Kentish Plover(Charadrius alexandrinus) and Little Tern(Sternula albifrons) prefer shells for nesting:A field experiment

Shorebird populations are declining worldwide,mainly due to human disturbances and loss of coastal wetlands.However,supratidal habitats as saltpans could play a role in buffering human impact.Saltpans have shown to be important as feeding or breeding sites of some shorebird species.A potential conservation strategy to increase shorebird populations in saltpans is to manipulate the cues that birds use to select optimal breeding habitat.Here it is hypothesized that shorebirds are attracted to bivalve shells due to the advantages they offer.Following this hypothesis,we supplemented a restored saltpan in 2019 and 2021 with bivalve shells,expecting an increase in the number of breeding birds’ nests.More than 75% of Kentish Plover(Charadrius alexandrinus) and Little Tern(Sternula albifrons) nests were found in patches with shells in both years.The best model for both species indicates that the presence of shells is the factor that most correlates with the location of nests.The probability of choosing one place over another to settle their nest increases in areas with an abundance of shells,double in the case of the Kentish Plover and triple in the case of the Little Tern.The result of this study may constitute a valuable tool for attracting birds to restored saltpans and could contribute to the success of expensive restoration projects where time is usually a constraint.

Flexible nest site selection of the endangered Oriental Storks(Ciconia boyciana):Trade-off from adaptive strategies

Nest site selection is a vital component of bird reproduction success,and an adaptive behavior conducted to decrease nest predation risk with avoiding external disturbances.Understanding patterns of nest site selection can provide insights into how species adapt to changes in their habitat and has important conservation implications.In this study,we used microhabitat variables and multi-scale data with a field survey of nest occurrence to determine nest site selection patterns and adaptive strategies of the breeding Oriental Storks(Ciconia boyciana)in different nest areas.Results demonstrate that the nest site microhabitat characteristics of the breeding Oriental Storks significantly differed among the three nesting areas,and nest height was higher in the middle and lower Yangtze River floodplain than in the Northeast China and Bohai Bay nest areas.The food resources and intensity of human disturbance had the greatest effects on the nest site selection of the breeding Oriental Storks.The intensity of human disturbance was positively correlated with the nest height of the breeding Oriental Storks in Bohai Bay and the middle and lower Yangtze River floodplain;however,nest height decreased with the abundance of food resources in the Northeast China nest area.Our findings indicate that the nest site selection patterns of Oriental Storks showed flexible adaptive strategies.In safer environments,nests were lower and closer to food resources,which allows parent storks to invest more in the nestlings.However,in areas where human activity was intense,nests were higher to ensure the safety of their offspring.Some measures that could be taken to improve the breeding habitat of Oriental Storks include increasing the percentage of wetland areas in nesting areas to enhance food resources availability and setting artificial nests at suitable heights in potential nesting grounds to encourage nesting.Finally,the establishment of soft barriers around the nesting areas could increase the safety of nests.

The effects of climate and land use change on the potential distribution and nesting habitat of the Lesser Adjutant in Nepal

Climate change and land use change pose a threat to the world’s biodiversity and have significant impacts on the geographic distribution and composition of many bird species,but little is known about how they affect threatened large-sized waterbird species that rely on agricultural landscapes.To address this gap,we investigated how climate and land use changes influence the distribution and nesting habitats of the globally vulnerable Lesser Adjutant(Leptoptilos javanicus) in Nepal.Between 2012 and 2023,we collected distribution data from 24 districts and nesting site information from 18 districts.In a nation-wide breeding survey conducted in 2020,we documented a total of 581 fledglings from 346 nests in 109 colonies.The ensemble model predicted a current potential distribution of 15%(21,637 km2) and a potential nesting habitat of 13%(19,651 km2) for the species in Nepal.The highest predicted current suitable distribution and nesting habitat was in Madhesh Province,while none was predicted in Karnali Province.The majority of this predicted distributional and nesting habitat falls on agricultural landscapes(>70%).Our model showed a likely range expansion of up to 15%(21,573 km2) for the distribution and up to 12%(17,482 km2) for the nesting habitat under SSP5-8.5 scenarios for the 2070s.The range expansion is expected to occur mainly within the current distribution and breeding range(Tarai and some regions of Siwalk),particularly in Lumbini and Sudurpashchim provinces,and extend to the northern portions(Siwalik and Mid-hill regions) in other provinces.However,the current Protected Areas and Important Bird and Biodiversity Areas are inadequate for providing optimal habitats for the species.Although the model suggests range expansion,the use of such novel habitats is primarily contingent on the availability and protection of large-sized trees(particularly Bombax ceiba,observed in 65% of colonies) in agricultural regions where nesting occurs.Therefore,our research suggests that agricultural landscapes should be prioritized in management plans for the conservation of the Lesser Adjutant in Nepal.

Modelling the nesting-habitat of threatened vulture species in the caucasus:An ecosystem approach to formalising environmental factors in species distribution models

Abiotic factors play an important role in species localisation,but biotic and anthropogenic predictors must also be considered in distribution modelling for models to be biologically meaningful.In this study,we formalised the biotic predictors of nesting sites for four threatened Caucasian vultures by including species distribution models(wild ungulates,nesting tree species)as biotic layers in the vulture Maxent models.Maxent was applied in the R dismo package and the best set of the model parameters were defined in the R ENMeval package.Performance metrics were continuous Boyce index,Akaike's information criterion,the area under receiver operating curve and true skill statistics.We also calculated and evaluated the null models.Kernel density estimation method was applied to assess the overlap of vulture ecological niches in the environmental space.The accessibility of anthropogenic food resources was estimated using the Path Distance measure that considers elevation gradient.The availability of pine forests(Scots Pine)and wild ungulates(Alpine Chamois and Caucasian Goat)contributed the most(29.6%and 34.3%)to Cinereous Vulture(Aegypius monachus)nesting site model.Wild ungulate distribution also contributed significantly(about 46%)to the Bearded Vulture(Gypaetus barbatus)model.This scavenger nests in the highlands of the Caucasus at a minimum distance of 5–10 km from anthropogenic facilities.In contrast,livestock as a food source was most important in colony distribution of Griffon Vulture(Gyps fulvus).The contribution of distances to settlements and agricultural facilities to the model was 45%.The optimal distance from Egyptian Vulture(Neophron percnopterus)nesting sites to settlements was only 3–10 km,to livestock facilities no more than 15 km with the factor contribution of about 57%.Excluding the wild ungulate availability,the ecological niches of studied vultures overlapped significantly.Despite similar foraging and nesting requirements,Caucasian vultures are not pronounced nesting and trophic competitors due to the abundance of nesting sites,anthropogenic food sources and successful niche sharing.

Nest-site selection by the white-tailed eagle and black stork–implications for conservation practice

Background:Nesting trees and habitat represent the key factor underpinning stand selection by forest-dwelling birds.While two large European species–the black stork(Ciconia nigra L.)and white-tailed eagle(Haliaaetus albicilla L.)–are known to require old,large trees for nesting,we sought to investigate further by comparing species requirements at the levels of the nesting tree,nesting stand,and landscape.This entailed a detailed examination of forest features within circles of radius 15 m surrounding 16 and 19 trees holding the nests of storks and eagles respectively.The same parameters were also checked in the vicinity of 50 randomly-selected mature trees.Results:Our results indicate different nesting preferences,with the eagles entirely confining themselves to Scots pine(Pinus sylvestris L.)–a species also chosen by black storks,which nevertheless regularly favour pedunculate oak(Quercus robur L.).Both species select trees of greater girth than the random ones,but white-tailed eagles choose to nest in the vicinity of patches of mature old stands with a loose canopy,to the extent that nesting trees and surrounding trees are of similar ages.In contrast,black storks prefer“veteran”trees with low-set crowns that are much older than any others in their vicinity.Nesting trees of the eagles are away from roads and close to lakes,while black storks do not avoid roads.Conclusions:As the ages of nesting trees of both species are greater than ages at final cutting in this region’s managed forest,silvicultural measures will need to be adjusted,with small patches of forest spared,or larger areas as“islands”of old-growth.Likewise,as tending and thinning are engaged in,certain trees with horizontal branches will need to remain,with relict trees also left untouched.As it happens,all of these recommendations are anyway key elements of close-to nature silviculture and multifunctional forestry.

Nest site characteristics and nest loss of Marsh Grassbird at Zhalong National Nature Reserve, China

The Marsh Grassbird Locustella pryeri is an uncommon songbird endemic to East Asia. Suitable nest- site selection can minimize nest loss, especially for open- cup and ground nesting passerines. We located and mon- itored 66 Marsh Grassbird nests during 2004-2006 in Zhalong National Nature Reserve, northeast China, to identify characteristics of preferred nest sites. Marsh Grassbird nested mainly at sites with dense vegetation cover, high undergrowth and dry standing reed stalks, as well as small shallow ponds or rivers. Nests were more successful when they were placed higher above ground in patches with greater litter thickness. Predation and flooding were the leading causes of nest failure, accounting for at least 33 and 25 % of 24 nests lost, respectively. We ad- vocate retention of some unharvested reed patches and implementation of irrigation strategies that avoid increas- ing water levels during the breeding period （May-July） of Marsh Grassbirds.

Habitat selection by nestbox-breeding birds and Roe Deer are incongruent within a heterogeneous woodland landscape

Conserving species relies upon acquiring an understanding of their use of habitat,yet our understanding of the use of habitat by co-existing species of different guilds at microgeographic scales remains poor.In particular,the use of habitat by woodland species is of conservation concern because of widespread declines in woodland biodiversity.Woodland bird declines have been ascribed,in part,to high deer densities because their browsing reduces the availability of nesting sites and food.We quantify the microgeographic use of habitat by Roe Deer(Capreolus capreolus)and of Great Tits(Parus major),Blue Tits(Cyanistes caeruleus)and Pied Flycatchers(Ficedula hypoleuca)in a heterogenous woodland landscape.We examined the use of habitat at microgeographic scales by the deer and the three bird species in relation to whether the local habitat was flat or wet or had a path,fence or wall within a 25-m radius of 206 randomly selected locations.We first examined if the occupancy rates of nestboxes in those locations were correlated with the number of Roe Deer lays and second,examined if the use of habitat by the Roe Deer and the bird species were associated with each of the habitat features that we quantified.We begin by showing that the use of habitat by Roe Deer is incongruent with the use of habitat by Great Tits,Blue Tits and Pied Flycatchers during the breeding season.Also,whilst all three bird species showed no,or weak,habitat preferences,the Roe Deer preferred daytime lay sites that were in flat areas of wet woodland close to paths,whilst there were no significant effects of the presence of fences and walls.These findings show that the Roe Deer and the three bird species differ in the use of habitat within a heterogenous woodland landscape,meaning that their use of habitat did not overlap at microgeographic scales.Meanwhile,the deer showed preferences for flat areas of wet woodland,whilst none of the bird species exhibited such preferences,and we discuss the implications of our findings for the management of woodlands.

Nest Site Preference and Fidelity of Chinese Alligator (Alligator sinensis)

Oviparous female reptiles select nesting sites with optimal ecological factors that contribute to egg development. Chinese alligator （Alligator sinensis）, an oviparous reptile, is a critically endangered crocodilian with temperature-dependent sex determination. Research on its nesting behavior may facilitate the protection of this species. In this study, we monitored nesting behavior over eight years. We compared selected frequency of nest sites, distance from nest site to water, height from nest site top to the water surface, distance from nest site to human activity region, and canopy density between nest sites on the island and bank. The results showed that 45 nest sites were used by female alligators over eight years and each site was selected from one to 10 times. The selected frequency of nest site occurrence on the island was higher than that on the bank （P 〈 0.001）. We observed that 88% of the individual alligators （15/17） showed different degrees of nest site fidelity. However, Chinese alligators might not always be loyal to only one nest site because of environmental changes or interspecific competition at nest sites. Our findings suggest that female alligators prefer to nest at island, which might be because of the nests on the island had a higher canopy density （P = 0.010） and were further from the human activity region （P 〈 0.001） than those on the bank did. It would be beneficial to reduce human activities during the breeding season and protect the vegetation of Chinese alligator habitats in the future.

Nest site tenacity and mate fidelity in the Black-headed Gull(Chroicocephalus ridibundus)

Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.

Nest distribution and nest habitat of the Tibetan Partridge(Perdix hodgsoniae)near Lhasa,Tibet

Background: Little is hitherto known about the breeding ecology of the Tibetan Partridge(Perdix hodgsoniae)which is endemic to the Tibetan plateau. Here we describe nest densities, inter-nest distances and general nest site characteristics in this gallinaceous bird species and explore the possibilities that certain shrub and plant types are preferred as nest surroundings.Method: A total of 56 nests were found over three breeding seasons near Lhasa, Tibet. Nest site characteristics were compared with random control plots and the proportions of specific plant species covering nests were compared with their estimated general occurrence in the study area.Results: Nest density in the two years with highest search effort was estimated at 1.43/km2 and 1.04/km2 but was clearly higher in the part of the study area facing north(1.86–2.35/km2) than that facing south(0.11–0.34/ km2). The average nearest neighbour distance of nests was about 300 m. Nests were situated in relatively lush vegetation and covered by a total of eight shrub species and three herbs. In contrast to previous reports, Caragana shrub did not constitute an important part of the nest habitat. The flowering, non-thorny bush Potentilla fruticosa was significantly over-represented as nest cover, while Rhododendron nivale was similarly under-represented. Nest bush foliage covered a larger area of ground, and the shrub surrounding nests was generally denser, than in control samples. Also, nests were placed closer to paths and in areas with lower densities of Yak(Bos grunniens) dung than in control samples.Except that soil temperatures were lower on nest sites than on control sites, micro-climate variables measured in this study did not differ between nest sites and control plots.Conclusions: Opportunity for nest concealment is probably an important quality of the nest habitat in Tibetan Partridges, yet it is unclear why the species should prefer P. fruticosa as nest cover. It is possible that nest sites are chosen to secure escape exits in the case of approaching predators and to reduce the risk of nest trampling.Tibetan Partridges may also select nest sites according to micro-climate, either directly or indirectly through climate-related differences in shrub vegetation.

Eastern wild turkey nest site selection in two frequently burned pine savannas

Introduction:Reproductive success is a critical factor affecting avian demographics and can be influenced by many factors including nesting chronology,predation risk,and fine-scale nest site selection.Methods:We modeled the relative influences of habitat-related covariates at six spatial scales(nest site:15-,40-,80-,120-,160-,and 200-m radii)on Eastern wild turkey(Meleagris gallopavo silvestris)nest site selection in two pine savannas managed by frequent prescribed fire(≤3 years)in southwestern Georgia during 2011-2013.Results:Nest site(15-m scale)habitat metrics(mean visual obstruction[cm]and canopy closure[%])had the greatest influence on nest site selection relative to covariates measured at larger spatial scales.Scaled odds ratios suggested that nests were 26.8% more likely to occur for every 10 cm increase in mean vegetation height with a range of 7.5 to 150.0 cm and 18.5% less likely to occur for every 10% increase in canopy closure with a range from 0.0 to 97.8%.Total ground cover,canopy closure,edge density,and percent land cover type(e.g.,mature pine,mixed pine/hardwood,shrub/scrub)had minimal influence on nest site selection.Conclusions:Management of pine savannas for turkey nest sites should focus on creating early-successional vegetation to conceal nests from potential predators.Additionally,we suggest that future studies consider evaluating the influence of spatial scale on turkey nest site selection.

Number and nest-site selection of breeding black-necked cranes over the past 40 years in the Longbao Wetland Nature Reserve,Qinghai,China

Black-necked crane(Grus nigricollis,BNC),facing serious threats from human activities and habitat variations,is an endangered species classified as vulnerable under the revised IUCN Red List.In this article,we investigated and analyzed the population and nesting microhabitat of BNCs in the Longbao National Nature Reserve(NNR)from 1978 to 2016,and found the number of BNCs increased from 24 in 1978 to 216 in 2016.This establishment of the Longbao NNR represented the activities of protecting endangered animal species are effective.However,the land cover classification results of Landsat images showed that the marsh wetland,which was the BNC’s primary habitat,decreased during 1978–2016,while artificial buildings increased,which affected the habitat of BNCs.The increase in average temperature over the past 40 years has also had an impact on the number of BNCs.BNCs preferred to nest in marsh wetlands or on islands with open water or star-like distributions through observation.The results of the principal component analysis showed that the nearest distance between nests and habitat type were the primary factors influencing nesting site selection.To protect BNC,we suggest decreasing wetland fragmentation,reducing habitat degradation and providing an undisturbed habitat.