Nest Density Research Articles

Ecological correlates of chimpanzee (Pan troglodytes schweinfurthii) density in Mahale Mountains National Park, Tanzania.

Understanding the ecological factors that drive animal density patterns in time and space is key to devising effective conservation strategies. In Tanzania, most chimpanzees (~75%) live outside national parks where human activities threaten their habitat's integrity and connectivity. Mahale Mountains National Park (MMNP), therefore, is a critical area for chimpanzees (Pan troglodytes schweinfurthii) in the region due to its location and protective status. Yet, despite its importance and long history of chimpanzee research (>50 years), a park-wide census of the species has never been conducted. The park is categorized as a savanna-woodland mosaic, interspersed with riparian forest, wooded grassland, and bamboo thicket. This heterogeneous landscape offers an excellent opportunity to assess the ecological characteristics associated with chimpanzee density, a topic still disputed, which could improve conservation plans that protect crucial chimpanzee habitat outside the park. We examined the influence of fine-scale vegetative characteristics and topographical features on chimpanzee nest density, modeling nest counts using hierarchical distance sampling. We counted 335 nests in forest and woodland habitats across 102 transects in 13 survey sites. Nests were disproportionately found more in or near evergreen forests, on steep slopes, and in feeding tree species. We calculated chimpanzee density in MMNP to be 0.23 ind/km2, although density varied substantially among sites (0.09-3.43 ind/km2). Density was associated with factors related to the availability of food and nesting trees, with topographic heterogeneity and the total basal area of feeding tree species identified as significant positive predictors. Species-rich habitats and floristic diversity likely play a principal role in shaping chimpanzee density within a predominately open landscape with low food abundance. Our results provide valuable baseline data for future monitoring efforts in MMNP and enhance our understanding of this endangered species' density and distribution across Tanzania.

Unexpected distribution of subordinates around nests of the wood ants

The hierarchical organization of multi-species ant communities can be determined by the colony size and worker density-dependent differences in behaviour, recruitment efficiency, and aggressiveness between colonies of different species. In this study, we compared the competitive effects of two territorial wood ant species, Formica rufa and F. polyctena, on the ant species subordinated to them (encounterers and submissives) that nest close-by their mounds. The nests of subordinates were mapped in 10 m2 plots around the mounds of each of the two wood ant species, situated at a distance of 10, 20 and 30 m in four directions. The most abundant subordinate species were two Myrmica species: M. rubra and M. ruginodis. Interestingly, the nests of subordinates had an even diversity, density and distribution along with the distance from the wood ant mounds. The wood ant presence had a species-specific negative effect on some of the subordinate species, which can be in relation with the smaller mound sizes in F. rufa compared to F. polyctena. Based on our results it seems that subordinate species, due to their adaptability, might tolerate the circumstances close-by the wood ant mounds by changes in their strategies, foraging behaviour, and switching to the use of alternative food sources, like corpses of wood ants present in high abundance. Although these might not allow reaching normal colony size and reproduction, they may allow the colonies to survive while maintaining relatively large nest densities.

Nesting tree selection by scattered heronry birds of drought prone Northern Bankura, West Bengal, India: preference of Phoenix sylvestris near wetland-associated habitats

The present study was conducted in the Gangajalghati block of Northern Bankura, India, to investigate the habitat and nest tree preference of three colonial waterbirds viz. Nycticorax nycticorax, Egretta garzetta, and Ardeola grayii. The study sites were surveyed for 20 months between 2017 and 2020. A total of 817 nests with an average of 204 per year were recorded on 13 tree species. Nycticorax nycticorax showed the maximum nest count followed by Egretta garzetta and Ardeola grayii. Relative abundance data revealed Phoenix sylvestris as the most abundant species (45%) of the area and harbours the highest proportion (33%) of nests. Pooled nest count data showed significantly higher (p < 0.01) total nest counts in the wetland associated habitats than others. The study observed more nest density of all three species near a cluster of small ponds than in a large water body. Year-wise difference in cumulative nest number and mean nest abundance of all three species was statistically insignificant. The interspecific nearest neighbour on Phoenix sylvestris were Egretta garzetta (88.37%) for Nycticorax nycticorax and Nycticorax nycticorax (83.25%) for Egretta garzetta and Ardeola grayii. Further, the study evaluated the impact of two tropical cyclones (Amphan and Fani) on the total nest count and found that more than 75% nests (p < 0.05) were destroyed by the mighty Amphan in May 2020. The study provides a baseline data on nesting trees and habitat preference of three species of heronry birds from Northern Bankura.

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.

Nest density and competing risks: A long-term investigation of Black Brant (Branta bernicla nigricans) nest survival

Many species of seabirds and waterfowl are predominantly colonial breeders, suggesting that colonial breeding is beneficial in some way. For Arctic nesting geese, colonial breeding may be an adaptive approach to minimize the risk of nest failure through predator swamping. Yet evidence for predator swamping is inconclusive. Species in low-lying coastal zones may have to manage tradeoffs between historical (e.g., predation) and increased frequency of other threats (e.g., coastal flooding associated with storm events). As the climate continues to change, coastal obligates will be subject to rising sea levels and an increase in extreme weather events, which could exacerbate the tradeoff between flooding and predation risk. We studied the effect of nest density on nest success in the colonial nesting Black Brant (Branta bernicla nigricans) on the Tutakoke River Colony in western Alaska and explored how density effects change during years of heavy Arctic fox (Alopex lagopus) predation and coastal flooding associated with storm events. We classified the colony as containing 2 strata that differed in elevation and vegetation, and were separated by the Tutakoke River. The stratum north of the Tutakoke River was 0.25 m lower in elevation and subject to periodic tidal flooding, while the southern stratum never flooded. Nest density positively affected brant nest success in years with high levels of fox predation. Nest success was greatest at the highest density during Normal years (low levels of fox predation and no flooding; northern stratum nest success 0.81 ± 0.01, southern stratum nest success 0.81 ± 0.01) and lowest in areas of low density during Fox years (northern stratum nest success 0.38 ± 0.01, southern stratum nest success 0.31 ± 0.01). Nest success was routinely higher during Normal years at all densities compared to Flood and Fox years. Our results support the hypothesis that colonial nesting, at least in tundra habitats, may have developed as a defense mechanism to swamp mammalian predators.

Density-dependence of nestling immune function and physiological condition in semi-precocial colonial bird: a cross-fostering experiment

BackgroundNesting in large aggregations provides several important advantages for colonially breeding birds. However, it also imposes certain costs, associated with facilitated pathogen transmission and social stress. The cost-benefit ratio is not similar for all the birds in a colony and it might be mediated by nest density. To investigate the influence of nest density on cell-mediated immune function and on physiological condition of nestlings, we arranged a cross-fostering experiment in three breeding colonies of black-headed gulls Chroicocephalus ridibundus. First, we exchanged eggs between plots of high and low nest density. Afterwards, we performed phytohaemagglutinin (PHA) skin test and we measured blood haemoglobin concentration in nearly 350 nestlings from experimental (exchanged) and control (non-exchanged) groups.ResultsWe found that PHA response was lowest in high nest density control group, indicating that depressed immune function of offspring, likely caused by social stress, can be considered as a cost of colonial breeding. Contrastingly, body condition of nestlings was the poorest in low density control group.ConclusionNestlings hatched and raised in high nest density plots did not have higher blood haemoglobin concentration in comparison to other study groups. Furthermore, they were affected with depressed cell mediated immune function, which is possibly driven by combined maternal (corticosteroid hormones deposited in yolk) and environmental (elevated social stress) effects. These results indicate that breeders from high nest densities do not benefit by rising offspring in better quality, in terms of immune function and body condition, although, in the light of previous studies, high nest densities are occupied by birds of higher individual quality, than low density areas. Our study provides a novel insight into the mechanisms of density-dependence that govern fitness of colonially nesting birds.

Ecology of Pheidole oxyops Forel, 1908, a dominant ant in neotropical savannas

Pheidole oxyops is a common and widely spread species in the central region of South America. Despite its ecological importance, relatively little is known about its habitat preferences, population dynamics and natural history. Here we provide information about the diet, daily foraging schedule, nest size and densities, and on the influence of habitat on the dynamics of P. oxyops colonies in southeastern Brazil. We found that P. oxyops is a habitat generalist, occurring in grasslands, savannas and forests. Although mean nest densities did not differ between the habitats we surveyed, the greatest densities were detected in the savanna plots, where up to 175 nests ha−1 were found. Pheidole oxyops presented an essentially predatory/scavenger habit, feeding on arthropod prey and especially on termites. Ant workers foraged during the day and the night at temperatures ranging from 14 to 28 °C. Nest mortality over a period of 1 year was positively related to initial nest densities, indicating a density-dependent regulation of the population. Nest growth rates were higher for small-sized—and thus presumably younger—nests than for large-sized nests. Overall, these life-history data reinforce the view that P. oxyops is a species typical of the Cerrado savannas, and a numerically and behaviourally dominant ant.

Bottom‐up effect of eradications: The unintended consequences for top‐order predators when eradicating invasive prey

Abstract The eradication of invasive species from islands yields significant conservation returns. However, novel challenges continue to arise as projects expand in their scope, complexity and scale. Prey‐loss and secondary poisoning were historically considered to have limited impact on native top‐order predators when planning eradications, but this has rarely been tested quantitatively. We used a 10‐year timeseries of Brown Skua Stercorarius antarcticus lonnbergi breeding surveys and isotopic dietary analysis on Macquarie Island to investigate how prey‐loss and secondary poisoning deaths resulting from the eradication of an abundant invasive prey species, European rabbits Oryctolagus cuniculus, affected a top‐order predator. Skua nest density declined from 7.14 nests/km2 (95% CI: 6.01–8.27) in the presence of rabbits (pre‐eradication) to 3.73 nests/km2 (95% CI: 2.96–4.51) in the first 3 years after the eradication of rabbits, before showing signs of recovery in the 4 years thereafter. However, breeding success dropped from 1.01 chicks/nest (95% CI: 0.76–1.26) to as low as 0.38 chicks/nest (95% CI: 0.23–0.53) with little evidence of recovery. Secondary poisoning affected a greater number of skuas than anticipated prior to the eradication, including skuas nesting in areas where rabbits were not typically hunted as prey. We highlight that invasive prey often replace native prey in the diet of native predators rather than provide an additional source of food, and rapid eradication of non‐native prey can have long‐term impacts for predators, particularly when recovery of native prey is slow. Synthesis and applications. Monitoring programmes that complement large‐scale eradication projects and address (a) trophic‐driven declines in predator populations and (b) population‐level impacts of secondary poisoning are integral to ensuring bottom‐up effects of eradications are anticipated and adequately quantified. If prey deficits caused by eradication of invasive prey are expected to be severe but short‐lived, supplementary feeding programmes may buffer against increased predation pressure on native prey and reduced breeding success of native predators. Alternatively, if the rapid recovery of native prey is not expected to occur naturally, breeding programmes and translocation of native prey prior to assist recovery of native predators should be considered to support ecosystem restoration.

Annual fluctuations in harvest mouse (Micromys minutus) nest densities in southern England.

Aerial nest surveys are the principal method of monitoring the distribution and habitat preferences of harvest mice (Micromys minutus), but monitoring has rarely been undertaken for more than three years at any site. Although nest surveys have inherent errors, they remain the most easily accessible and cheapest method. The aim of this study was to count the number of nests found in consecutive years at two sites in southern England. We found that the harvest mouse nest densities fluctuated over time. This supports other studies that indicate harvest mice populations undergo major fluctuations from year to year. Although the drivers of this annual variation in nest numbers have not yet been identified, surveying for harvest mice using aerial nest counts in just one year could underestimate their likely presence at that site.

Зв’язки чужорідних видів птахів з адвентивними рослинами насаджень парків і ботанічних садів

Introduction. In urban conditions, alien species of biota have become an integral part of the cultural landscape. Today, an overall assessment of the influence of alien species on the functioning of ecosystems of their secondary range as is relevant. Such an assessment requires knowledge of the connections formed by alien species in the secondary habitat. The purpose of the study was to find the connections of alien bird species with alien plant species in the parks and botanical gardens of Kyiv. Methods. Assessment was carried out in 10 forest parks, 3 botanical gardens, and 14 urban parks. In parks and botanical gardens, there is a wide range of plants alien to Kyiv Region, in contrast to forest parks. The number and distribution of birds were determined using the method of transect counts. The total area under study was about 370 hectares. Principal Component Analysis of the characteristics of habitats on which the number of alien birds may depend has been carried out. In the research, α-diversity indices of bird communities; number of people (individuals/km); number of pets (individuals/km); park’s area (ha); part of the territory; under the trees (%); part of alien species on plants communities (%) were analyzed. Results. Parus major, Turdus merula, Erithacus rubecula, Fringilla сoelebs dominate in all communities. Columba palumbus, Ficedula albicollis, Turdus pilaris, Columba livia, Apus apus, Sturnus vulgaris, Passer domesticus sometimes dominate in bird communities in parks and botanical gardens. There are no alien species in forest parks. 4 alien species nest in parks and botanical gardens: Streptopelia decaocto, Dendrocopos syriacus, Phoenicurus ochruros, Serinus serinus (from the last century). Phylloscopus trochiloides was observed for the first time. Nesting of Ph. trochiloides was not confirmed. Alien birds are not evenly distributed (0–3 species). Nest density is low: S. decaocto 0.013±0.01–0.021±0.01, D. syriacus 0.031±0.01–0.043±0.04, Ph. ochruros 0–0.034±0.02, S. serinus 0.013±0.01–0.017±0.01. We assume that alien bird species is an element that replaces the species that were eliminated from the community. Their nesting in forest parks is an indicator of a disruption of the functioning of the forest ecosystem as a result of anthropogenic transformation of the forest. The presence of alien species of birds in modern parks and botanical gardens is normal. Their biotopes were created on the sites of destroyed landscapes and with using alien plant species. Conclusion. In parks and botanical gardens, a specific structure of the plant community has developed due to the introduction of alien plant species, with a tree height of 3–5 m. As a consequence, alien birds find nesting stations in communities of nesting birds, which were not occupied by native species due to the absence of many species of tree canopy nesters and ground nesters birds. Alien species of birds also get access to vacant food resources. Alien birds use vacant resources. It was found that the area of parks has the most profound positive impact on the number of species of alien birds (+0.517), as well as the ratio of alien birds (+0.227). Other important correlations observed were the following: the number of species of alien birds in the bird communities – a part of alien species in plant communities (+0.084), the ratio of alien birds – part of alien species in plant communities (+0.041). The strongest negative connection is as follows: the number of species of alien birds in the bird communities – the number of pets (-0.213), the ratio of alien birds – the number of pets (-0.384).

THE INVESTIGATIONS OF THE NESTING STATUS OF THE GREEN TURTLE CHELONIA MYDAS ON YENIYURT BEACH (HATAY) IN THE NORTHEASTERN MEDITERRANEAN, TURKEY

A new nesting site that is not previously designated as a nesting beach was investigated for the green turtle (Chelonia mydas) nesting. The Yeniyurt Beach is bordered by BOTAŞ Port to the south and Secil Holiday Houses to the north. The small water channel in Yeniyurt Public Beach is taken to the reference point of which can be divided as the north, 2600 m long, and the south, 1400 m long. The beach was monitored between 15 June and 15 September in 2019. A total of 182 green turtle emergences occurred, and 85 (46.7%) of them were recorded as nests. The nest density was found as 21.2 clutches yr-1. The temporal distribution of the nests was found to be 52.9%, 45.8% and 1.3% in June, July and August, respectively. Besides, the average nest depth and incubation duration was 71.9cm ±8.2 (n=70) and 52.6 days ±4.4 (n=70), respectively. A total of 7362 eggs were laid in these nests and 6274 (85.2%) of them hatched. The average clutch size and number of empty eggshells were found to be 105.2 ±30.1 (40-199) and 89.6 ±26.4 (35-154), respectively. The average number of hatchlings reaching the sea was 62.8 ±20.8 (70.1%). Yeniyurt beach can be considered as a moderate dense beach (20−99 clutches yr-1; ≥6.5 clutches km-1 yr-1) for green turtle nesting based on previous studies in the Mediterranean.

Breeding Biology of the Lald (Fulica atra L.) at the Water Treatment Facilities of the Kharkov City.

Introduction.The anthropization of ecosystems is an important factor for the evolution of species and adaptation processes. Fulica atra L. is a fairly abundant species of wetlands in Ukraine. The adaptation of the coot to anthropogenic territories occurs during the winter period in cities, later birds remain in these areas for nesting.Purpose.To assess the current state of the coot population at water treatment facilities and Lake Novy Liman, which are the parts of the territory of the city of Kharkov. Studies of nesting biology of Fulica atra on Lake Novy Liman and silt sites of treatment facilities make it possible to assess the current state of the population of the species in the water bodies of Kharkov, as well as important for completeness assessments of the distribution of birds in wetlands.Methods. The studies were carried out in 2020-2021 during expedition trips to Lake Novy Liman and biological treatment facilities No 2 in Kharkov.Results.The nesting biology of the coot (Fulica atra L.) was investigated at the silt sites of water treatment facilities of the biological treatment complex No 2 in Kharkov and Lake Novy Liman in April-June 2020-2021. The reproduction biology of 73 pairs of coot was studied. To set the nesting density, a map with the coordinates of the nests has been created. The first eggs in clutches were found on average on April 16±1,4 at an average daily temperature of +5 ± 1,73 ̊Сat night and +20 ± 0,89 ̊Сduring the day in 2020 and on April 18±1,9 at +14,9 ± 3,08 ̊Сduring the day and +5 ± 2,76 ̊Сat night in 2021. Average clutch size 7,1 ± 1,13 eggs. First chicks: May 8-10. Average egg size (n = 223): 53,37 ± 2,56 x 37,05 ±1,45 mm. Vertebrates and birds of prey have been identified that can affect the breeding success of the coot.Originality.For the first time, a study of the breeding biology of the coot was carried out on the territory of treatment facilities and their surroundings.Conclusion.Wastewater treatment plants are an important place in the city of Kharkov, where birds undergo the process of adaptation to the anthropogenic landscape.Key words: coot, nestingbiology, egg laying, sewage treatment plants, Novy Lyman lake.

Distribution Pattern, Nest-Tree Features and Breeding Performance of Population of the Black Stork, Ciconia nigra (Ciconiiformes, Ciconiidae), in Northwestern Serbia

Distribution pattern, nest-tree characteristics and reproductive features of Black Stork’s population were evaluated in the floodplains of Gornje Podunavlje in Northwestern Serbia over five consecutive years. In total, 44 different nests were discovered and monitored. Nests were mostly placed on wide-diameter European Oaks and White Poplars between 5.5 and 18 m above ground level. Annually, the number of occupied nests varied between 26 and 16 with the declining trend over study years. The mean nesting density was 9.8 ± 2 occupied nests per 100 km2. Through study area, occupied nests were uniformly distributed and very isolated concerning the conspecific pairs. Predominantly, Black Stork preferred to nest on the lateral branches of the autochthonous mature trees with straight trunks and extensive crowns. These results suggest that the existence of old native forest stands represent crucial microhabitat criteria in the choice of the particular nesting site. In almost half of successful nesting cases, the most frequent number of fledglings was three. Overall productivity was relatively low with some variations between years implying poor nesting success.

Influence of the Cement Dust on Ants Grouping (Hymenoptera, Formicidae)

Research of the influence of cement dust in zone of PJSC “Ivano-Frankivskcement” on the ants grouping was conducted. In this exploration was noticed that at the anthropogenic load disappears ants of the genus Formica, which are replaced by species of the genus Lasius and Myrmica.
 Analyzing the distribution of ants genera and species on experimental meadows, we found a direct correlation between the ants number and distance from the sources of cement dust (r=0.87 at p<0.05). The largest number of the ant species observed in the area of influence from the genus Lasius. Myrmica nests are found not closer than 1 km from PJSC “Ivano-Frankivskcement”, Formica nests are only in the control. Under the action of cement dust on biotopes, the ants display a non-adaptive reaction. The analysis of changes in the population density of the particular genera showed that the nests density of all genera is minimal on the meadows located near the sources of cement dust. With remoteness from the source of pollution, the density of colonies reliably increases (r=0,97 at p<0,05). Colonies of the genus Formica (F. fusca) registered only in control reached the density of grouping 1,5±1,1 nests at 100m the accounting route. For the forest biotopes, the nests density of the genus Lasius is higher in control by 1.8 times (3.1 nests/25 m2) than in the village (1.75 nests/25 m2). For other genera (Camponotus, Myrmica and Formica), an opposite reaction was registered. The nests density of F. fusca, which are registered only in the control, reached 2.5 ± 1.1 nests for 100 m the accounting route.
 With a decrease in the pollution degree, the proportion of underground nests increases (r=0,90 at p<0,05), the proportion of the dome nests decreases (r=-0,94 at p<0,05). At the same time, the size of dome on average decreases when removed from the source pollution. All nests registered in the most polluted zone consist of a mixture of cement dust and earths up to 45 cm high. About 75 % of all nests found were heavily overgrown. When excavating the nests the dome was as if cemented.
 Adaptation of the ants to the influence of cement dust differs from other influence types and is expressed in the fact that in technogenic territories nests are more often dome-shaped, smaller diameter and considerably higher nests than those located in the control zone. This is because the soil near PJSC “Ivano-Frankivskcement” is covered with a layer of the lime dust which reaches 5 cm.
 Lasius niger is resistant to various forms of the anthropogenic influence, which can be explained by the adaptive features of the forms ant nest.

Птицы района озера Урдюжское и нижнего течения реки Сула (Малоземельская тундра)

В статье проанализированы результаты изучения распространения и численности птиц врайоне оз. Урдюжское и низовьях р. Сула в 1979, 1982, 1986 и 2018 гг. В ходе исследований зарегистрировано 98 видов птиц, принадлежащих к восьми отрядам: гагарообразные (2 вида), пластинчатоклювые (19), соколообразные (13), курообразные (4), журавлеобразные (1), ржанкообразные (27), дятлообразные (2), воробьинообразные (30). Из общего числа выявленных видов гнездятся 64, предположительно гнездятся 10, встречено на миграциях шесть, залетными являются пять, характер пребывания не выяснен для 14 видов птиц. В составе населения птиц района оз. Урдюжское за более чем 30-летний период (с 1986 по 2018 г.) выявлены заметные изменения. Вероятно, они связаны как с межгодовой динамикой видового разнообразия и численности, так с изменением фактора беспокойства в связи с прекращением промыслового лова рыбы в летний период, в результате чего значительно снизилась численность серых ворон, район стал местом крупной концентрации лебедей-кликунов на линьке, увеличилась плотность гнездования орланов-белохвостов. Исследования, проведенные в районе оз. Урдюжское, показали, что эта территория является важным местом обитания и линьки кликуна, ржанкообразных птиц, орлана-белохвоста и соответствует критериям водно-болотных угодий, принятых Рамсарской конвенцией.

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.

Nest-site selection of an avian urban exploiter, the Eurasian magpie Pica pica, across the urban-rural gradient

Although rapid growth in the extent of urbanized habitats across the globe represents a major threat to biodiversity, there is growing evidence that urban ecosystems can represent suitable habitats for many taxa, including birds. Exploring aspects of bird ecology across the urban-rural gradient, including determinants of habitat associations, are crucial to understanding responses to urbanisation. Here, we examined factors affecting nest-site selection of Eurasian magpies across an urban-rural gradient, contrasting urban and non-urban habitats. The presence and density of Eurasian magpie nests was positively associated with the proportion of green urban areas, and negatively with forests, arable land and buildings, despite habitat associations differing across the urban-rural gradient. We also found a negative relationship between nest height and distance from city edge. The highest nests were found in city centre residential areas, whereas the lowest nests were in the new residential areas. We conclude that Eurasian magpies can successfully exploit urban environments, partially due to adaptation of their nesting behaviour. In particular, they construct their nests higher in urban areas to avoid the negative impacts of human disturbance and predation.

Habitat features and colony characteristics influencing ant personality and its fitness consequences.

Several factors can influence individual and group behavioral variation that can have important fitness consequences. In this study, we tested how two habitat types (seminatural meadows and meadows invaded by Solidago plants) and factors like colony and worker size and nest density influence behavioral (activity, meanderness, exploration, aggression, and nest displacement) variation on different levels of the social organization of Myrmica rubra ants and how these might affect the colony productivity. We assumed that the factors within the two habitat types exert different selective pressures on individual and colony behavioral variation that affects colony productivity. Our results showed individual-/colony-specific expression of both mean and residual behavioral variation of the studied behavioral traits. Although habitat type did not have any direct effect, habitat-dependent factors, like colony size and nest density influenced the individual mean and residual variation of several traits. We also found personality at the individual-level and at the colony level. Exploration positively influenced the total- and worker production in both habitats. Worker aggression influenced all the productivity parameters in seminatural meadows, whereas activity had a positive effect on the worker and total production in invaded meadows. Our results suggest that habitat type, through its environmental characteristics, can affect different behavioral traits both at the individual and colony level and that those with the strongest effect on colony productivity primarily shape the personality of individuals. Our results highlight the need for complex environmental manipulations to fully understand the effects shaping behavior and reproduction in colony-living species.

Ecological Population Status of the Most Common Bird Species in Northern Altai Low-Mountain Forests and the Principal Difference in Avifauna Status in Altai and Baikal Regions

In 2016 and 2017, from April to July, bird individual nesting home ranges were regularly mapped along the permanent census route (2.8 km) in the low-mountain forests dominated by pine and birch. For each bird species, the nesting densities and average sizes of the bird individual nesting home range were estimated, and raster maps of spatial allocation (MSA) at the scale of the raster grid of 50 × 50 m were obtained. The degree of spatial conservatism (DSC) for each local population was inferred from the pairwise comparisons of the specific MSAs obtained at the same area (28 ha) in different years with the use of the Gamma rank correlation method. The statistical dependence of the population habitat area on DSC was demonstrated earlier (Cherenkov, 2017). The more habitat area is found within the trial plot, the less dependent (random) the individual spatial allocation within a population is observed in different years. Significant DSC estimates (p < 0.05) were obtained for 15 species, and their habitat areas and habitat saturation were found. The population status was inferred from the degree of habitat saturation. Average estimates of the degree of habitat saturation were close in migratory and nonmigratory species (49 and 45%, respectively). The Altai migratory birds wintering in Southeast Asia did not differ statistically in the degree of habitat saturation from those wintering in Southern Europe and North Africa. A comparison of avifauna status of the Altai and Baikal regions revealed substantial differences. In Altai the number of the most common migratory nesting species is almost twice as high, their average nesting density is four times higher, and habitat saturation is twice as high as in the birds of the Baikal region. The interregional differences in the degree of habitat saturation indicate that most of populations of the migratory species of the Baikal region are subject to twice as much intensive pressure of some factors limiting the population growth compared to the Altai populations. At the same time, there were no significant differences in the ecological population status of the nonmigratory species between these regions. Close estimates of the degree of habitat saturation in nonmigratory species in the Altai and Baikal regions support a suggestion that the integrate influence of factors limiting their population numbers is similar in both regions. Close estimates of the degree of habitat saturation and nesting density in the migratory and nonmigratory Altai species show that neither of the two strategies of surviving gives a pronounced advantage. The difference between the Altai and Baikal regions in the degree of habitat saturation in the migratory species is seemingly determined by the different mortality levels in the wintering areas and on the routes of migrations.

What can the abundance of Grey Parrots on Príncipe Island tell us about large parrot conservation?

AbstractWhile populations of the Endangered Grey Parrot Psittacus erithacus have collapsed across its range, the species remains remarkably abundant on the island of Príncipe, Gulf of Guinea. We examine how aspects of its ecology interplay with local environmental conditions, to inform conservation strategies for this species and other large parrots. On Príncipe, parrots breed in large trees of common species, with nest densities (42 ± 34 km−2) greatly exceeding those for any comparably sized parrot. Productivity is high (1.9 chicks per cavity), probably reflecting the absence of nest competitors and predators. Food sources are abundant and much of the island is inaccessible to trappers, so many nests are successful each year. Historically harvest has involved taking only chicks from trees in a few traditional patches. These conditions have combined to allow Grey Parrots to thrive on Príncipe, while elsewhere nest trees are timber targets, nest competition and nest predation are likely to be more intense, trapping is indiscriminate, and few areas remain unexploited by trappers. Preservation of large trees as breeding refugia, and vigilance against the indiscriminate trapping of adult birds, are identified as key conditions to stabilize and recover mainland Grey Parrot populations and indeed large parrots generally, given their very similar ecological traits and anthropogenic circumstances.