ABSTRACT Habitat use by remotely tracked Short-eared Owls, tagged in Scotland but travelling widely around Europe and into North Africa, was assessed when they were away from their preferred extensive blocks of moorland and mire habitats. Birds spent 18% of their time away from extensive moorland and mire within landscapes that included pasture and arable farmland and, in some cases, isolated fragments of mire. Within modified farmed or built landscapes, they tended to use patches of seminatural or less intensively managed habitats. No evidence for increased mortality was found when birds were using such fragmented and likely ‘less favoured’ landscapes, with the exception of when in North African deserts. Such places represent an extreme case of habitat fragmentation within a hostile landscape. We present data that suggest a role for fragmented habitat patches within wider modified and hostile landscapes in facilitating the dispersal of mobile species towards higher-quality and more extensive habitats. Ensuring a network of such patches has the potential to increase the resilience of mobile species in its preferred habitat blocks and associated protected-area networks.

ABSTRACT Field surveys and camera traps close to nest sites were used to study the nesting biology of a dense population of Egyptian Vultures Neophron percnopterus on Masirah Island, Oman. Camera-trap images from one nest revealed the laying of a third egg in a nest and incubation of the clutch by three individually identifiable adults (a male and two females). Another male and two females were photographed copulating in a different nest. Behavioural observations revealed the presence of five more probable polygynous trios and another trio with unknown sex composition. A surplus of adult non-breeders was recorded at the traditional main communal roost. The high occurrence of polygynous trios within a dense population, combined with an abundance of non-territorial Egyptian Vultures, may be explained by habitat saturation in a species exhibiting a tendency for natal dispersal that is inversely density dependent.

ABSTRACT The breeding success of Great Tits and Blue Tits using nest boxes at a 12.5-ha site in southwest Scotland has been monitored for 11 years (2014–24). Data collected includes date of first egg laying, clutch size, brood size and brood mass at 11 days old, and fledging success. A short burst of exceedingly heavy rain on a single afternoon in May 2024 resulted in extensive breeding failure: in 2024 there was 49% survival to fledging in Great Tits (n = 7), compared to 74% over the preceding 10 years (n = 40), and 34% in Blue Tits (n = 9) compared to 73% over the preceding 10 years (n = 38), with surviving broods having very low biomass.

ABSTRACT We studied the unusual moult strategy of a small bird with a long breeding season, the Western Common Kingfisher Alcedo atthis ispida, in northwestern Germany, examining remiges and primary coverts of more than 4000 birds after their first wing moult. Kingfishers start renewing remiges in their second calendar year. Despite three moult centres, progress is slow, because the bird’s foraging technique requires a good flight performance. Usually less than 13% of the remex mass in one wing was missing. A complete moult of remiges lasted about 120 days. Kingfishers undertake two to four breeding attempts per season. The interval between the last brood and winter is mostly too short for a complete remex moult. Kingfishers employ two solutions: an overlap between moult and breeding, and a moult suspension, singly or in combination. Many second-calendar-year Kingfishers shed some remiges at the beginning of the second brood and then slowed or halted the moult. Thus a higher proportion of flight-feather mass could be missing during egg laying and incubation than during the more demanding nestling period. In 84% of all moult cases in relevant age classes (n = 1072), birds retained one to 31 old remiges (median seven). In the following year, the moult continued from the point of suspension. If again not all remiges were renewed, the pattern of retained feathers differed from that after the first moult and more feathers with a higher damage risk remained among the same number of unmoulted remiges. Probably to avoid this, especially individuals with a high number of feathers retained after the first moult started the second moult early. Needing a long breeding season because of its r-strategy life cycle, the Kingfisher can probably only inhabit the temperate zone because of its unusual moult.

ABSTRACT During recent decades the Osprey population in Europe has grown and expanded, partly as a result of reintroduction. During 2013–17 a reintroduction programme was conducted in the Bay of Biscay. We describe the autumn movements of 12 GPS-tracked young Ospreys, and the survival of the translocated Ospreys. Using our and external data, we compare survival rates between satellite-tracked Ospreys and those simply ringed and discuss the potential negative effects of satellite devices. Satellite-tagged Ospreys used similar flyways and settled in the usual sub-Saharan wintering region of the Scottish birds but made no stopovers. Of the staging events 26.7% were recorded on electricity infrastructure, which represents a high risk, especially in the countries with a developed network. None of the 13 tracked birds survived to return, whereas the return rate of 41 non-tagged birds was 24.4%. Available information indicates a return rate of 6.2% (five from 80) for satellite-tagged juveniles from European migratory populations, which suggests that tagging is associated with a lower survival. Further investigation is needed to verify whether satellite tagging negatively affects the survival of juveniles. Meanwhile, we advise against satellite-tagging young Ospreys in reintroduction projects, and in other small populations, because it could reduce the chances of success and jeopardise their viability.

ABSTRACT Above all, bird ringing must be safe for birds, for ethical reasons but also to ensure that data collection is not biased by marking effects. Bird ringing schemes are responsible for determining the size of the rings used to mark birds individually. This paper critically reviews the recommended ring sizes in the Aranzadi Ringing Scheme and proposes an objective criterion for ringers. A morphological analysis of tarsus width (MTW) and the width of the tibia–tarsus articulation (MAW), over a sample of more than 4000 individuals of 74 species of both passerines and non-passerines captured in Spain, revealed that the mean difference between the internal diameter of the recommended ring (IDR) and MTW was 32% in relation to MTW (sd 15.8%, 95% confidence interval 28–35%). Experience demonstrates that this clearance is adequate, but recommendations for rings with clearances either too narrow (<6%) or too wide (>50–60%) should be reviewed and changed, if possible, to bring them closer to a 32% standard.

ABSTRACT Claw darkening is a useful sign that Pied Flycatcher Ficedula hypoleuca nestlings are large enough to ring with a British Trust for Ornithology ring size A (internal diameter 2.3 mm), accurately predicting that 99.9% of nestlings can be ringed safely, compared to 99.8% for primary-feather development of ‘feathers short’ and 94.6% for age of five or more days. All Pied Flycatcher nestlings that had dark grey claws and had reached at least the ‘in-pin’ stage of primary-feather development were of a suitable size for ringing.

ABSTRACT Chiffchaffs are common breeding birds in Britain, widely considered to be double brooded, but the timing and outcomes of successive nesting attempts are still poorly understood. Observations of colour-ringed individuals at Wicken Fen revealed that birds in the study population demonstrated high levels of fidelity to mate and to breeding site. Only 52% of nests were successful. Nest failure was recorded at the laying, incubation and chick-rearing stages, but losses during laying accounted for 45% of failed nests. Of late nests that would often be described as second broods, 38% were late replacements for chick-stage failures.

ABSTRACT Given new avenues for Black Grouse Lyrurus tetrix telemetry, and translocations to previously occupied areas, we designed a new cage trap for use at leks that was safe, reliable, and easily transportable, and a custom black-and-white wing-tag that was visible in low light and under camera-trap infrared illumination. The trap was tested over 12 trap days in autumn/winter. Behaviour before and after trapping and marking was monitored with camera traps and then via daily spring watches. The trap was simple to set up and operate, with a quiet closure mechanism that did not typically flush other birds, allowing multiple catches per day. Birds were caught on three quarters of trap days and at a rate of 2.5 birds per hour set. Typically, birds behaved apparently normally around traps and after trapping and tagging, although with some indication of resource-guarding of bait. Lek counts between autumn and spring matched patterns reported from other local leks. Tags were identifiable using camera traps (including with infrared in pre-dawn low light) and via optics. This trapping method could be tested in the spring to assess its ability to catch females, and our approaches could be applied to future telemetry, translocation, behavioural or demographic studies.

ABSTRACT On 4 January 2023 DAP found a dead Swallow on a farm near Auldearn, Nairnshire (57°35’N 3°52’W). The bird appeared to have been dead for three to four weeks but was in a reasonably good state of preservation, probably as a result of the prolonged period of snow and very low temperatures which had prevailed in the area during the second and third weeks of December 2022. The bird, a juvenile, appeared to have reached a stage of moult of its flight feathers which might usually have only been expected in its winter quarters.