The Long-Term Monitoring of Bird Populations on Kolguev Island in the Barents Sea

Kolguev Island (69˚05′ N 49˚15′ E) is located in the Pechora Sea, the southeastern part of the Barents Sea. The island’s ecosystem is unusual due to the total absence of rodents and specialized predators such as weasels, while non-specialized predators such as Arctic (Vulpes lagopus) and red (V. vulpes) foxes and Rough-legged Hawk (Buteo lagopus) are common. Currently, 111 bird species have been registered here, of which 58 are nesting. The absence of rodents and the relatively stable predation pressure have resulted in the high abundance of many bird species: Willow Ptarmigan (Lagopus lagopus), several goose species, some waders, and passerines. Over the 125-year history of ornithological studies on Kolguev, the island avifauna has changed significantly. The trend of an increase in the proportion of widespread and Siberian species together with a decrease in the proportion of Arctic species was observed. Since 2006, a thorough monitoring of Kolguev avifauna has been carried out, during which the dynamics of the bird population densities have been traced. The abundance of Black-bellied Plover (Pluvialis squatarola) and Dunlin (Calidris alpina) decreased, while the numbers of Barnacle Goose (Branta leucopsis) have increased sharply since the 1980s. The breeding density of Rough-legged Hawk has also increased in recent years. The long-term monitoring of Kolguev ecosystems has indicated the high international conservation value of the island due to the high breeding density of many bird species. Our study, covering more than a century of avifaunal studies with almost annual monitoring over the past three decades, provides an unusually long and detailed time-series for an Arctic island.

Identifying drivers of spatio-temporal variation in survival in four blue tit populations

In a context of rapid climate change, the influence of large-scale and local climate on population demography is increasingly scrutinized, yet studies are usually focused on one population. Demographic parameters, including survival, can vary significantly across populations of a given species, depending on global or local climatic fluctuations but also on many other population-specific parameters such as breeding density, habitat naturalness, predation or parasitism. Such ecological differences between populations could lead to different paces-of-life (POL), whereby populations where reproductive investment is higher and behaviours are bolder display lower survival. We use here long-term (19 to 38 years) monitoring datasets from four Mediterranean populations of blue tits (Cyanistes caeruleus) to investigate the effects of sex, age class, large-scale and local climate temporal variation and population breeding density, on adult survival, using Capture-Mark-Recapture modelling. Environment heterogeneity in these four populations (two in evergreen and two in deciduous forests) has been linked to strong multi-trait phenotypic variation, suggesting blue tits in deciduous forests display faster POL compared to their conspecifics in evergreen habitats. The present results show heterogeneity in average survival probabilities across the four populations, with, as predicted, lower survival in the ‘fast’ blue tits occupying deciduous habitats. Interestingly, the year-to-year variation in survival probabilities was synchronous among populations. This suggests that regional environmental conditions could drive survival fluctuations across populations. However, breeding densities were not correlated across populations, and we found no evidence that adult survival is correlated with either large-scale or local, climate temporal variation in these four blue tit populations. Finally, two of the focal populations displayed a linear temporal decrease in adult survival over the study period. Overall, this multi-site study shows that blue tit parental survival from one spring to the next can vary substantially across years, in a synchronous way across populations, yet the climate indices we used are not correlated with the temporal variation. This calls for further investigations in other potential drivers such as resource (in particular insect) abundance, predation or parasitism.

Is earlier reproduction associated with higher or lower survival? Antagonistic results between individual and population scales in the blue tit

ABSTRACTAlthough it has been shown that phenology can respond to temporal environmental variation in free ranging populations of several species, little is known about the mechanisms of these responses and their effects on demography, and in particular on survival. Exploring phenological responses and their associated consequences on survival can be achieved at two distinct scales: the population scale, which focusses on a set of common responses to environmental conditions, and the individual scale, focusing on the relative position of each individual in the distribution of survival and phenology under particular conditions. In this study, we apply capture-mark-recapture multistate modelling on a 38-year monitoring dataset of blue tits (Cyanistes caeruleus) to investigate the effects of breeding phenology and some demographic covariates (breeding density, average and individual breeding success) on adult survival, at both population and individual scales. Our analysis revealed that (i) at the population scale, early breeding years are followed by lower average adult survival. (ii) At the individual level, earlier breeders within the population have higher subsequent survival than later breeders, although this relationship is reversed in years with very harsh conditions, e.g. warm spring and high breeding density. (iii) High individual relative breeding success is also associated with higher subsequent survival and explains more survival variation than relative phenology. Overall, our study indicates that, although earlier breeding is associated with a survival cost at the population level, substantial intrapopulation hererogeneity shapes a positive association between earlier breeding, breeding success and survival at the individual level.

Eurasian Pygmy-owl Glaucidium passerinum in Ukrainian Polissia

Background. The Eurasian Pygmy-owl Glaucidium passerinum (Linnaeus, 1758) is a rare and poorly studied species in Ukraine. It is listed in the Red Data book of Ukraine [2]. Its breeding locations can be found in the Carpathians, Roztochia and Polissia. There are insufficient data the on distribution and current state of abundance of Eurasian Pygmy-owl as well as breeding biology of the species on the territory of Polissia. Materials and Methods. The published data, internet sources, and unpublished materials of colleagues were used in addition to our own observations. Special studies were conducted on permanent study sites in Polissia Nature Reserve (Olevsk and Ovruch districts, Zhytomyr region) and Desniansko-Starohutskyi National Nature Park (Seredyno-Buda district, Sumy region). Small expeditions were organized to other locations within Polissia. Studies of this species were conducted in conjunction with the study of other owl species. They included surveys, behavioral observations, and eco­logy studies. During the surveys, the registrations on the routes of natural voca­lization of adult owls were made at twilight and at night; in cases when natural vocali­za­tion was absent, the recordings of mating calls of males and females were played [1]. The maximum distance of species registration by calling (500 m) was used for breeding density estimation. Results. During the breeding period, the Eurasian Pygmy-owl was found in all regions of Polissia. The southern boundary of that area lies near the villages Perebrody, Dubrovytsia district [12] – Karasyn, Sarny district [12] – Kochychyne, Yemilchyn district – Lypnyky, Luhyny district – Velyki Klishchi, Narodychi district – Stavrovka, Ivankiv district. The second site of regular breeding is the territory of Desniansko-Starohutskyi National Nature Park, where the species has been detected since 1996 [13]. For the first time, on the territory of Polissia, two nests in Zhytomyr and Sumy regions were found. For the first time in Ukraine, the clutch was measured. Behavioral observations of owls in breeding sites were conducted. Food remains were collected and identified. Conclusions. The Eurasian Pygmy-owl is a breeding species in Ukrainian Polissia. The average breeding density in Polissia is 5.8 pairs/100 sq. km. The permanent bree­ding range was identified; it covers the northeastern part of Rivne region, the northern part of Zhytomyr and Kyiv regions, the northeastern part of Chernihiv region and the northern part of Sumy region, on the area of 18.1 thousand sq. km. The estimated bree­ding population of this species is 330 pairs. During the mating season, there are two peaks of natural 24-hour vocalization activity: in the evening and morning twilight. In the evening, males often begin to call 30 min after sunset, in the morning – 30 min before sunrise. In the autumn-winter period, birds either stay within their breeding areas or migrate, flying outside the breeding habitats. The increase in the number of registrations is due to special surveys taking into account the narrow interval of 24-hour natural vocalization acti­vity in the twilight period and the use of phonogram reproduction techniques. Keywords: Eurasian Pygmy-owl, breeding, abundance, behavior, Polissia, Ukraine

Grassland bird species in mountain pastures Zaprikraj and Zapleč in the southern Julian Alps, Slovenia

Grassland birds were surveyed in two mountain pastures (Zaprikraj and Zapleč) in the southern part of the Julian Alps, Slovenia. The survey was carried out during the mornings between 26 and 30 June 2005. Due to the incomplete survey (only one visit, no nocturnal or targeted surveys and late season survey), the surveyed birds’ breeding density is only a rough estimate. 167 pairs belonging to 12 species were counted, with Tree (average density of 1.64 p/10 ha) and Water Pipit (average density of 1.60 p / 10 ha) being the most abundant. Both were observed in all altitudinal belts. The highest density in individual altitudinal belt was calculated for Red-backed Shrike Lanius collurio (3.78 p/10 ha) and Water Pipit (3.61 p/10 ha). In well preserved grasslands in the study area, most species reached high breeding densities compared to other parts of Slovenia and all were recorded higher than during the 1992 survey, although still mostly within limits of the elevations elsewhere in Slovenia. Breeding density of Skylark Alauda arvensis decreased with the elevation. Whinchat Saxicola rubetra, Skylark and Red-backed Shrike used significantly gentler slopes, while Pipits showed no preference for particular slopes.

Colony size affects breeding density, but not spatial distribution type, in a seabird

The spatial distribution of individuals within populations can result in fine-scale density dependence and affect the social environment that is encountered. As such, it is important to quantify within-population spatial structuring and understand the factors that shape it. In this study, we make use of point process statistics to test whether colony size affects the statistical type of spatial nest distribution produced by common terns (Sterna hirundo) breeding at identical manmade rectangular and homogeneous islands of fixed physical size. Comparing subcolonies of variable density both within and across years, we find that inter-nest distances are smaller at higher local and overall breeding density, but that the spatial distribution type does not vary across the observed densities. This suggests that the birds’ main settlement rules do not depend on density. In our case, analyses of fine-scale density dependence or potential social effects therefore do not need to account for between-individual heterogeneity in settlement decision rules or acceptance of these rules. We urge, however, other studies to similarly test for density dependence of the spatial distribution of individuals before undertaking such “downstream” analyses.