Michael J. McGrady

MIGRATION AND RANGING OF PEREGRINE FALCONS WINTERING ON THE GULF OF MEXICO COAST, TAMAULIPAS, MEXICO

Abstract Movements of 11 female and 1 male adult Peregrine Falcons (Falco peregrinus) wintering in coastal Gulf of Mexico, Tamaulipas, Mexico, were monitored with satellite-received transmitters (PTTs), 1997–1998. Median areas for minimum convex polygon winter home ranges at 50% and 90% levels (both years) were 1173 and 8311 ha, respectively. Most birds left wintering grounds in the first week of May. Duration of northward migration averaged 30 days. Distances between capture location and summer settling place were between 4580 and 5844 km; birds traversed 40.4–46.4 degrees of latitude. Birds summered between far western Canada and coastal west Greenland. One was followed to the same summering ground in both years. Autumnal migration routes were through the middle of the continent, and initiated in August and September. Falcons arrived on wintering grounds in September and October, averaging 40 days to make the journey. PTT data and capture locations of birds trapped in more than 1 year suggest fidelity to wintering areas, although perhaps not particular winter home ranges. Migración y Áreas de Ocurrencia de Halcones Peregrinos Invernantes en la Costa del Golfo de México, Tamaulipas, México Resumen. Entre 1997 y 1998, se monitorearon con transmisores de satellite (PTTs) los movimientos de 12 halcones peregrinos adultos (Falco peregrinus; 11 hembras y 1 macho) invernando en la costa del Golfo de México, Tamaulipas, México. Se utilizaron niveles de precisión del 50% y 90% en los polígonos mínimos estimados para describir los hambitos hogareños de invernada (en ambos años); éstos fueron de 1173 y 8311 ha, respectivamente. La mayoría de las aves abandonaron las areas de invernada en la primera semana de mayo. La duración de la migración hacia el Norte promedió 30 días. Las distancias entre los lugares donde las aves fueron capturadas y donde se establecieron en el verano variaron entre 4580 y 5844 km; así que éstas recorrieron entre 40.4 y 46.4 grados de latitud. Los halcones pasaron el verano entre el lejano oeste de Canadá y la costa oeste de Groenlandia. Uno de ellos fue seguido en ambos años hasta la misma área de veraneo. Las rutas migratorias del otoño tuvieron lugar a través del centro del continente y se iniciaron en agosto y septiembre. Los halcones peregrinos llegaron a las áreas de inviernada en septiembre y octubre, promediando 40 días para hacer el recorrido. Los datos de los PTTs e información sobre las ubicaciones de los lugares de captura de las aves atrapadas en más de un año sugieren fidelidad a las áreas de invierno, pero tal vez no a hambitos hogareños particulares.

Ranging distance of resident Golden Eagles Aquila chrysaetos in western Scotland according to season and breeding status

Capsule Home-range of resident pairs of Golden Eagle was usually smaller during a successful breeding season than during winter and during an unsuccessful breeding season. Aims To examine how Golden Eagles use space around their nests with respect to season and breeding status, and to compare home-range-use between a high and a low density region. Methods Nine adults in six mainland Argyll ranges were radiotracked between 1991 and 1996. On the island of Mull visual observations of range-use were obtained for five ranges between 1994 and 1998. Results Overall, Mull ranges were smaller than the Argyll ranges, reflecting the much higher range density on Mull. In both regions there were significant differences between ranging distances with season and breeding status. In general, ranging distances were smallest during breeding seasons when young were fledged. Conclusions Studies of range-use in Golden Eagles must be conducted across a 12-month period, as a minimum.

Using satellite telemetry and environmental niche modelling to inform conservation targets for a long-distance migratory raptor in its wintering grounds

We thank to the Natural Research Ltd for funding. R. Liminana benefited from a postdoctoral grant (reference 10/12-C) co-funded by ‘Consejeria de Educacion y Ciencia’ and the European Social Fund.

Movements and habitat use by immature Cinereous Vultures (Aegypius monachus) from the Caucasus

Capsule Juvenile and immature Cinereous Vultures from the Caucasus move large distances across undeveloped open-dry habitats in response to snowfall or high summer temperatures. Aim To study local and long-range movements of Cinereous Vulture (Aegypius monachus), and investigate the influence of environmental variables on spatial and temporal distributions of the species on a large scale. Methods We use 4-year-long location data from 6 juvenile Cinereous Vultures fitted with satellite-received transmitters to track their movements and obtain habitat suitability models. Results A few months after fledging, Cinereous Vultures may migrate from the Caucasus as far south as the Arabian Peninsula. Their movements are concentrated in undeveloped open-dry habitats. High temperatures push the vultures to higher latitudes and altitudes, while reverse seasonal movements are triggered by the extent of snow cover. Conclusions Our study shows the importance of the Arabian Peninsula and Iran as wintering areas for Cinereous Vultures. Long-distance movements by immature cinereous vultures are determined by climate seasonality, and in light of climate-warming scenarios for the next 100 years, there might be a shift in timing of the onset of the species seasonal movements and a change in the duration and geography of its wintering and summering.

Unusual clockwise loop migration lengthens travel distances and increases potential risks for a central Asian, long distance, trans-equatorial migrant, the Red-footed Falcon Falco vespertinus

ABSTRACT Capsule: Red-footed Falcons Falco vespertinus migrating from northern Kazakhstan proceed west before heading south to Africa; their northbound travel follows a different route with passage close to shooting hotspots in the Mediterranean. Aim: To use tracking and ringing data to document for the first time the migration of globally threatened Red-footed Falcons from northern Kazakhstan. Methods: Light-level geolocators were deployed on breeding adults in Kazakhstan and recovered one year later. Ringing and observational data from more than 100 years of Russian-language and other literature were summarized and mapped alongside the geolocator data. Results: Geolocator, ringing and observational data together demonstrate that Red-footed Falcons from northern Kazakhstan have a clockwise loop migration that begins with a long and unusual westward trek around eastern Europe’s large inland seas before continuing to extreme southern Africa. Return migration is farther west and requires crossing two major migratory barriers: the Sahara and the Mediterranean. Conclusion: The loop migration we describe requires an extensive longitudinal movement, exposes central Asian Red-footed Falcons to multiple desert, mountain and marine crossings, and, at outbound and return Mediterranean bottlenecks, crosses sites where raptor shooting is common.

Dispersal: a matter of scale

Population density around the natal site is often invoked as an explanation for variation in dispersal distance, with the expectation that competition for limiting resources, coupled with increased intra-specific aggression at high densities, should drive changes in dispersal distances. However, tests of the density-dependent dispersal hypothesis in long-lived vertebrates have yielded mixed results. Furthermore, conclusions from dispersal studies may depend on the spatial and temporal scales at which density and dispersal patterns are examined, yet multi-scale studies of dispersal are rare. Here, we present the findings of a long-term study examining factors influencing natal dispersal distances for the non-migratory population of Peregrine Falcons (Falco peregrinus) in the British Isles across distinct spatial and temporal scales. Our smallest scale study included Peregrines ringed as nestlings and subsequently recaptured alive in south Scotland-north England, an area that was intensively studied during the time periods 1974-1982 and 2002-2016. Second, we examined dispersal patterns of birds ringed as nestlings in south Scotland-north England, but subsequently recaptured alive or recovered dead anywhere in the British Isles. Finally, we examined the natal dispersal patterns for Peregrines ringed and recaptured or recovered anywhere in the British Isles from 1964 to 2016. Consistent with prior findings, females dispersed farther than males across all scales. However, the patterns of dispersal were strongly scale dependent. Specifically, we found a lack of a discernible relationship between index of density and dispersal distance in the limited study area, but when region-wide recaptures and recoveries were included in the analyses, a negative relationship was revealed. Our results suggest that conclusions of dispersal studies may be scale dependent, highlighting the importance of spatial and temporal scales in examining and interpreting the relationship between population density and dispersal patterns.

Seasonal change in habitat use in Steller's sea eagles

Habitat-use by Stellers sea eagle Haliaeetus pelagicus , categorized as Vulnerable on the 2002 IUCN Red List, was studied using satellite-tracking. This migratory species breeds in eastern Russia and mostly overwinters in Hokkaido, Japan, and the southern Kuzil islands. Locations of eagles were classified as being river, sea, lake, or other habitat. In autumn, eagles mainly used river habitats, probably because of the availability of abundant post-spawn dead salmon. In winter about one third of eagles continued to be located on rivers, with others on sea coasts and lake sides. During the spring migration and breeding season habitat use by adult eagles probably reflected the variety of habitats in which breeding occurs. At that time, sub-adult eagles were located mainly on the sea coast, probably in places where food supply was sufficient and there were few territorial eagles. In Hokkaido 35% of overwintering eagles used mountain areas for at least some time. It is known that eagles using mountain areas in Japan in winter scavenge upon the carcasses of sika deer Cervus nippon killed by hunters, and are thus exposed to possible lead poisoning. The satellite tracking highlights the importance of several habitats within the range of this species, changes in which could affect its conservation status.

First case of the Steller’s Sea Eagle breeding to the natal area in the northern part of the Sea of Okhotsk, Russia

В паре белоплечих орланов (Haliaeetus pelagicus), занимающих гнездовой участок на р. Кава (заповедник «Магаданский», бассейн р. Тауй, северное побережье Охотского моря), была обнаружена птица с красным кольцом 8E на правой лапе. Впервые орлана с красным кольцом на р. Кава в границах территории обитания пары с гнездового участка m-12 мы встретили 15 августа 2014 г. (рис. 1). Здесь и далее к территории обитания пары мы относим территорию, в пределах которой локализована основная активность In summer 2017 we found a Steller’s Sea Eagle (Haliaeetus pelagicus) carrying the red ring 8E on the right leg. The bird was a member of a territorial pair occupying the M-12 breeding territory at the Kava river, Tauy River basin, Magadan State Nature Reserve, Northern part of the Sea of Okhotsk. A bird with a red ring was first reported at the same breeding territory in August 15, 2014 (fig. 1). At that time we were unable to read the ring number. On July, 22 2015 and in July 2016 we observed an eagle with the ring within proximity of the nest in the M-12 territory (fig. 2). The reading on the ring was tentatively identified as 8C, but it was not a confident sighting. In July 2017 we managed to identify the ring number as 8E. We observed the number via gyroscopic binoculars (Peleng 12×40), spotting scope (Nikon 40×) and took legible photographs (fig. 3). This bird was ringed by us as a chick at the nest Tauy-1/1B on July 29 2007. The nest was located at the Tauy river estuary in a view of the Balagannoe settlement. The M-12 breeding territory was located in the same river system, 90.3 km upstream from the nest Taui-1/1B where the chick hatched. In summer 2017 the age of the bird was 10 years (11 summer). DOI: 10.19074/1814-8654-2018-36-142-147