Number Of Breeding Pairs Research Articles

Breeding Success of Cape Vultures (Gyps coprotheres) at Colonies in the Tswapong Hills, Botswana

The endangered Cape Vulture (Gyps coprotheres), a southern African endemic, breeds on precipitous cliffs in various habitats. Some colonies of this cliff-nesting species are found in the southeast (Mannyelanong Hill) and east (Tswapong Hills and adjacent complexes) of Botswana. Of six breeding sites studied in the Tswapong Hills complex from 1992 to 1999, only two large colonies near the villages of Goo-Moremi (Bonwalenong site) and Goo-Tau (Manong Yeng site) and one small colony near Lerala (Kukubye site) still hold breeding vultures. In 2017 and 2018 we used direct observations to estimate the breeding population and breeding success of Cape Vultures at the Bonwalenong and Manong Yeng colonies, and we compared our findings with data from the 1990s. We identified 261 nests in 2017 and 362 nests in 2018, and monitored them throughout the breeding season. Breeding success at the two sites differed significantly between the 2 yr of our study (2017 and 2018). However, breeding success at Manong Yeng in 2017–2018 did not differ significantly from that documented in the earlier study (1992–1999). Our results also suggested relatively stable numbers of breeding pairs in the Tswapong Hills between 1992–1999 and 2017–2018. Cape Vultures in the Tswapong Hills require continued monitoring and research to better understand population dynamics and the key factors influencing breeding success and nestling survival.

Impacts of Great Cormorant and Cattle Egret Nesting on Other Waterbirds in a Shared Breeding Site in Piedmont (NW Italy)

Some waterbird species are believed to have an impact on other waterbird species as they are able to usurp a limited habitat and destroy vegetation. In this study, we have analysed the nesting dynamics of five waterbird species: Grey Heron Ardea cinerea, Great Cormorant Phalacrocorax carbo, Little Egret Egretta garzetta, Black-crowned Night Heron Nycticorax nycticorax and Cattle Egret Bubulcus ibis, that had settled in a colony in the Royal Castle Park of Racconigi (Cuneo, NW Italy) over a 17-year period (2000 to 2017). The Great Cormorant and the Cattle Egret settled in the colony in 2008 and 2012, respectively. We analysed the relationships between the number of breeding pairs of the five species. In addition, we used the time series forecasting method to study the nesting dynamics and the impact of the new settlements on the pre-existing colony. The number of nests of the Great Cormorant and the Cattle Egret increased annually, and these species significantly affected the nesting trends of the other pre-existing species: Grey Heron, Black-crowned Night Heron and Little Egret. The Grey Heron mainly suffered from the occupation of its old nests by the Great Cormorant from 2008 to 2013. However, since 2014, the Grey Heron has been able to react, by displacing its breeding site to the tops of trees adjacent to the old heronry, and this has resulted in an even greater number of nests than before 2008. The Black-crowned Night Heron and the Little Egret suffered more from the settlement of the new species than the Grey Heron did, and started to suddenly or gradually abandon the breeding site. The colony has been modified profoundly by the settlement of the Great Cormorant and the Cattle Egret, and it is still subject to dynamics that could transform it in the coming years.

Trialling camera traps to determine occupancy and breeding in burrowing seabirds

AbstractBurrowing seabirds are important in ecological and conservation terms. Many populations are in flux due to both negative and positive anthropogenic impacts, but their ecology makes measuring changes difficult. Reliably recording key metrics, the proportion of burrows with breeding pairs and the success of breeding attempts requires burrow‐level information on occupancy. We investigated the use of camera traps positioned at burrow entrances for determining the number of breeding pairs in a sample to inform population estimates, and for recording breeding success. The performance of two cameras makes we tested differed markedly, with Spypoint Force 10 trail cameras prone to malfunction while Reconyx HC600 Hyperfire cameras performed well. Nevertheless, both makes yielded season‐long activity patterns for individual burrows, eliminating uncertainty around successful fledging attempts. Dimensionality reduction of activity metrics derived from camera time series suggests breeding and non‐breeding burrows may be identifiable using linear discriminant analyses but sample sizes from our trial were low and group means were only significantly different during certain breeding stages (permutational multivariate analysis of variance: early chick‐rearing f = 3.64, P = 0.06; late chick‐rearing f = 8.28, P = 0.009). Compared with traditional techniques for determining burrow occupancy (e.g. manual burrow inspection and playback of conspecific calls at burrow entrances), camera traps can reduce uncertainty in estimated breeding success and potentially breeding status of burrows. Significant up‐front investment is required in terms of equipment and human resources but for long‐term studies, camera traps may deliver advantages, particularly when unanticipated novel observations and the potential for calibrating traditional methods with cameras are factored in.

Raptor reintroductions: Cost‐effective alternatives to captive breeding

AbstractReintroductions are becoming a popular tool to prevent extinctions, although their overall success rate is low. Assessing the efficiency and cost‐effectiveness of different reintroduction strategies may help identify and promote efficient practices. Captive‐breeding is widely used in animal reintroductions, although concerns have been raised about relatively high failure rates and economic costs. Here, we compared the effectiveness of two simultaneously used strategies in the reintroduction of the Bonelli’s eagle on the island of Mallorca: The release of captive‐bred chicks and wild‐reared, translocated non‐juveniles. To do so, we estimated the main vital rates for individuals released by both strategies and used these to perform population simulations to assess their overall performances. The use of wild‐reared non‐juveniles showed a trend with higher numbers of breeding pairs 10 years after the end of releases (14.75 pairs, 95% CI 4–25 vs. 11.21 pairs, 95% CI 2–24) and was the only strategy that prevented extinction in the long term. Following that, based on cost estimations of every strategy and different reintroduction budgets, we assessed the cost‐effectiveness of releasing wild‐reared non‐juveniles compared with two captive‐breeding alternatives: Releasing chicks either originally from breeding programmes or extracted from nests in natural populations. Again, releasing wild‐reared non‐juveniles was the only strategy that prevented long‐term extinction in all economic scenarios (i.e. low‐budget scenario 21.49 pairs, 95% CI 2–25). The use of chicks sourced from captive‐breeding programmes did not guarantee long‐term persistence even in high‐budget scenarios (14.50 pairs, 95% CI 0–25). Releasing wild‐reared non‐juveniles boosts early recruitment to the breeding population and early reproduction, which can be key for reintroduction success. However, in some scenarios, post‐release effects can be stronger in wild‐reared individuals, especially because of high translocation stress and post‐release dispersal. Hence, we recommend undertaking careful evaluation of the pros and cons of every strategy and embracing adaptive management to choose best strategies.

Population decline of the cape petrel (Daption capense) on King George Island, South Shetland Islands, Antarctica

The Antarctic and the surrounding Southern Ocean are currently subject to rapid environmental changes and increasing anthropogenic impacts. Seabird populations often reflect those changes and so act as indicators of environmental variability. Their population trends may provide information on a variety of environmental parameters on the scale of years or decades. We therefore provide long-term data on the cape petrel (Daption capense) population from a long-term monitoring program on Fildes Peninsula, South Shetland Islands, Maritime Antarctic, an area of considerable human activity. Our data, covering a period of 36 years, indicate some variability, but no clear trend in the number of breeding pairs between the breeding seasons 1985 and 2006. However, beginning in the 2008 season, the population decreased significantly and reached a minimum in the 2020 season. The mean annual decrease between 2008 and 2020 was 10.6%. We discuss possible causes of this strong negative population trend. Anthropogenic disturbance only affects a few breeding sites in the area and is therefore unable, on its own, to explain the consistent population decline at all the breeding sites studied. We think it more likely that reduced food availability was the main cause of the drastic decline in the cape petrel population.

Increasing wild boar density explains the decline of a Montagu’s harrier population on a protected coastal wetland

We studied the rapid decline in the number of breeding pairs (geometric growth rate λ = 0.86; 14 % annual decrease) of a semi–colonial ground–nesting bird of prey, the Montagu’s harrier (Circus pygargus), after twelve years of rapid population growth (λ = 1.15; 15 % rate of annual increase) in a protected coastal wetland in Eastern Spain. The study was conducted from 1992–2017, and the range of values in population size was: 2–37 breeding pairs. We contrasted 20 biologically–sound hypotheses (including local and regional factors) to explain the trend over time in the annual number of pairs. The most parsimonious model included a surrogate of wild boar (Sus scrofa) density in the region during the previous year and the annual number of Montagu’s harrier pairs breeding inland in the study province during the focal year. Syntopic western marsh harriers (C. aeruginosus) were not found to have any effect on the numbers of Montagu’s harriers either in our modelling or when we performed a quantitative and qualitative study both for years t and t–1. Our final ‘best’ models did not include spring rainfall, regional forest fires or local land use changes. The impact of wild boars on breeding success, together with conspecific attraction, could have resulted in the dispersal of coastal wetland birds to larger populations in dense inland shrub lands where levels of wild boar nest predation were more likely lower

Indicators keep progress honest: A call to track both the quantity and quality of protected areas

Indicators keep progress honest: A call to track both the quantity and quality of protected areas

Genetic diversity of the endangered Japanese golden eagle at neutral and functional loci

AbstractThe Japanese golden eagle (Aquila chrysaetos japonica) is an endangered subspecies with declining reproductive success. Previous research on this subspecies reported genetic diversity in northern Japan and in captivity using neutral genetic markers, but the situation in other areas of Japan and diversity at functional genetic loci are understudied. Here, we increased wild samples from western Japan and captive samples from zoos and analyzed genetic diversity of mitochondrial DNA, nuclear microsatellite loci, and the major histocompatibility complex (MHC) DRB exon 2 region. In addition, wild Scottish samples were analyzed and literature from European subspecies and other raptor species was surveyed to compare with the Japanese golden eagle. Overall, levels of mtDNA haplotype and microsatellite diversity observed in western Japan were similar to previously studied northern regions. However, microsatellite allelic diversity was lower compared to other golden eagle subspecies. MHC diversity indices, especially in captive Japanese golden eagles, were also low relative to raptors classified as Least Concern by the IUCN. This pattern could be explained by the loss of rare alleles due to genetic drift—a consequence of a declining population—suggesting the possibility of an early population bottleneck. Moreover, genetic structure analyses suggested that the Japanese population likely consists of one gene pool, so the bottleneck may affect the entire population. From these results, we suggest maintaining gene flow between local populations to prevent inbreeding and further loss of alleles, increasing the number of breeding pairs in captivity, and releasing captive individuals to reinforce the wild population.

Long-Term Population Fluctuations of a Burrowing Owl Population on Kirtland Air Force Base, New Mexico, USA

Western Burrowing Owls (Athene cunicularia hypugaea; hereafter, Burrowing Owls) were once widespread residents of grasslands throughout western North America, but their range has contracted, and abundance has declined in some regions. The causes of declines and geographic variation in population trends of Burrowing Owls are unclear but may be linked to changing land use and urbanization. Burrowing Owls are often found in association with airfields and airports, and their presence at such facilities is sometimes considered to be in conflict with those operations. Documenting the long-term persistence of Burrowing Owls at active airfields can help airfield managers who face decisions regarding compatibility of owls and airfield operations. We report the results of a long-term effort to monitor Burrowing Owls on Kirtland Air Force Base in New Mexico, USA, including the rapid recovery of Burrowing Owl numbers from near-extirpation and the relationships between abundance and other demographic traits. The number of breeding pairs of Burrowing Owls increased from one pair in 2013 to 28 pairs in 2019 and 2020, and the number of fledglings produced increased from one in 2013 to 84 in 2019 and 61 in 2020. The recovery was not uniform across all areas of Kirtland Air Force Base, and some formerly occupied areas remained unoccupied. We documented dispersal outside the Air Force base boundary and that the number of breeding pairs was more strongly influenced by the number of offspring produced in the prior year than the number of owls returning from prior years, which indicated that the population is part of a larger meta-population. Our results demonstrate that the maintenance of Burrowing Owl populations is not necessarily at odds with safe airfield operations, that Burrowing Owls exhibit complex population dynamics, and can rapidly recolonize previously occupied areas if habitat and nest sites remain suitable.

Phylogenomic Characterization of a Novel Corynebacterium Species Associated with Fatal Diphtheritic Stomatitis in Endangered Yellow-Eyed Penguins.

ABSTRACTYellow-eyed penguins, Megadyptes antipodes, are an endangered species that are endemic to New Zealand. Outbreaks of diphtheritic stomatitis have caused significant mortality for this species, especially among young chicks. In this study, we isolated 16 Corynebacterium sp. isolates from the oral cavities of 2- to 14-day-old chicks at a range of infection stages and sequenced the genomes to understand their virulence mechanisms. Phylogenomic and matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) characterization indicate that these strains belong to a novel Corynebacterium species. A simple multiplex PCR-based diagnostic assay has been developed to identify these strains rapidly and reliably. Similar to other corynebacteria, genomic islands and prophages introduced significant diversity among these strains that has potentially led to minor functional variations between the two lineages. Despite the presence of multiple corynebacterial virulence genes and a spaDEF-type pilus gene cluster among these strains, the survival rate was much higher in Galleria mellonella larvae than in those inoculated with Corynebacterium ulcerans NZRM 818 and Corynebacterium pseudotuberculosis NZRM 3004. Therefore, these strains are opportunistic pathogens causing high mortality among young penguin chicks due to a less-developed immune system.IMPORTANCE Yellow-eyed penguins, Megadyptes antipodes, are endangered species with a sharp decline in the numbers of breeding pairs over the last 2 decades. Diphtheritic stomatitis, characterized by a thick fibrinopurulent exudate in the oral cavities and symptoms, including inanition and significant weight loss, is responsible for significant mortality among the young chicks. These chicks are treated with antibiotics, amoxicillin-clavulanic acid or enrofloxacin, but do not always recover from the infection. The pathogen causing these infections and the mechanism of pathogenesis are unclear. This study has identified a novel Corynebacterium species to be associated with diphtheritic stomatitis in yellow-eyed penguins with potential virulence genes that are likely involved in pathogenesis. Importantly, a gene encoding an exotoxin, phospholipase D, is present among these strains. The inactivated form of this enzyme could potentially be used as an effective vaccine to protect these penguins from infection.

Effect of Nesting Substrate on the Breeding Performance of Peregrine Falcons in Guerrero Negro, Baja California Sur, Mexico, 2012–2016

The Peregrine Falcon (Falco peregrinus) breeds locally in the Guerrero Negro wetland complex, Baja California Sur, Mexico, but the most recent investigation of their breeding ecology in this wetland area was in 1998. Our objectives were to update the information on the reproduction of Peregrine Falcons in Guerrero Negro and to evaluate the relationship of reproductive parameters with the environmental temperature, rainfall, and nest substrate (natural or artificial). From 2012 to 2016 we surveyed for Peregrine Falcon nests, and monitored them from February to May each year. We recorded the type of nest substrate (natural or artificial) and the nest contents (eggs, nestlings, or fledglings) at every visit. Pooled across years, we recorded 34 reproductive events that produced 42 fledglings. On average per year, there were 6.8 ± 1.6 egg-laying pairs, and 4.4 ± 1.8 were successful, with a productivity of 1.23 ± 0.06 fledglings/egg-laying pair. Monthly mean air temperatures and rainfall had no effect on breeding parameters; however, there were significant relationships with type of nest substrates. On average, we found falcons had greater nesting success and productivity on artificial substrates (83 ± 15% and 1.91 ± 0.12 fledglings/egg-laying pair) than on natural substrates (36 ± 21% and 0.36 ± 0.21 fledglings/egg-laying pair). Compared to the 1998 estimate, the number of egg-laying pairs in Guerrero Negro has more than doubled (from four to nine); this wetland area currently holds the largest number of breeding pairs along the Baja California Peninsula.

The effect of Natura 2000 network on the Eurasian Eagle-owl (Bubo bubo) population in Southeast Bulgaria: implications for conservation

Abstract The effectiveness and efficiency of the Natura 2000 network for the Eurasian Eagle-owl conservation in SE Bulgaria was assessed by comparing data collected during a long-term study on number of breeding pairs and fledglings before and after network establishment. The Natura 2000 network and non-protected areas showed similar values of the calculated indices according to the number of occupied localities. However, the pairs in Natura 2000 sites bred significantly less fledglings after the creation of the network than the pairs in non-protected ones. The Special Protection Areas (SPA) system created specifically for the preservation of birds has the lowest efficiency in respect to Eurasian Eagle-owl protection. Proposals were made after ‘gap analysis’ for real protection and optimization of the protected-area network to increase the stability of the Eurasian Eagle-owl population in the changing environment.

Häckningsbiologiska studier av smålommar Gavia stellata på Holmöarna, Norra Sverige

The aim of this study was to estimate number of breeding pairs, breeding success, and distance to fishing areas in a population of the Red-throated Loon Gavia stellata on two of the main islands in the Holmöarna Archipelago in the northern part of the Baltic Sea, Sweden. Potential breeding waters were surveyed during seven years, 2010–2015 and 2019. Red-throated Loons appeared in 43 of the 135 lakes of sufficient size on the islands, and the population was estimated to 25–35 pairs, or about 2% of the Swedish population. The mean size of lakes with breeding pairs was 1.6 ha, and these lakes had an average of 82% water surface without vegetation (18% vegetation cover). The mean breeding success was low, 0.30 chicks per pair and year, and at least during one year, chicks were produced in only 20 (47%) of the surveyed lakes. The average distance between the nesting waters and the fishing areas for 17 studied pairs was 1.8 km. We discuss the characteristics of suitable nesting waters as well as the factors contributing to the low reproduction.

Coexistence without conflict, the recovery of Ireland\u2019s endangered wild grey partridge Perdix perdix

By 1995, Ireland’s wild grey partridge (Perdix perdix) was extinct nationally as a breeding species on farmland. The two populations remaining were confined to Ireland’s industrial cutaway peat bogs. One of these populations was deemed viable. In 1996, the National Parks and Wildlife Service of Ireland and the Irish Grey Partridge Conservation Trust established a conservation project to prevent the extirpation of this population. In this paper, we explore the impact of each management factor on two key demographic response variables: chick survival rates and the number of breeding pairs. The numbers of linear metres of nesting strips had the most significantly positive effect on spring pairs, followed by the total number of supplementary food hoppers and the total hectares of brood-rearing and over-winter cover. Counterintuitively, encounters with Hen Harriers (Circus cyaneus) did not negatively affect chick survival or the number of spring pairs. While we cannot rule out the contribution of each explanatory variable, none had a statistically significant effect on chick survival, suggesting there may be locally confounding factors that our model could not capture. The weather conditions during the peak hatching period had a significant influence on chick survival, with the average maximum temperature observed in June having the strongest positive association with an increase of 1 °C in the average maximum temperature in June associated with an increase in chick survival of 9.4% on average. Conversely, for every additional 1 mm of rain in June, there was a 0.23% drop in chick survival on average.

Long-Term Population Fluctuations of A Burrowing Owl Population On Kirtland Air Force Base, New Mexico, USA

Abstract Western Burrowing Owls (Athene cunicularia hypugaea; hereafter, Burrowing Owls) were once widespread residents of grasslands throughout western North America, but their range has contracted, and abundance has declined in some regions. The causes of declines and geographic variation in population trends of Burrowing Owls are unclear but may be linked to changing land use and urbanization. Burrowing Owls are often found in association with airfields and airports, and their presence at such facilities is sometimes considered to be in conflict with those operations. Documenting the long-term persistence of Burrowing Owls at active airfields can help airfield managers who face decisions regarding compatibility of owls and airfield operations. We report the results of a long-term effort to monitor Burrowing Owls on Kirtland Air Force Base in New Mexico, USA, including the rapid recovery of Burrowing Owl numbers from near-extirpation and the relationships between abundance and other demographic traits. The number of breeding pairs of Burrowing Owls increased from one pair in 2013 to 28 pairs in 2019 and 2020, and the number of fledglings produced increased from one in 2013 to 84 in 2019 and 61 in 2020. The recovery was not uniform across all areas of Kirtland Air Force Base, and some formerly occupied areas remained unoccupied. We documented dispersal outside the Air Force base boundary and that the number of breeding pairs was more strongly influenced by the number of offspring produced in the prior year than the number of owls returning from prior years, which indicated that the population is part of a larger meta-population. Our results demonstrate that the maintenance of Burrowing Owl populations is not necessarily at odds with safe airfield operations, that Burrowing Owls exhibit complex population dynamics, and can rapidly recolonize previously occupied areas if habitat and nest sites remain suitable.

Red-crested pochard, <em>Netta rufina</em>, breeding population in Piedmont (North Western Italy)

[The breeding of the Red-crested pochard in Piedmont is known since 2006, when it was first described in a pond near the town of Asti. Data were collected from specific databases and from field observations performed in 3 sites located in the Asti province and 2 sites in the Cuneo province, all of them placed along the Tanaro riversides. A further site is located in the province of Alessandria near the Po river along the border of Lombardy. On the whole, in the time span 2006-2019 the number of breeding pairs increased from 2 to a maximum of 7 per year. A total of 64 females with 326 chicks were recorded (average 5.1/female), June being the most favorable month for reproduction. Results point to the occurrence of a seemingly stable small breeding population. The lack of any kind of legal site protection, the anthropogenic disturbance (hunting, fishing, abandoning wastes), and the loss of the ideal habitat for reproduction are among the critical threats for the maintenance of a vital breeding population. There was a probable case of nest parasitism by Mallard duck, which is seldom observed since the opposite situation seems to be more common.]
 
 [Article in Italian]

Breeding biology of the Eleonora’s falcon, Falco eleonorae within the Galite archipelago

This study was carried out at Galite archipelago over two consecutive breeding seasons (2014 and 2015). We investigated the breeding ecology of Eleonora’s falcon population in Galite archipelago by providing detailed data on its breeding biology and assessing the nesting parameters. Overall, 127 Eleonora’s falcon breeding pairs were recorded in all six islets of the archipelago. The eastern part of the archipelago hosted the highest number of breeding pairs with the highest density recorded at Gallo island (5.93 pairs/ha). Eleonora’s falcon breeding pairs mainly used the protected crevices non-exposed to sun and wind. The overall mean clutch size (mean ± SE) was 1.78 ± 0.10 eggs per clutch. Clutches of two eggs and one egg were the most frequent at Gallo and Fauchelle, respectively. The average hatched eggs per clutch and fledglings per brood were 1.29 ± 0.10 and 1.24 ± 0.10, respectively. The brood size varied significantly with clutch size and nest exposition being higher related to not exposed nest and two as the clutch category was greater. Likewise, the number of fledglings significantly increased with increasing clutch category and was higher in not exposed nests. In fact, hatching or fledging probability increased significantly as nests were not exposed.

Heavy decline of the largest European Arctic Skua Stercorarius parasiticus colony: interacting effects of food shortage and predation

ABSTRACT Capsule The number of breeding pairs of Europe’s largest Arctic Skua Stercorarius parasiticus colony at Slettnes, Norway, showed a dramatic decline of at least 50% over two decades, with food shortage in four years and increasing predation by Red Fox Vulpes vulpes leading to total breeding failure in five out of six recent study years. Aims To document the decline of Europe’s largest Arctic Skua colony and quantify bottom-up and top-down effects on reproduction. Methods We compared nest counts between 1997–1998 and 2014–2019 and collected data on egg size, clutch size and nest success for all years, and adult body mass, nest attendance, at-sea activity, aggressive nest defence, Red Fox Vulpes vulpes encounters, daily nest survival and adult survival for 2014–2019. We deployed nest cameras to identify predators in 2018–2019. In addition, we developed a demographic model to estimate the fecundity required for a stable population. Results A higher proportion of time spent at sea, small eggs, low adult female body mass and indirect assessment of foraging fish availability suggested food shortages in four of six recent study years. At the same time, nest predation by Red Foxes, the likely predator involved, increased during the six-year study. The combined effects of food shortage and nest predation led to total breeding failures in 2017–2019. Conclusion We provide evidence of both bottom-up (food shortage) and top-down (predation) effects on reproductive investment and hatching success in this colony. The reproductive output in recent years is far too low to sustain a stable population. The severe decline of the Arctic Skua colony at Slettnes fits reported trends for this species across most of its European breeding range, as well as for its important host species, the Arctic Tern Sterna paradisaea and the Black-legged Kittiwake Rissa tridactyla.

Population status and trend of the threatened ivory gull Pagophila eburnea in Svalbard

The ivory gullPagophila eburneais a high-Arctic seabird associated with sea ice throughout the year. It breeds at high latitudes, mostly in the Atlantic sector of the Arctic. It is rare (<11500 breeding pairs globally) and remains one of the most poorly known seabirds in the world. Although Svalbard (Norway) supports breeding populations of international significance, the population trend in the region was unknown prior to this study. We conducted annual surveys of known breeding sites from 2006 to 2019 to estimate the size of the ivory gull population in Svalbard and to assess the population trend. We visited 117 colonies, 60 of which were new discoveries during this study. All breeding sites were situated in cliffs, and no ground-breeding ivory gulls were found. Based on the most complete survey in 2019, we estimated the Svalbard breeding population to be between 1500 and 2000 breeding pairs. We recorded an overall 40% decline in the number of breeding ivory gulls, but the trends varied significantly among colonies. The inter-annual fluctuations in the number of breeding pairs were not synchronous among colonies, which can be explained by the movements of adult breeding birds between colonies. The current decline in the Svalbard ivory gull population could be related to the ongoing decline in sea ice extent and quality in the Barents Sea. It may also be driven by ecological changes along the migration routes or at the wintering grounds, as hypothesized for the Canadian breeding population.

Формирование сообществ гнездящихся птиц парков Киева по градиенту антропического воздействия в мегаполисе

In settlements, safe places for birds nesting and feeding need to be created. The purpose of the work is to assess the state and identify vectors of the formation of nesting bird communities in parks under the pressure of anthropic load in the metropolis. In parks of Kyiv 62 species of birds nest. Such faunogenetic complexes like European nemoral (25.0–53.3%), Desert-mountain (12.0–27.8%) and Forest-steppe (6.9–25.0%) prevail. The number of community species in each of parks is 49–12, the average nesting density is 0.08±0.02–0.9±0.19 pairs / ha, and the dispersion is 0.12–1.62. With the combination of anthropic load on biotopes of more than 140 points with a small area of parks (2.0–16.5 ha), the species composition of communities decreases, and the average nesting density and density dispersion increase. Dominated by density: Parus major, Columba livia, Sturnus vulgaris, Turdus merula, Passer domesticus, Passer montanus, Fringilla coelebs, Columba palumbus, Apus apus, Ficedula albicollis, Erithacus rubecula, Turdus pilaris. All birds in communities are obligate synanthropes (12.9%; n=62) or hemisinanthropes. Obligate synanthropes are distributed in communities of 0-7 species. According to the gradient of increasing anthropic load on parks, logarithmic trends show a slight increase in the percentage share of obligate synanthropes in the species composition and in the number of breeding pairs. 47–70% nest on trees, 0–14.3% in shrubs, 0–13.0% on ground and in buildings. In parks, birds (16–38% of the species composition), in addition to using species-specific stations, nest in the cavities of buildings. Such species like Motacilla alba L., Sturnus vulgaris, Ficedula albicollis, Muscicapa striata Pallas, Erithacus rubecula, Parus major, Passer domesticus, Passer montanus nest in this way. Due to this nesting strategy, the need of the birds in hollows and the dependence on the woodpeckers in the community decreases. High parameters of the Shannon index (1.51–3.14) and Pielou index (0.61–0.95) were revealed, with low data of the Berger-Parker index (0.15–0.61). With an anthropic load of more than 160 points, there is a sharp decrease in species diversity, evenness of species, and increased dominance pressure. Cluster analysis showed the division of bird communities into similarity groups according to the area of the parks, the proximity of parks to the outskirts of the city and large forest tracts of the area and specifics of the anthropic load.