Puffinus Yelkouan Research Articles

Spatial risk analysis of floating marine macro litter along the Western Sicilian coast: Overlap with bottlenose dolphin and seabird hotspots.

Marine litter is known to be a major stressor in coastal marine habitats. Therefore, the aim of this study was to identify the areas where species could be most threatened by floating marine macro-litter (FML) The composition and density distribution of FML along the waters of the Agrigento province was monitored from 2019 to 2021, together with the density distribution for the protected species Tursiops truncatus, Hydrobates pelagicus melitensis, Calonectris diomedea, and Puffinus yelkouan.. The areas where marine litter poses the biggest threat to these species were identified by overlapping the core areas of their distribution with that of FML. The results showed that FML’s was mainly composed of plastics (90 %). There was a high degree of overlap between FML’s core area and focal species: 65 % for bottlenose dolphins, 76,3 % for the European storm-petrel, and 85,1 % for the shearwaters. Our findings highlight a key area of about 54 km2, within the 25–70 m depth, where the highest presence of protected species and FML was observed. The high degree of overlap of the species and FML core-areas underlines the need to enact specific management measures.

Offshore distribution of yelkouan shearwaters in the north-western Adriatic Sea

: The yelkouan shearwater Puffinus yelkouan is endemic to the Mediterranean and Black Seas, and classified as Vulnerable in the IUCN Red List. Information on the species’ distribution and habitat use in the eastern Mediterranean is scant, and only a few studies were based on direct visual observations in offshore waters. Here, we provide information on 1) the occurrence of yelkouan shearwaters within a 3000 km2 study area off the region of Veneto, Italy, in the northwestern Adriatic Sea, based on visual surveys conducted from small boats between April and October 2018–2022 (effort: 169 days, 23,836 km), and 2) the geographic, bathymetric and oceanographic variables likely to drive the species’ offshore distribution. Yelkouan shearwaters (238 sightings, 916 individuals) were observed in waters 9–33 m deep, between 2 and 24 km from the coast. Individual counts ranged between 1 and 100, with 95% of the encounters having less than 10 individuals. An Explainable Boosting Machine model – a machine learning technique based on generalized additive models – selected chlorophyll a as the most important variable to explain the species’ occurrence, followed by distance from the coast, and bottom depth. The model indicated a higher occurrence in waters with chlorophyll a less than ~2.3 mg/m3 , farther than ~15 km from the coast, and deeper than ~22 m. The effects of SST, salinity, and day of the year were less clear. This study provides insight into the offshore distribution of yelkouan shearwaters, within one of the Mediterranean areas most exposed to cumulative human threats

The effects of temporally distinct light pollution from ships on nocturnal colony attendance in a threatened seabird

The ecological effects from artificial light are complex and can affect species and life-stages differently. Ships are a dynamic source of light pollution, often brightly lit and temporarily increasing light levels in otherwise relatively dark areas. Because several nocturnal seabird species display reduced activity and avoidance of natural or artificial light, we expect that bright vessel lights may affect colony attendance patterns. Here, we test whether the presence of ships in front of coastal cliffs affects colony attendance in the Yelkouan Shearwater (Puffinus yelkouan). Ship presence at the site was obtained from an automatic identification system database, and a data logger measured light levels at the colony autonomously for four breeding seasons (2017–2020). Moreover, a Radio Frequency Identification (RFID) system was deployed at a cavernous colony entrance to register arrivals and departures of shearwaters. Direct illumination from ships increased cliff face brightness, and colony attendance was significantly reduced in brighter conditions. Ship presence reduced the number of shearwaters entering the colony per hour by a mean of 18% (SD ± 24). Disruption of natural attendance patterns is likely to have short- and long-term effects on breeding success, physiological condition, and colony viability. Therefore, we propose mitigation measures to reduce the impact from commercial shipping on burrow-nesting seabirds. Local regulations are necessary for colony-specific impact reduction, while incorporation of measures such as black-out blinds, fixture shielding and maximum brightness limits into international conventions can have additional far-reaching benefits.

Results of the eighteenth winter waterbird census in Libya in 2022.

Libyan wetlands are diverse; the coastline of Libya, in particular, has different kinds of wetlands, such as salt marshes, bays, lakes, lagoons, and islands. These varieties in habitats provide good shelters and foraging sites for migratory birds during their journeys between Eurasia and Africa. Since the beginning of the Libyan winter census of waterbirds International waterbirds census (Libya IWC) in 2005, which continued regularly until 2012, it has had relatively the same performance in the number of covered sites. However, since 2013, due to the security situation that Libya has experienced due to wars and conflict, which negatively affected the quality of the IWC in Libya, the number of sites has dramatically decreased, reaching only six locations during the middle of the previous decade. The IWC 2022 aimed to count the birds along the Libyan coast from January 10 to 29. The census activities were conducted from dawn to dusk during the study period by using high-quality Telescopes, binoculars, and digital cameras for the documentation. Point transects method was used to cover the sites. The results of this year showed that a total of 64 sites were covered, and 68 species of waterbirds were counted, with an abundance of 61,850 individuals. During the census period, a total of 52 non-waterbird species found in Wetlands were recorded, and the number of individuals was 14,836 birds. A total of 18 threatened species were observed during this survey, 12 of them are mentioned in the International Union for Conservation of Nature Red List, and nine species are mentioned in the regional activities center of specially protected areas annex II as threatened in the Mediterranean, where the species; Larus audouinii (Payraudeau, 1826), Larus genei (Breme, 1839), and Puffinus yelkouan (Acerbi, 1827) are mentioned in both of them. The lack of the number of ornithologists and bird watchers is still one of the factors affecting the quality of the IWC in Libya, as well as lack of funding remains an important factor that plays a major role in the success of the waterbirds census.

Bottlenose Dolphins and Seabirds Distribution Analysis for the Identification of a Marine Biodiversity Hotspot in Agrigento Waters

The aim of this study is to evaluate the presence of biodiversity hotspots in Agrigento waters (Mediterranean Sea) to define the conservation area for bottlenose dolphins (Tursiops truncatus) and seabirds (Calonectris diomedea, Puffinus yelkouan, and Hydrobates pelagicus), according to European directives. With this purpose, the maximum entropy algorithm (MaxEnt) was applied to the sighting points of the focal species. They co-occur in the study area and have been documented to forage behind trawlers. In this study, a fishing rate was designed and used as an explanatory variable of the species distribution, together with physiographic variables. Data were collected during 68 surveys in the waters off Agrigento province. MaxEnt models showed a strong predictive power, with distance from the coast being the greatest predicting variable, followed by slope, depth, and fishing rate. For all the species considered, the probability of presence increased as the fishing rate grew. Cartographic analysis revealed one area shared by the species, which occupies 529 km2, from the shoreline to 100 m depth. This study increases knowledge on the distribution and habitat preferences of the target species in the Sicilian waters. Evaluating the influence of fisheries is a promising method that needs further testing to apply effective management measures.

Productivity changes in the Mediterranean Sea drive foraging movements of yelkouan shearwater Puffinus yelkouan from the core of its global breeding range

AbstractPelagic seabirds are tied to their breeding colonies throughout their long‐lasting breeding season, but at the same time, they have to feed in a highly dynamic marine environment where prey abundance and availability rapidly change across space and seasons. Here, we describe the foraging movements of yelkouan shearwater Puffinus yelkouan, a seabird endemic to the Mediterranean Sea that spends its entire life cycle within this enclosed basin and whose future conservation is intimately linked to human‐driven and climatic changes affecting the sea. The aim was to understand the main factors underlying the choice of foraging locations during the reproductive phases. A total of 34 foraging trips were obtained from 21 breeding adults tagged and tracked on Tavolara Archipelago (N Sardinia, Italy). This is the largest and most important breeding area for the species, accounting for more than 50% of the world population. The relationships between foraging movements during two different breeding stages and the seasonal changes of primary productivity at sea were modeled. Movements appeared to be addressed toward inshore (<20 km), highly productive, and relatively shallow (<200 m) foraging areas, often in front of river mouths and at great distances from the colony. During incubation, the Bonifacio Strait and other coastal areas close to North and West Sardinia were the most preferred locations (up to 247 km from the colony). During the chick‐rearing phase, some individuals reached areas placed at greater distances from the colony (up to 579 km), aiming at food‐rich hotspots placed as far north as the Gulf of Lion (France). The need for such long distance and long‐lasting foraging trips is hypothesized to be related to unfavorable conditions on the less productive (and already depleted) Sardinian waters.

Annotated Checklist of the Marine and Coastal Birds of Lebanon

The study of marine and coastal birds in the Lebanon recorded 75speciesalong the shore line of Lebanon and for a distance of 7 kms offshore.Of those species,35 are seabirdspecies, 38 marine or seawater/freshwater coastal birds, and 2waterbird specieswintering on the archipelagoes of Mina/Tripoli in North Lebanon (Grey Heron and Little Egret)with apparently much affinity to seawater in the winter season. This study highlighted 3 globally threatened species (Leach’s Storm Petrel Hydrobates leucorhoa [Vulnerable], Mediterranean Yelkouan Shearwater Puffinus yelkouan [Vulnerable], and Dalmatian Pelican Pelecanus crispus [Vulnerable]), underlined7 globally Near Threatened avian species, pointed out to 3 species that may be submitted for reconsideration bythe “Lebanon Bird Record Committee” (LBRC) at LCNRS;and updated the data of 9species of high significance from the past studies, of which, 2 species are upgraded from vagrants to winter visitors/passage migrants, one to passage migrant and one to wintervisitor..Regarding the final phenological statusesof species, one is resident breeding, one is summer breeding, 3 are formerly bred, one extirpated (extinct) from Lebanon 31are passage migrant/winter visitors, 25passage migrantsonly, 2winter visitors and 14vagrant species.

Ege Denizi’nde kıyı balıkçılığı ve deniz kuşları arasındaki bazı etkileşimler

In this study, it is aimed to determine the some interactions between various fishery types and seabirds, results of this interaction and sea bird species that have been interacting due to secondary attraction factors. A total of 80 fishermen, working in fish farms, small scale fishery (SSF) and lagoons located in Izmir, Aydın and Muğla were face-to-face interviewed between September 2016 and December 2018. The great cormorant (Phalacrocorax carbo), yellow-legged gull (Larus michahellis), great white egret (Ardea alba), some yelkouan shearwater (Puffinus yelkouan) and great white pelican (Pelecanus onocrotalus) are the bird species that have an interaction with coastal fishermen and sea-cage fish farms. 82% of employees in sea-cage fish farms mentioned that they have an interaction with sea birds in winter, besides %50 of SSF have an interaction with sea birds in summer. The difference between interaction rate according to seasons has been found as statistically significant (p<0.05). 33% of employees in fish farms expressed that they see sea birds during the day. This ratio is 21.7% and 15% for SSF and fishermen in lagoon, respectively. Furthermore, 8.3% of fishermen in lagoon, 11% of employees in fish farms and SSF mentioned that they have an interaction with seabirds especially in the morning time.

Patterns of at-sea behaviour at a hybrid zone between two threatened seabirds

Patterns of behavioural variation and migratory connectivity are important characteristics of populations, particularly at the edges of species distributions, where processes involved in influencing evolutionary trajectories, such as divergence, mutual persistence, and natural hybridization, can occur. Here, we focused on two closely related seabird species that breed in the Mediterranean: Balearic shearwaters (Puffinus mauretanicus) and Yelkouan shearwaters (Puffinus yelkouan). Genetic and phenotypic evidence of hybridization between the two species on Menorca (the eastern and westernmost island in the breeding ranges of the two shearwaters, respectively) has provided important insights into relationships between these recently diverged species. Nevertheless, levels of behavioural and ecological differentiation amongst these populations remain largely unknown. Using geolocation and stable isotopes, we compared the at-sea movement behaviour of birds from the Menorcan ‘hybrid’ population with the nearest neighbouring populations of Balearic and Yelkouan shearwaters. The Menorcan population displayed a suite of behavioural features intermediate to those seen in the two species (including migration strategies, breeding season movements and limited data on phenology). Our findings provide new evidence to support suggestions that the Menorcan population is admixed, and indicate a role of non-breeding behaviours in the evolutionary trajectories of Puffinus shearwaters in the Mediterranean.

Pre-laying movements of Yelkouan Shearwaters (Puffinus yelkouan) in the Central Mediterranean

The pre-laying exodus (PLE) is considered a crucial period in the breeding biology of Procellariiformes as it determines the success of egg production within a season and, therefore, a population’s reproductive output. However, it has scarcely been studied compared to other stages of the annual cycle. Here we present the first pre-laying tracks of the vulnerable Yelkouan Shearwater (Puffinus yelkouan) through the Global Positioning System tracking of birds breeding on the Maltese islands in the Central Mediterranean, and compare PLE core utilisation areas to known areas used during the chick-rearing period. Females spend, on average, 13 days foraging during egg development, reaching an average maximum distance of 325.5 km from their breeding colony to forage at offshore areas mainly south of the Maltese islands; these journeys are of longer duration and cover a greater distance than those undertaken by males, and by females that are not developing an egg, during the same period. There is little to no overlap between the PLE core utilisation areas and those used during chick-rearing by the same populations. This confirms our expectations that the PLE differs from foraging trips undertaken outside of the egg development period. Our results highlight the need for more research into the factors attracting egg-producing females to the PLE foraging areas and the importance of trans-boundary marine protection for the conservation of vulnerable seabirds.

Status and distribution of migrating and breeding marine birds in north Lebanon.

The study of marine birds in the northern part of Lebanon recorded 2681 individuals, distributed over 86 species. Among them 35 are foreshore species, 18 coastal, 6 maritime, 9 ducks, 6 herons, 9 various saltwater related species and 3 terrestrial. The highest density is shown by the yellow-legged Gull Larus michahellis and common blackheaded gull Chroicocephalus ridibundus. The globally vulnerable yelkouan shearwater Puffinus yelkouan, an endemic species to the Mediterranean, appears on the 9th rank in the classification of seabird species from the more to the least abundant, highlighting as such, beside other 6 globally near threatened species, the role that Lebanon can play in improving the conservation status of these species. Regarding the phenological status of species, 48 are passage migrant/winter visitors, 31 passage migrants, 5 winter visitors and 2 vagrant species. The surveys revealed that three coastal seabird species (Armenian gull Larus armenicus, slender-billed gull Chroicocephalus genei and sandwich tern Thalasseus sandvicensis) and one ubiquist species (Eurasian Golden Plover Pluvialis apricaria) are not rare as it was believed in previous papers but fairly common winter visitors. The study identified the yellow-legged gull breeding population to be 160 couples, and confirmed the second and third breeding records of the little ringed plover Charadrius dubius.

Control of invasive species for the conservation of biodiversity in Mediterranean islands. The LIFE PonDerat project in the Pontine Archipelago, Italy

We present the EU LIFE PonDerat project, which is aimed at restoring the natural ecosystems of the Pontine Archipelago, a group of islands located off the western coast of Italy. The spread of invasive species is a major environmental threat on these islands, which are rich in rare habitats and endemic species and are important sites for the conservation of Mediterranean biodiversity. The project focuses on the conservation of species and habitats that are protected by EU laws but are currently threatened by introduced plants and animals. The main targets of the control measures are black rats, feral goats, mouflons and invasive plants of the genus Carpobrotus. Conservation measures focus on the shearwaters Puffinus yelkouan and Calonectris diomedea, which are endemic to the Mediterranean and are listed in Annex I of the European Bird Directive. Conservation measures also focus on island habitats of great biogeographical value, which are listed in Annex I of the European Habitats Directive and are seriously threatened by introduced herbivores and by invasive plants. The main outcome expected from this project is that the restoration of ecosystem functions will enhance the breeding success and population size of shearwaters and lead to the recovery of target habitats.

Predicting foraging hotspots for Yelkouan Shearwater in the Black Sea

The Yelkouan shearwater (Puffinus yelkouan) is a vulnerable species endemic to the Mediterranean Region, but there is little information of its ecology particularly when at sea. In this study, we assessed the habitat use by Yelkouan shearwater in the Black Sea during the breeding (March–July) and non-breeding (August–February) periods of 2013, using boat-based surveys and shore-based counts. We created a species distribution model (SDM) based on the environmental variables that most accurately reflected the oceanographic habitat of this species in order to delineate foraging hotspots. Our habitat modelling analyses suggest that Yelkouan shearwaters respond to complex bio-physical coupling, as evidenced by their association with oceanographic variables. Foraging Yelkouan shearwaters mainly occurred on the western Black Sea continental shelf, indicating that Yelkouan shearwaters were foraging in shallow, cold and coastal waters. In the non-breeding period, Yelkouan Shearwater occurred beyond the Black Sea continental shelf, a wide pelagic extension of sea, indicating that shearwaters foraged in deep, warm and pelagic waters. These results are consistent with earlier studies, which identified the Black Sea as an important congregation site for Mediterranean Yelkouan shearwater populations outside the breeding season. This study demonstrates how the integration of boat-based survey data, shore-based counts and modelling can provide a wider understanding of the linkage between marine ecosystems that is mediated by marine megafauna such as pelagic seabirds.

Habitat overlap between bottlenose dolphins and seabirds: a pilot study to identify high-presence coastal areas in the Tyrrhenian Sea

The identification of foraging hotspots able to support the co-existence of multiple top predators provides a potential approach to addressing protection measures for marine ecosystems. In this study, we conducted visual surveys in the central Tyrrhenian Sea to determine areas with simultaneous presence of bottlenose dolphins, four species of seabirds (Audouin's gull, Yellow-legged gull, Yelkouan shearwater and Cory's shearwater), and baitballs occurring at the surface, indicating the presence of potential prey items. We also analysed their occurrence in relation to topography (depth, slope and distance from the shore) and seabed types. Kriging analysis identified areas with simultaneous presence of several marine top predators. Dolphin distribution appeared to be linked to gentle slope (6–10 m) and muddy seabed, possibly associated with prey distribution, whereas the four seabird species were more frequent in areas with a water depth of 100–150 m, gentle slope and muddy seabed, apart from Audouin's gull, which preferred a depth of 10–20 m. Baitball distribution was linked to depth (20–40 m), gentle slope (6–10 m) and muddy seabed. The overlapping presence of bottlenose dolphins, seabirds and baitballs allowed the identification of foraging areas, presumably representing biodiversity and productivity hotspots, located in waters of 50–100 m depth at the mouths of two rivers. This approach provides a promising tool for identifying highly productive coastal areas, and should also be recommended for wider-scale surveys.

Are artificial burrows efficient conservation tools for seabirds? A case study of two sympatric shearwaters on neighbouring islands and guidelines for improvement

Seabirds are one of the most threatened animal taxa worldwide as they have to deal with threats both at sea and on their breeding grounds. One of these threats is the loss and deterioration of their nesting habitat. Here, we evaluated the long-term effectiveness of providing artificial burrows for the conservation of Yelkouan (Puffinus yelkouan) and Scopoli's (Calonectris diomedea) shearwaters on two islands of the Hyères archipelago (Mediterranean, France). We estimated and compared the longevity, occupancy of and breeding success in artificial burrows and natural cavities. We also analysed factors affecting these three parameters in artificial burrows to optimize their installation for the conservation of our study species. Although their efficacy depended on the species and the island considered, artificial burrows provided more stable and persistent breeding habitat (12-years persistence: 80% vs. 72%), allowed the recruitment of new breeders and good reproductive success (49–76%), and probably reduced inter-specific competition for nesting cavities, across the two islands. The characteristics of both artificial burrows and the areas where they were installed affected artificial burrow efficacy in terms of longevity and occupancy by shearwaters. Thus, artificial burrows were successful tools for the conservation of these two Mediterranean species of shearwaters, particularly when their design and installation were optimized by limiting the risk of their destruction and by selecting burrow and habitat characteristics that enhance their occupancy by the target species. The evaluation of such conservation measures should be performed for every species and site to help managers design and implement effective conservation plans.

Island specificities matter: cat diet differs significantly between islands of a major breeding archipelago for a vulnerable endemic seabird

Domestic cats are one of the most widespread predators on islands worldwide and are responsible for numerous reductions and extinctions of species on islands. The three main islands of the Hyeres Archipelago house one of the largest colonies of the Mediterranean endemic Yelkouan shearwater Puffinus yelkouan that has recently been up-listed by the IUCN to ‘vulnerable’. The main objectives of this study were to assess the diet of cats and to study the effect of cat predation on Yelkouan shearwater populations at the archipelago scale. The diet of cats was studied using scat analyses according to years and seasons for each island. Simultaneously, Yelkouan shearwater breeding success was monitored during a period of 8 years on Port-Cros and Porquerolles, and 3 years on Le Levant. Descriptive analyses and GLM were used to compare data gathered on each island. At the archipelago scale, cats preyed strongly upon introduced mammals and shearwaters. Surprisingly, large differences appeared in cats’ diet according to the island considered. The Yelkouan shearwater was the primary prey of cats on Le Levant, but secondary on Port-Cros and Porquerolles. Cat predation was mainly concentrated during the shearwater prospecting period, when birds arrive at the colonies and look for a mate (if they are not already paired) and a burrow before breeding. Consequently cat impact was low on shearwater breeding success. However, this study demonstrates that the cat management conducted on Port-Cros was positive for fledging success. The successful cat eradication on Port-Cros supports the need to continue working for Yelkouan shearwater conservation with Le Levant as a priority, because this is where the colonies are largest and predation on Yelkouan shearwaters is very high.

First steps in studying cat movement behaviour through VHF tracking at a major world breeding site for the mediterranean endemic yelkouan shearwater

Premières données de l’étude par radio-pistage VHF des déplacements des chats dans un site majeur de reproduction du Puffin Yelkouan, endémique de Méditerranée. — Le chat représente un des prédateurs invasifs les plus menaçants pour les espèces natives des îles et particulièrement pour les oiseaux marins adultes qui sont fortement vulnérables à la prédation. Les populations du Puffin Yelkouan, espèce endémique du bassin méditerranéen, sont réparties en quelques grandes colonies de reproduction et sont en voie de déclin, notamment du fait de l’impact des chats harets et errants. Dans une étude précédemment publiée, l’impact des chats introduits sur la population de puffins de l’île du Levant a été évalué au travers du régime alimentaire du chat sur une période de deux ans. Cette étude a mis en évidence que les chats consommaient trois proies principales : le Lapin, le Rat noir et le Puffin Yelkouan, et qu’un pic de prédation de puffins était observé dès leur arrivée sur les colonies (période de prospection). Nous avons donc cherché à compléter ce travail par une étude préliminaire visant à étudier les patrons de mouvement de quatre chats (trois chats harets et un chat domestique) via un suivi VHF (very high frequency), dans le but d’analyser leurs comportements individuels et leurs domaines vitaux sur l’île du Levant, qui est l’un des principaux sites de reproduction du Puffin Yelkouan. Nos résultats montrent que deux des trois chats harets ont été détectés dans les colonies de puffins durant les périodes de prospection et de reproduction de cet oiseau marin alors que le chat domestique n’a jamais été détecté dans ces colonies. Cela suggère que les patrons de déplacement des quatre chats suivis puissent être liés à la présence des puffins dès que ces oiseaux marins arrivent à la colonie. Les chats suivis montrent des domaines vitaux de taille relativement réduite, plus larges pour les chats harets qui couvrent de plus grandes distances, et avec des territoires chevauchants, que pour le chat domestique. Ces résultats préliminaires de patrons de déplacements, couplés aux résultats précédents de prédation du chat sur le Puffin Yelkouan, nous indiquent que l’impact du chat haret se doit d’être limité. Cet objectif doit être atteint en effectuant une stratégie de gestion efficace qui tiendrait compte des patrons de déplacements des chats afin d’éviter l’épuisement d’un des sites de reproduction les plus importants pour cette espèce de puffin endémique de Méditerranée.

British Ornithologists' Union Records Committee: 43rd Report (October 2014)

British Ornithologists' Union Records Committee: 43rd Report (October 2014)

Relationships Between Nest-Cavity and Mate Selection, Reproductive Performance and Fidelity in the Mediterranean Endemic Yelkouan ShearwaterPuffinus yelkouan

Nest and mate choice is important in seabirds, influencing reproductive performance as both nest-site and partner quality varies. The Yelkouan Shearwater Puffinus yelkouan nests mainly in pre-existing cavities and to a lesser extent in cavities it excavates. We have monitored breeding colonies of the Yelkouan Shearwater on two islands of the Hyères archipelago, south-east of France, for nine years to analyse nest-cavity and mate selection, to evaluate nest-cavity and mate fidelity, and to investigate their relationships with reproductive performance. Yelkouan Shearwaters selected nest-cavities providing a high degree of concealment and protection. Reproductive performance and fidelity to cavity were highest in deep cavities with a winding tunnel and a steep slope around the entrance. Mating was assortative for bill and tarsus measurements. High rates of return to the same cavity (94.7%) and mate (95.5%) were recorded. Fidelity to nest-cavity was highest when breeding succeeded the previous year (fidelity rate: 97.3% in successful breeders vs. 87.8% in unsuccessful breeders) and was most likely to result in successful breeding the same year (breeding success: 67.5% in faithful breeders vs. 43.8% in movers). The rate of divorce was low (4.5%), did not differ between islands and was not associated with breeding performance. However, breeding success increased by 22.2 ± 9.9% after mate change following a divorce or the absence of a previous mate. Such high rates of nest-cavity and mate fidelity could indicate a good population status with breeding habitat, food resource and mates of good quality.

British Ornithologists' Union Records Committee: 42nd Report (October 2013)

British Ornithologists' Union Records Committee: 42nd Report (October 2013)