Long-term studies (1990-2008) of Dark-bellied Brent Geese Branta b. bernicla breeding on the Taimyr Peninsula in the Russian high Arctic, revealed a three-year cycle in breeding success linked to Siberian Lemming Lemmus sibiricus and Collared Lemming Dicrostonyx torquatus dynamics. Peak lemming years provide abundant prey for Snowy Owls Nyctea scandiaca, Arctic Foxes Vulpes lag opus and Pomarine Skuas Stercorariuspomarinus, whose interactions coincidently facilitate Brent Goose nesting. Snowy Owls defend their own territories against Arctic Foxes, and Pomarine Skuas do the same against both Arctic Foxes and Snowy Owls, severely restricting foxes and owls from preying upon Brent Geese, their nests and their goslings. Brent clutch size varied from an average of five eggs in Snowy Owl territories, to four eggs in gull Larus sp. colonies in peak lemming years, and three eggs in gull colonies in non-lemming years. Following lemming crashes (for reasons not understood), predator abundance remains high and Brent completely fail to breed or skip reproduction, as foxes and owls switch to alternative prey and skuas are absent from the area. In the third year, with predator decline (through starvation or emigration) and lemming recovery, Brent Goose nesting success improves. A year later, the three-year cycle starts again. The key role of skuas in limiting the owls' ability to catch and carry larger prey, such as geese, creates fox-free areas where Brent are able to nest successfully, confirming their previously overlooked role in the interspecific predator-prey interactions shaping Brent Goose reproductive success in the high Arctic. This review of papers and reports from the long-term studies describes how complex predator-prey and interspecific interactions determine the annual variation in breeding outcomes for Dark-bellied Brent Geese.
Understanding variation in survival and reproduction is key for conservation and management of bird populations. By compiling and analysing data on hatching success (i.e. proportion of nests with at least one hatched egg) from Common Eider Somateria m. mollissima, Velvet Scoter Melanitta fusca and Red-breasted Merganser Mergus serrator, all breeding on a single island in the Baltic Sea, we demonstrate that species-specific variation can be distinct even when nests are found in the same habitat on a relatively small study site. A total of 3,316 nests was found, and hatching success was determined for 2,890 nests during a four-year study period (2021-2024). Both Common Eider and Velvet Scoter exhibited considerable interannual variation in hatching success. Hatching success for Common Eider was highest in the two last years, but in the first two years for Velvet Scoter. Red-breasted Merganser showed more stable and generally higher hatching success than the other two species. Lack of covariation between species over the years indicates that species-specific traits such as phenology and behaviour (e.g. defence-mechanisms to avoid nest predation) may override other local factors influencing breeding success. Our results suggest that knowledge of annual variation in hatching success cannot be applied to other closely related species, even when those species are found breeding in the same area and habitat and may even share nesting sites.
The behavioural ecology of urban Greylag Geese Anser anser was reviewed in relation to selective forces or bottlenecks - such as habitat, food availability, predators, disturbance, hunting, diseases and parasites, nest sites and brood rearing areas, and competition with other species - which may act on geese in the contemporary European city environment. Special consideration was given to behavioural changes during winter and moult. Studies to date indicate that urban geese have developed survival and reproduction strategies which sometimes differ from those of geese in other habitats. For instance, they must adapt to a more built-up environment, as additional mortality may arise from collisions caused by flying within confined urban spaces. They are also exposed to urbanised native, introduced and "domestic" predators, such as dogs, to which they show size-related escape responses. Most urban geese adapt to human disturbances, adjusting the intensity of their behavioural response to the perceived danger. Like their rural counterparts, urban geese are also highly selective in their choice of food plants and feeding habitat, although supplementary feeding by people may induce a change in behaviour. There was no evidence that disease or parasite loads are higher for geese in urban than in rural areas. Urban Greylag Geese use a broader range of physical structures for nesting in urban than in rural areas, with some also adopting colonial nesting. Some families moved to new brood-rearing areas immediately post-hatching, elevating reproductive success. Competition with other species was evident at some sites, with Greylag Goose breeding success being inversely related to the local abundance of Egyptian Goose Alopochen aegyptiaca breeding pairs. Although wintry conditions with snow and ice cover may limit food availability and frozen lakes may hinder the ability of largely sedentary urban geese to escape from predators, they appear able to cope with prolonged periods of cold. Urban geese have also demonstrated resilience during their flightless wing moult period. It is unlikely that urban goose populations will grow indefinitely, as density-dependent processes will lead to a stabilisation of the numbers which occur within the boundaries of a given city, although the geese may disperse into surrounding rural areas.
Nest sitting by males is rare in the Anserinae subfamily and has never previously been reported for the Greater White-fronted Goose Anser albifrons. Here one case of a male repeatedly sitting on a nest is described, based on recordings from automatic camera traps used to study the behaviour of breeding pairs. The male attended the nest during the female's absence, and there was a positive correlation between the time that the female spent away from the nest and the duration of nest sitting by the male. The female's absent periods and the time spent nest sitting by the male both increased as incubation progressed but then decreased during the last five days before hatching. The female tended to leave the nest more frequently during the day, whereas the male's nest sitting was not affected by the time of day. Further studies with larger sample sizes are needed to ascertain how common nest sitting behaviour is in male Greater White-fronted Geese.
The geographically discrete Caucasus breeding population of the Velvet Scoter Melanitta fusca has shown significant range contraction to its one last existing colony in Georgia. Despite active conservation efforts at this site, where numbers currently appear to be stable, there is an evident need to understand past and present pressures that have driven the species to the verge of extinction in the region. An assessment of the potential for recreating suitable conditions for restoring the species to its former range and abundance is also required. Here, we review historical information to determine potential factors (some of which may still be in place) that contributed to the decline and range contraction of the Velvet Scoter in Armenia, Georgia and T & uuml;rkiye. Breeding surveys conducted in all three countries since 2013 confirmed the species' absence from all sites except for the breeding colony at Lake Tabatskuri in Georgia, which supported 45-50 pairs in 2024. Of 13 lakes with documented observations of Velvet Scoters, seven were confirmed as former breeding sites, with < 150 pairs in the last 60 years. The remainder were either spring/autumn staging areas, or unconfirmed breeding sites. For some sites, reasons for the loss of breeding Velvet Scoter locally were evident; for instance, at Lake Sevan in Armenia, reductions in the water levels in the lake rendered nesting islands accessible to terrestrial predators. Elsewhere, it was not possible to identify the causes of declines and extinctions, but by using the IUCN-CMP classification of threats and stresses we identified interactions with native species, recreational activity, hunting/egg collecting and fishing as critical threats to the viability of Velvet Scoters in the Caucasus. Several sites are suffering water quality issues, which require management interventions to restore turbid water to clear aquatic systems before the sites would become suitable for the return of the species. More site-based research and management will be necessary to restore the Velvet Scoter to its former levels of abundance and distribution.
