Apparent annual survival of staging ruffs during a period of population decline: insights from sex and site-use related differences

The ruff Philomachus pugnax, a lekkingshorebird wintering in Africa and breeding across northernEurasia, declined severely in its western range. Based on acapture-mark-resighting programme (2004–2011) in thewesternmost staging area in Friesland (the Netherlands),we investigated changes in apparent annual survival inrelation to age and sex to explore potential causes ofdecline. We also related temporal variation in apparentsurvival to environmental factors. We used the Capture-Mark-Recapture multievent statistical framework to overcomebiases in survival estimates after testing for hiddenheterogeneity of detection. This enabled the estimation ofthe probability to belong to high or low detectabilityclasses. Apparent survival varied between years but wasnot related to weather patterns along the flyway, or to floodlevels in the Sahel. Over time, a decline in apparent survivalis suggested. Due to a short data series and flag loss inthe last period this cannot be verified. Nevertheless, thepatterns in sex-specific detectability and survival lead tonew biological insights. Among highly detectable birds,supposedly most reliant on Friesland, males survived betterthan females (?/HDmales = 0.74, range 0.51–0.93;?/HDfemales = 0.51, range 0.24–0.81). Among lowdetectable birds, the pattern is reversed (?/LDmales = 0.64,range 0.37–0.89; ?/LDfemales = 0.73, range 0.48–0.93).Probably the staging population contains a mixture of sexspecificmigration strategies. A loss of staging femalescould greatly affect the dynamics of the western ruffpopulation. Further unravelling of these population processesrequires geographically extended demographicmonitoring and the use of tracking devices

Ornithological observations in Senegal

Ornithological observations in Senegal. We present observations made in Senegal in January 2015. Five sightings of rare species are described: a White-crested Tiger Heron Tigriornis leucolopha in the Saloum delta, a Shorteared Owl Asio flammeus in Madeleine Islands National Park, an Egyptian Nightjar Caprimulgus aegyptius in Djoudj National Park, a Shining-blue Kingfisher Alcedo quadribrachys in Niokolo-Koba National Park, and a Greater Hoopoe Lark Alaemon alaudipes in the Ndiael reserve. The predation of a Cattle Egret Bubulcus ibis by a Martial Eagle Polemaetus bellicosus, and the life history of a ringed Black-tailed Godwit Limosa limosa, are presented

Land‐use intensity impacts habitat selection of ground‐nesting farmland birds in The Netherlands

Agricultural intensification has modified grassland habitats, causing serious declines in farmland biodiversity including breeding birds. Until now, it has been difficult to objectively evaluate the link between agricultural land-use intensity and range requirements of wild populations at the landscape scale.In this study of Black-tailed Godwits Limosa limosa, we examined habitat selection and home range size during the breeding phase in relation to land-use intensity, at the scale of the entire Netherlands. From 2013 to 2019, 57 breeding godwits were tracked with solar-Platform Transmitter Terminals (26–216 locations [mean: 80] per bird per breeding phase) and used to estimate their core (50%) and home ranges (90%). Of these, 37 individuals were instrumented in Iberia and therefore unbiased toward eventual breeding locations. The tracks were used to analyse habitat selection by comparing the mean, median and standard deviation of land-use intensity of core and home ranges with matching iterated random samples of increasing radii, that is, 500 m (local), 5 km (neighbourhood), 50 km (region) and the whole of The Netherlands.Land-use intensities of the core and home ranges selected by godwits were similar to those at the local and neighbourhood scales but were significantly lower and less variable than those of the region and the entire country. Thus, at the landscape scale, godwits were selected for low-intensity agricultural land.The core range size of godwits increased with increasing land-use intensity, indicating high agricultural land-use intensity necessitating godwits to use larger areas.This is consistent with the idea that habitat quality declines with increasing land-use intensity. This study is novel as it examines nationwide habitat selection and space use of a farmland bird subspecies tracked independently of breeding locations. Dutch breeding godwits selected areas with lower land-use intensity than what was generally available. The majority of the Dutch agricultural grassland (94%) is managed at high land-use intensity, which heavily restricts the viability of breeding possibilities for ground-nesting birds. The remote sensing methodology described here illustrates the potential to study entire wild populations from the local field level to their whole spatial range

支子文庫本「拾玉集」について

Global climate change is rapidly altering the phenology and behaviour of species, leading to the occurrence of new and extreme trait values, especially among long-distance migratory birds. While infrequently published, the documentation and regular revision of the known spectrum of these trait values can be valuable for identifying the selective pressures acting on a population and influencing best management and conservation practices. Here we argue that the previouslydocumented spectrum of reproductive behaviours in the rapidly declining Continental Black-tailed Godwit Limosa limosa limosa is in need of revision. Our data show that new extreme values for a number of reproductive traits occurred during the 2014 breeding season and that by almost every metric, 2014 had the longest laying period on record for the population. These findings suggest that godwit reproductive biology may be more flexible than previously thought and that this flexibility should be reflected by changes in European meadowbird policies

Natal habitat and sex-specific survival rates result in a male-biased adult sex ratio

The adult sex ratio (ASR) is a crucial component of the ecological and evolutionary forces shaping the dynamics of a population. Although in many declining populations ASRs have been reported to be skewed, empirical studies exploring the demographic factors shaping ASRs are still rare. In this study of the socially monogamous and sexually dimorphic Black-tailed Godwit (Limosa limosa limosa), we aim to evaluate the sex ratio of chicks at hatch and the subsequent sex-specific survival differences occurring over 3 subsequent life stages. We found that, at hatch, the sex ratio did not deviate from parity. However, the survival of pre-fledged females was 15–30% lower than that of males and the sex bias in survival was higher in low-quality habitat. Additionally, survival of adult females was almost 5% lower than that of adult males. Because survival rates of males and females did not differ during other life-history stages, the ASR in the population was biased toward males. Because females are larger than males, food limitations during development or sex-specific differences in the duration of development may explain the lower survival of female chicks. Differences among adults are less obvious and suggest previously unknown sex-related selection pressures. Irrespective of the underlying causes, by reducing the available number of females in this socially monogamous species, a male-biased ASR is likely to contribute to the ongoing decline of the Dutch godwit population