Crag Martin neontology complements taphonomy at the Gorham's Cave Complex

Species present in the fossil record may continue to exist at an archaeological site, allowing study that fine-tunes our picture of the ecological past. A large wintering population of Eurasian Crag Martins Ptyonoprogne rupestris (ECM) roosts at the ‘Gorham’s Cave Complex’ UNESCO World Heritage site in Gibraltar, which is best known for its occupation by Neanderthals at times when ECMs were also present. Its complex geomorphology allows the study of use of different micro-sites (caves) within the roost. We used mark-recapture to test whether birds showed fidelity to micro-sites for roosting, and for differences in condition of birds across micro-sites. ECM showed very high fidelity towards micro-sites, within and between years, with > 90% chance of recapture at caves where they were first caught. Condition of birds differed between micro-sites, suggesting differences in roost quality between caves; birds were more likely to be recaptured at the micro-site where birds were in best condition, indicating higher survivorship. Our results demonstrate extremely fine-scale fidelity at the largest roosting site documented for ECM globally. Implications for conservation are discussed. The study provides current knowledge of a bird that has been using these caves since the Pleistocene and more generally on these caves as refuges.

Rapid growth of the Bar-headed Goose Anser indicus wintering population in Tibet, China: 1991–2017

Summary Four of China’s six wintering populations of “grey” geese Anser spp. declined during the last decade. In contrast, the Bar-headed Goose A. indicus wintering population in China’s Tibet Autonomous Region more than doubled. During six surveys in Tibet over a 27-year period (1991/92 to 2017/18 winters) we documented an annual growth rate of 6.8% in the Bar-headed Goose population – an increase from approximately 10,100 to 68,100 birds. We propose that in addition to the cessation of hunting, the population growth of Bar-headed Goose is being driven by changes in agricultural land use patterns in Tibet, the establishment of protected areas on the wintering and breeding grounds, and the impacts of climate change across the Tibetan Plateau. Consistent with this hypothesis, the sown area of winter wheat in Tibet has increased and geese have shifted from primarily feeding in crop stubble to planted winter wheat fields. We also found that the most rapid population growth coincided with a 1998 climate regime shift across the Tibetan Plateau resulting in warmer temperatures, an increase in net precipitation, the appearance of new lakes and changes in the water levels and surface area of historical lakes. We suggest that warmer temperatures and high-quality forage on the south-central Tibet wintering grounds may be enhancing over-winter survival, while on the breeding grounds the expansion of lakes and wet meadows is augmenting breeding and brood-rearing habitat.

Primera localización de un dormidero de milano real Milvus milvus L., 1758 en un eucaliptal en Álava

During the 2020-2021 census to determine the wintering population of Red kite (Milvus milvus) in the Iberian peninsula by counting the number of communal roosts, one such roost was observed in a small reforested area of eucalyptus (genus Eucalyptus) in the northwest of the province of Álava (Basque Country-Spain). Although roosts located on this kind of arboreal substrate are rare, our observation suggests the hypothesis that Red kites will use eucalyptus if the atmospheric conditions are particularly adverse. Therefore, we propose that the distribution and winter ecology of Iberian breeding populations of Red kite be clarified with urgency, the study of which is hampered by the arrival of a multitude of conspecifics of central and northern-European origin in winter

Wintering shorebird in sandy coasts of Catania’s gulf (Sicily, Italy): 2011-2020

Sandy coasts are specific habitats of high ecological significance for many species of shorebirds. The Gulf of Catania, in the Eastern coast of Sicily, is considered one of the most important sandy coastal areas of the region for the wintering of different species of Charadriidae and Scolopacidae, also due to the presence of River Simeto’s mouth and other freshwater streams. Since the area has been subject to many changes in the last few decades and recent data were not available, a ten-year monitoring of the wintering shorebird community has been carried out, from January 2011 to January 2020, to understand its current ecological role and to update the knowledge about numbers and trends of Sicilian wintering shorebirds along the coast. A total of 3,171 individuals and 16 different species were observed, including a considerable amount of individuals of Calidris alba and Charadrius alexandrinus, despite the latter showed an 80% decrease in number in the last 20 years in the area. For each species, maximum numbers observed per winter and related five-year averages, estimates, IKA (Index of Abundance per Kilometre) and percentages in relation to the national wintering population have been reported. Furthermore, data about species associations were collected and analysed. This survey shows how the ecological value of River Simeto’s mouth has decreased considerably in the last decades in favour of other locations, such as the mouth of Canale Arci, where almost 50% of the birds were observed.

Decline of White-throated Bushchat Saxicola insignis Gray J.E. & J.R. Gray, 1847 (Aves: Passeriformes: Muscicapidae) in Nepal: implications on its global status

The White-throated Bushchat, also known as Hodgson’s Bushchat, is a long-distance migratory and specialist grassland bird categorized as Vulnerable on the IUCN Red List. In Nepal, White-throated Bushchat winters in the lowlands, and has been primarily recorded in large Phantas (=open plains of grassland). We present the population status of the species in Shukla Phanta, the largest continuous lowland grassland in Nepal that is known to hold the largest wintering population of White-throated Bushchat in the Indian subcontinent. Our 2013–2014, 2016–2017, and 2017–2018 winter surveys for White-throated Bushchat followed the same method used in the 1997–1998 and 2007 surveys in Shukla Phanta for comparable assessment of the status of the species. Our study provided overwhelming evidence that the species has undergone a steep decline over the last two decades (probability of 92% for a decline greater than 5% per year). Shukla Phanta is dominated by the species’ preferred habitat of Imperata cylindrica, Narenga porphyrocoma, and Saccharum bengalensis. Grassland patches managed through controlled burning leaving enough reeds for perches, grazed at medium level of intensity by wildlife and within close distance to water were found to support higher numbers of White-throated Bushchat. Given the observed steep decline in the largest known wintering population of the species and similar declines observed in the wintering populations in India, its status warrants uplisting to Critically Endangered, and we recommend an urgent review of its global status.

First successful breeding of Osprey Pandion haliaetus in Sardinia since 1968

In 2020, a pair of ospreys nested in the north western coast of Sardinia and the successful fledging of two chicks is the first record in the island since 1968. The last reported breeding occurred in the eastern coast of the island and after that the species was considered extinct. Ospreys regularly migrate, estivate and winter in Sardinia, with a wintering population of about 40 individuals in 2018. This new breeding episode is not resulting from reintroduction projects and may be related to the dynamics of the close population of Corsica and to the exceptional absence of human disturbance along the coast due to COVID 19 lock-down.

Winter movement patterns of a globally endangered avian scavenger in south-western Europe

Partial migration, whereby some individuals migrate and some do not, is relatively common and widespread among animals. Switching between migration tactics (from migratory to resident or vice versa) occurs at individual and population levels. Here, we describe for the first time the movement ecology of the largest wintering population of Egyptian Vultures (Neophron percnopterus) in south-west Europe. We combined field surveys and GPS tracking data from December to February during four wintering seasons (2014–2018). The wintering population consisted on average of 85 individuals (range 58–121; 76% adults and 24% subadults). Individuals were counted at five different roosting sites located near farms, unauthorized carcass deposition sites and authorized carcass deposition sites. Our results show that vultures tend to remain close to the roosting site. Moreover, we observed that females exhibited smaller home range sizes than males, which suggests a possible differential use of food sources. Overall, birds relied more on farms than other available food resources, particularly subadult individuals which exploited more intensively these sites. Our results showed that Egyptian Vultures congregate in significant numbers at specific sites throughout the winter period in south-west Spain and that these roosting and feeding sites should be given some level of legal protection and regular monitoring. Furthermore, predictable food sources might be driving the apparent increase in the non-migratory population of Egyptian Vultures, as observed in other avian species which are also changing their migratory behavior.