesting locations in a tropical savannah landscape in north-central Nigeria. Gosling's Buntings exhibited a nonrandom nest-placement pattern. Nests were either on or in proximity to large rock surfaces with nesting probability increasing when the immediate nesting area (100 m radius around the nest) consisted of 30–60% bare rock. Compared to random non-nesting sites, buntings selected areas that were low in litter cover and/or had short grass height. Daily nest survival probability was high (0.96) and was positively associated with the proportion of bare rock around the nest but negatively with the amount of litter cover. Although hatching success was 56.9%, only 30% of all nesting attempts successfully fledged a chick suggesting that nest failure occurred mostly at advanced stages of nesting (nestling phase) when renesting is less likely. Nest survival was higher at low concealment, but only significantly higher than nest failure within a restricted concealment range of 45–54%. Our findings show that microhabitat features could benefit reproduction and daily nest survival. Furthermore, by linking nest-site attributes with fitness indices, we highlight the potential importance of fitness measures as a key component of habitat quality assessment for these buntings in tropical savannahs.