How far animals travel to gather food for offspring or themselves is a central component of ecology. Among birds, the ‘foraging range’ (straight-line distance between a central place and a destination) is used to assess potential interactions with anthropogenic stressors such as wind farms. Recent reviews have summarized marine foraging ranges for UK breeding seabirds. However, for species that span the terrestrial/marine divide (some gulls, terns, sawbills and divers), terrestrial ranges are unknown, as is an understanding of how ranges may vary by breeding colony and their surrounding habitat. Using global positioning satellite (GPS) telemetry, we studied the movements of Lesser Black-backed Gulls Larus fuscus and Herring Gulls L. argentatus from 11 and seven UK breeding colonies, respectively, over 12 years. We investigated the variation in foraging range using general mixed effects models with respect to: (i) terrestrial and marine environments; (ii) stages of the breeding season; and (iii) colony types according to habitat (natural: island, coastal, inland; and urban: coastal), accounting for sources of potential sampling bias. Lesser Black-backed Gulls had significantly larger ranges than Herring Gulls. During likely active nesting periods (incubation and chick-rearing: ‘true breeding’), marine foraging ranges of Lesser Black-backed Gulls (local mean 19.5 ± 23.1 km, max 175.5 km) were greater than terrestrial ranges (local mean 14.9 ± 15.9 km, max 145.4 km). By contrast, terrestrial ranges were largest for Herring Gulls (terrestrial, 9.1 ± 10.7 km, max 83.8 km; marine, 7.1 ± 8.1 km, max 74.4 km). For terrestrial environments, true breeding foraging ranges of Lesser Black-backed Gulls were smaller than during pre- or post-breeding phases, whereas for Herring Gulls the reverse was true. Marine ranges of both species were smallest during pre-breeding and largest during post-breeding phases. For both species, urban colonies had the smallest foraging range and island colonies some of the largest. Terrestrial and marine foraging ranges were predicted UK-wide based on colony type and breeding phase, highlighting concentrations of foraging range. This study provides more precise foraging range information specific to foraging environment, breeding stage and colony type than has currently been available, and will therefore help to reduce uncertainty in the consenting process for proposed developments as well as in licensing control of wild birds.
Interspecific competition profoundly influences the ecology of species, and climate change is expected to alter the strength of interspecific interactions. Using long-term data from sympatric breeding populations of the Western Barn Owl Tyto alba (hereafter Barn Owl) and the Tawny Owl Strix aluco in southern Hungary, we explored the associations between the owl species' (i) breeding phenology (annual median laying dates) and regional weather components (daily precipitation, temperature minimum and maximum), (ii) temporal trends of median laying dates and the associated weather signals, and (iii) reproductive output (laying date, clutch size, fledgling number) and the co-occurence of the two species in the same nestbox during the same breeding season. In the Barn Owl, breeding onset was negatively associated with daily temperature maximum, and advanced by 2 weeks in the study period, while the Tawny Owl breeding onset did not change. We found that when the two species used the same nestbox, the breeding of Barn Owls (occurring after the Tawny Owl breeding) was delayed by a month, and they produced one more egg and owlet on average, but second clutches were practically absent, compared to cases when no interaction occurred in the same nestbox during the same breeding season. In contrast, when nesting in boxes later occuppied by Barn Owls, the Tawny Owl's breeding started a few days earlier with an increased clutch size, although with no difference in the number of fledglings. Our results suggest that climate change could heighten competition for nest-sites between the two owl species, as the Barn Owl's breeding season has shifted closer to the breeding season of the Tawny Owl through the study period in parallel with rising temperatures.
The disappearance of the breeding population of Peregrine Falcon Falco peregrinus from Hungary in 1964 is likely to have been caused by extensive agricultural use of organochlorine pesticides. After proving harmful to humans and wildlife, organochlorine pesticides were banned in North America and many European countries, leading to a recovery in Peregrine populations and other raptors in most parts of the world. In Hungary, Peregrines returned as a breeding species in 1997. Using 26 years (1997–2022) of monitoring data, we investigated spatio-temporal patterns in site occupancy and reproductive success during population recovery. We found that: (i) Peregrines initially re-occupied traditional territories in mountainous and forested regions where suitable nest-sites were available on cliffs and in quarries; (ii) the Peregrine population then slowly expanded to lower elevations, predominantly agricultural areas, where they nested in trees and in artificial nest-sites on pylons; (iii) the overall mean (se) probability of successful nesting was 0.713 ± 0.02 and the average brood size (number of young per successful nesting attempt) was 2.56 ± 0.04, with spatial and temporal variation in both measures of reproductive success; (iv) March precipitation had a negative effect on brood size in the wettest region; (v) higher greenness levels in February negatively affected nesting success in the least forested region; and, finally, (vi) Peregrines breeding in artificial nestboxes on pylons had higher nesting success than pairs breeding in natural nests. Our results suggest that the general recovery pattern of Hungarian Peregrines was similar to those observed in other parts of Europe, but also highlight spatial variation in demographic parameters.
Highly pathogenic avian influenza (HPAIV) caused widespread mortality and breeding failure among many wild, avian populations in Europe and North America in 2021–2023, but most populations exhibited a marked reduction in mortality in the year following an outbreak, suggesting that surviving individuals may have developed immunity. A critical mechanism for population resilience is whether individuals that have survived the disease show reduced breeding success because of the potential costs associated with recovery, notably elevated immune defence. We found that, at two UK colonies, the breeding success of Northern Gannets Morus bassanus with black eyes (an indicator of past exposure to HPAIV) was similar to those with normal blue eyes in the year following a severe disease outbreak, suggesting that population recovery may not be hampered by lower reproductive performance of recovered individuals compared to those that were unexposed. However, breeding success, irrespective of past exposure, was lower than the long-term average, suggesting potential carry-over effects on all individuals from the extensive disruption caused by the epidemic the previous year.
We used Google Earth imagery to remotely map 263 potential and confirmed breeding colonies of the Critically Endangered Rüppell's Vulture in seven countries of East and Central Africa. The main aggregations were found in: central and east-central Chad and west and north Darfur in Sudan; south Kordofan state in Sudan; east Sudan and western Eritrea; and southern and southeastern South Sudan. This is the first study to use satellite data to map the breeding distribution of a bird of prey in a large part of its global range. The survey provides guidance for future field research that could seek to verify and monitor the status of these important breeding colonies for a Critically Endangered species.
The Editors and Associate Editors of IBIS depend heavily on the expertise of independent reviewers. We thank our colleagues for their contributions. Their expertise and constructive criticism ensures the highest standards are maintained. The following served as referees during the period 1 July 2024, to 30 June 2025.
Goijman, Andrea
Aarif, KM
Adamík, Peter
Aguillon, Stepfanie
Alexey, Opaev
Almasi, Bettina
Angelier, Frederic
Arct, Aneta
Arroyo, Iñigo
Assandri, Giacomo
Avilés, Jesús
Baguette, Michel
Ballentine, Barbara
Barba, Emilio
Barve, Sahas
Basile, Marco
Batisteli, Augusto
Bayne, Erin
Bernat-Ponce, Edgar
Berr, Tristan
Beskades, Vedat
Best, Julia
Biffi, Sofia
Birkhead, Tim
Blomqvist, Donald
Bocher, Pierrick
Bodey, Thomas
Border, Jennifer
Borger, Mirjam
Bouchri, Haytem
Bradfer-Lawrence, Tom
Brumm, Henrik
Budka, Michal
Bulla, Martin
Burger, Claudia
Burgess, Malcolm
Burton, Niall
Buxton, Rachel
Camphuysen, C.
Capilla-Lasheras, Pablo
Carlson, Nora
Carneiro, Camilo
Cevenini, Devon
Champagnon, Jocelyn
Chibesa, Moses
Childers, Jackie
Clarke, Jennifer
Cohen, Jonathan
Collar, Nigel
Colombo, Martín Alejandro
Coppinger, Brittany
Crates, Ross
Cuervo, Andrés M.
De la Hera, I
Dehnhard, Nina
Diamond, Tony
Dingle, Caroline
Dobney , Sarah
Dunning, Jamie
Duriez, olivier
Edney, Alice
Eens, Marcel
Efrat, Ron
Einarsson, Árni
Evans, Karl
Falk, Knud
Fandos, Guillermo
Fargevieille, Amélie
Farras, Kevin
Fasola, Mauro
Fattorini, Niccolo
Favaro, Livio
Ferreira, André C.
Fijn, Ruben C.
Flack, Andrea
Fleishman, Abram
Flesch, Elizabeth
Foote, Jenn
Francisco, Mercival
Furness, Robert
Gagliardo, Anna
Gameiro , João
García-Campa, Jorge
Geen, Graham
Gill, Robert
Gillies, Natasha
Gilliland, Scott
Grabarczyk, Erin
Green, Andy
Griffith, Simon
Guillemain, Matthieu
Gunawardena, Medhisha
Hammer, Sjúrður
Hampton, Stephen
Hartley, Ian
Healy, Susan
Heintz, Anne-Caroline
Hewson, Chris
Hinke, Jefferson
Hird, Sarah
Hofmeister, Natalie R.
Horrocks, Nicholas
Hughes, Robert
Hung, Chih-Ming
Hunt, David
Huryne, Eugene
Inigo-Elias, Eduardo
Jähnig, Susanne
Jankowski, Jill
Jaramillo, Alvaro
Jedlikowski, Jan
Jiang, Aiwu
Jiménez, Rosa Alicia
Joel, Yitmwa
Johnson, Jeff
Joseph, Leo
Karell, Patrick
Kaur, Jasmeen
Kempenaers, Bart
Kent, Cody
King, David
Klinck, Holger
Knight, E
We evaluate whether a Neolithic engraved rock image at the Alta archaeological site in Finnmark, Norway – of a bird being held by a person – represents a Great Auk Pinguinus impennis. There are several thousand engraved animal figures at Alta, created between 5000 and 2000 years ago, in various hunting panoramas. Of these images, 24 represent aquatic birds, including four others that might also be Great Auks. Based on the size of the bird relative to the person holding it, the size and shape of the beak, wings and webbed feet, and comparisons with some other bird images at Alta, we conclude that it is likely that this one does represent a Great Auk.
Amplitude, or intensity, of sound is a fundamental characteristic of acoustic communication, with relevance in many scientific fields. The amplitude of an animal's acoustic signal at its source (‘source amplitude’) may be particularly relevant in the field of acoustic allometry, where relationships between species' physical and acoustic features (e.g. dominant frequency) have been well-established across taxa. However, despite their potential scientific value, records and studies of source amplitude remain remarkably scarce for avian species. Here we present novel estimates of source amplitude (range and median) for 17 species of Arctic-breeding birds, derived from measurements made in Utqiaġvik, Alaska, during June 2024. We found a strong positive correlation between body-mass and source amplitude in these data via Markov chain Monte Carlo multivariate generalized linear mixed models (MCMCglmms). This relationship was influenced by both phylogenetic and individual identity. In contrast, effects from environmental factors and measurement characteristics were minimal. Our work represents one of few studies that explicitly model an interspecific relationship between source amplitude and body mass across avian genera. We hope that this study will spur further investigations into avian source amplitude and its relationship to morphological and life-history features for species in the Arctic and elsewhere.
Waterbirds distributed in semi-arid and arid regions seem to have adapted their behaviour to the availability and seasonality of wetlands, increasing their mobility range. The Marbled Duck Marmaronetta angustirostris is a threatened waterbird that shows trans-Mediterranean movements but these are poorly known. In a conservation effort, there are two captive-breeding programmes in Spain. Each year captive-bred individuals are released in two main sites: Doñana and surroundings (southwest Spain) and the southern wetlands of Alicante (southeast Spain). In 2018, a GPS/GSM tagging project was launched to monitor the species to facilitate an understanding of their movement patterns and to assess the effects of captive breeding on the adaptation of individuals to the wild. This study presents the first description of long-distance movements between North Africa and Europe by Marbled Ducks. Of the 144 GPS-tagged individuals, only 18 crossed into Africa, the majority were wild-born (n = 14) and only four were from the captive breeding programme, indicating a strong effect of origin on the likelihood of undertaking long-distance movements. Our results showed that long-distance movements were not restricted to the wintering season but also occurred during the breeding season, showing a clear temporal pattern between the two main release/tagging sites: individuals from the southwest crossed mainly in April, whereas those from the southeast did so mainly in October. Birds showed heterogeneous movements at the individual scale (cumulative daily distance moved ranged from 0.1 to 447 km/day). Marbled Ducks performed significantly longer daily displacements during their time in North Africa than those observed in Spain. These findings reveal the complexity and flexibility of movement strategies in this nomadic species and suggest that long-distance movements are individual responses to environmental conditions and wetland availability. Furthermore, we discuss possible explanations for the observed differences in long-distance movements between wild-born and captive-bred individuals. These insights into the seasonal patterns and origin-related differences in long-distance movements are crucial for informing more effective conservation strategies for this endangered species.

