COMPARISON OF THE DIET OF BREEDING AND NONBREEDING CAPE GANNETS MORUS CAPENSIS

Berruti, A. 1991. Comparison of the diet of breeding and nonbreeding Cape Gannets Morus capensis. Ostrich 62:8-12.

The effects of breeding status on the diet composition of Cape Gannets Morus capensis were tested at two colonies in the western Cape, South Africa. At both colonies, there were no significant differences in the species composition of the diet, but the mean energy content of regurgitations of breeders was significantly greater. Although the regurgitations of breeders were heavier and contained more fish at both colonies, only the number of fish per regurgitation from breeders at one colony was significantly greater. Birds feeding chicks at Malgas Island took significantly shorter fish than nonbreeders. The small effect of breeding status on prey species composition shows that temporal and geographical variation in prey availability is more important than breeding status in affecting diet cornposition of the Cape Gannet.     

Lumbering the gauntlet: Cape Gannet fledglings killed by African Penguins

This account presents the first known observations of Cape Gannet Morus capensis fledgling mortalities as a result of aggressive nest defence behaviour by African Penguins Spheniscus demersus. Observations were conducted in 2013 on Bird Island, Algoa Bay, South Africa – the world's largest breeding colony of Cape Gannets. Twentyeight attacks were witnessed between 21 March and 18 May 2013 of which 16 resulted in mortality. The absence of previous observations of this phenomenon may be due to an unusually high proportion of African Penguin chicks being present relatively early on in the breeding season, associated with a potential for increased nest defence at this stage, and a larger number of gannet fledglings that year compared to previous years over the same period.     

Responses by four seabird species to a fluctuating availability of Cape Anchovy Engraulis capensis off South Africa

In recent years, Cape Anchovy Engraulis capensis has been the most important food for four seabirds breeding in South Africa–African Penguin Spheniscus demersus, Cape Gannet Morus capensis, Cape Cormorant Phalacrocorax capensis and Swift Tern Sterna bergii. Between 1984 and 1992, biomass of spawning anchovy fluctuated between about 0.5 and 1.75 million tons. Abundance of anchovy was significantly related to numbers of chicks fledged by African Penguins, occurrence of anchovy in the diet of Cape Gannets and numbers of Cape Cormorants and Swift Terns that attempted to breed. Numbers of African Penguins and Cape Gannets that attempted breeding probably also were influenced by abundance of anchovy. African Penguins and Cape Cormorants abandoned nests when anchovy were scarce and deferred breeding until anchovy became more plentiful. Survival of immature African Penguins in a period of anchovy scarcity was enhanced by availability of South African Sardine Sardinops sagax as an alternative food. When anchovy abundance was low, Cape Gannets fed on sardine.     

The status and conservation of the Cape Gannet Morus capensis

The Cape Gannet Morus capensis is one of several seabird species endemic to the Benguela upwelling ecosystem (BUS) but whose population has recently decreased, leading to an unfavourable IUCN Red List assessment. Application of ‘JARA’ (‘Just Another Red-List Assessment,’ a Bayesian state-space tool used for IUCN Red List assessments) to updated information on the areas occupied by Cape Gannets and the nest densities of breeding birds at their six colonies, suggested that the species should be classified as Vulnerable. However, the rate of decrease of Cape Gannets in their most-recent generation exceeded that of the previous generation, primarily as a result of large decreases at Bird Island, Lambert’s Bay, and Malgas Island, off South Africa’s west coast (the western part of their range). Since the 1960s, there has been an ongoing redistribution of the species from northwest to southeast around southern Africa, and ～70% of the population now occurs on the south coast of South Africa, at Bird Island in Algoa Bay, on the eastern border of the BUS. Recruitment rather than adult survival may be limiting the present population; however, information on the seabird’s demographic parameters and mortality in fisheries is lacking for colonies in the northern part of the BUS. Presently, major threats to Cape Gannet include: substantially decreased availability of their preferred prey in the west; heavy mortalities of eggs, chicks and fledglings at and around colonies, inflicted by Cape Fur Seals Arctocephalus pusillus and other seabirds; substantial disturbance at colonies caused by Cape Fur Seals attacking adult gannets ashore; oiling; and disease.     

Behavioural responses of young cape gannets Sula capensis to high ambient temperatures

A young Cape Gannet Sula capensis responded to high ambient temperatures in the laboratory by standing, gular fluttering with raised head and open bill, wing drooping, defaecating at a fast rate close to or onto the feet, “paddling”; in the excreta, and increased breathing rate. Standing initially caused a decline in foot temperature which rose with rising ambient temperature. Gular flutter and wing drooping assisted the bird in tolerating heat stress. Reduction in heat‐load occurred when standing on a wet surface, presumably due to evaporative heat loss (of excreta on the feet = urohidrosis) and an enhanced conduction of heat to substrate. Field observations confirmed that young Cape Gannets defaecate onto their feet at high ambient temperatures. This species appears preadapted for this behaviour since it builds a solely guano nest, defaecating onto the rim which is compacted by “paddling”;.     

THE DIET AND IMPLICATIONS OF DIETARY CHANGE OF CAPE GANNETS ON BIRD ISLAND,ALGOA BAY

Batchelor, A. L. & Ross, G. J. B. 1984. The diet and implications of dietary change of Cape Gannets on Bird Island, Algoa Bay. Ostrich 55:45-63.

The diet of the Cape Gannet Sula capensis breeding on Bird Island, Algoa Bay, South Africa, was investigated. Approximately 2000 regurgitations representing 13300 prey items were examined. Twenty-three teleost and two cephalopod species were recorded in the diet. More than 90 % of the numerical composition consisted of the three species Pilchard Sardinops ocellata, Anchovy Engraulis capensis and Saury Scomberesox saurus. The proportions of these three species in the diet changed during the sampling periods. These changes were not related to the implied migration patterns of these species. Chick growth rates were investigated in conjunction with the dietary study. These results indicated that Cape Gannet chicks on a diet of Pilchard and/or Anchovy were more likely to fledge successfully than those on a diet of Stockfish Merluccius capensis or Saury. These observations were based on differences in growth rate, and peak and fledgling mass, The data suggest that Pilchard is a preferred prey species and its presence or absence in regurgitationsMayreflect a similar situation on the feeding grounds. The observed increase in the Bird Island gannet populationMaybe related to the availability of high-quality food and consequent reduced pre-breeding mortality. In the absence of historical dietary data, further detailed population dynamics studies are required to support this supposition.     

Gill Memorial Medal Address Holding the mirror up to nature

Since the early 1980s, there have been large decreases in numbers breeding in South Africa of three seabirds that compete with fisheries for food: African Penguin Spheniscus demersus, Cape Cormorant Phalacrocorax capensis and Bank Cormorant P. neglectus. By contrast, two other species that compete with fisheries but which have a larger foraging range when breeding or are nomadic between breeding localities, Cape Gannet Morus capensis and the nominate race of Swift Tern Thalasseus bergii bergii, have increased. Five seabirds that do not compete with fisheries for prey have maintained stable populations or increased. The decreases in the three species have led to deterioration in the overall conservation status of South Africa's seabirds, of which 10 of 15 species (67%) are presently classified as Threatened or Near-threatened, including six of the seven species that are endemic to the Benguela ecosystem off western southern Africa.     

7. SHORT NOTES

Randall, R. and Ross, G. J. B. 1979. Increasing population of Cape Gannets on Bird Island, Algoa Bay, and observations on breeding success. Ostrich 50:168-175.

The South African Gannet Sula capensis on Bird Island has doubled in numbers between 1956 and 1974 and the process is continuing. The increase is similar to that of the two closely related species S. serrator and S. bassana. We estimated from the colony surface area and nest density that the number of birds with nests in 1974/5 was approximately 77 000. Making allowance for non-breeders, there were about 100 000 adults in 1974/5. Guano harvests from 1938–75 show considerable annual fluctuations with an overall downward trend. Poor agreement was found when relating guano harvests to population estimates, when the latter are gauged by colony surface area. We suggest that guano harvests are not good indicators of gannet population trends on Bird Island, primarily because of harvesting methods and environmental conditions. The number of chicks which fledged in the 1976/7 season in a section of the colony was far fewer than expected, even when allowances were made for egg-loss and chick mortality. A combination of heavier-than-usual rainfall and poor management techniques have resulted in high egg-loss and low chick numbers.     

A virgin flight across the Tasman Sea? Satellite tracking of post-fledging movement in the Australasian Gannet Morus serrator

New technologies enable tracking of the route, duration, and destination of previously unassessed long-distance movements. Fledgling Australasian Gannets Morus serrator from breeding populations in New Zealand had been reported to fly across the Tasman Sea to Australia, with this historic knowledge derived from the recovery of banded carcasses and from observations of initial flight direction. We deployed Argos satellite devices on ten M. serrator fledglings at Cape Kidnappers Gannetry, North Island, New Zealand, across 2 years. Birds that were tracked leaving the colony initially appeared to have landed on the sea. A male bird and two female birds were tracked moving along the east coast to the south tip of New Zealand. The two females then crossed the Tasman Sea to eastern Australian coastal waters in 4 and 5 days, respectively. We suggest that, contrary to historic reports, the route via Stewart Island constitutes a realized migration path for fledglings from Cape Kidnappers, which might minimize the distance traveled across the open sea to southeastern Australia or Tasmania. Our results further imply that initial direction of flight needs not be indicative of the subsequent migration route taken by M. serrator. This highlights the importance of direct tracking technology for adequate assessment of dispersal and migration in seabirds and other highly mobile species.     

PARTITIONING OF NESTING SPACE AMONG SEABIRDS OF THE BENGUELA UPWELLING REGION

Duffy, D. C. & La Cock, G. D. 1985. Partitioning of nesting space among seabirds of the Benguela upwelling region. Ostrich 56:186-201.

An examination of nesting habitats used by the four main species of seabirds nesting on southern African islands (Jackass Penguin Spheniscus demersus, Cape Cormorant Phalacrocorax capensis, Bank Cormorant P. neglectus and Cape Gannet Morus capensis) revealed relatively minor differences and extensive overlaps between species, primarily in subcolony size, steepness of nesting substratum, and proximity to cliffs. A weak dominance hierarchy existed; gannets could displace penguins, and penguins could displace cormorants. This hierarchy appeared to have little effect on partitioning of nesting space. Species successfully defended occupied sites in most cases of interspecific conflict, suggesting that site tenure by one species could prevent nesting by another. The creation of additional nesting space on Namibian nesting platforms did not increase guano harvests, suggesting that nesting space had not previously limited the total nesting population of Cape Cormorants, the most abundant of the breeding species, in Namibia.

While local shortages of nesting space may occur, populations of the four principal species of nesting seabirds in the Benguela upwelling region do not seem to have been limited by the availability of nesting space on islands.     

Population dynamics of Northern Gannets in North America, 1984–2009

Northern Gannet (Morus bassanus) colonies (N = 6) in North America have been regularly censused since the late‐1960s. Monitoring populations of a top‐predator like gannets provides insight into possible changes in the marine environment and contributes to an understanding of their demography. We report the results of aerial censuses of gannet colonies conducted from 1984 to 2009. Standard methods were used and involved making high‐quality photographs of colonies from a fixed‐wing aircraft, and subsequently counting apparently occupied sites (AOS) in the photographs. As of 2009, the breeding population of gannets in North America was estimated to be 116 825 pairs, or ～27% of the world population. From 1984 to 2009, the population grew at an average rate of 4.4% per annum and this growth was likely the result of continued population recovery after acute persecution in the past. Growth rates began to slow during the latter part of our study, likely due to density‐dependent effects and reductions in food availability. Despite the growth of the North American gannet population, gannets have not established new colonies, possibly because populations had been so depressed that growth could be accommodated within existing colonies.     

Capelatus prykei gen. et sp.n. (Coleoptera: Dytiscidae: Copelatinae) – a phylogenetically isolated diving beetle from the Western Cape of South Africa

Capelatus prykei gen. et sp.n. , a distinctive new lineage of copelatine diving beetle, is described from the greater Cape Town area of the Western Cape Province, South Africa, on the basis of both morphological and molecular data. The genus‐level phylogeny of Copelatinae is reconstructed using a combination of nuclear and mitochondrial DNA regions, demonstrating that Capelatus gen.n. has no close relatives within the Afrotropical region, instead forming a clade with the Palaearctic Liopterus and largely Australasian Exocelina. Capelatus gen.n. apparently represents a striking example of a phylogenetically isolated Cape lineage, which also appears to be narrowly endemic and endangered by ongoing habitat loss.     

DISPERSAL AND SITE FIDELITY OF CAPE GANNETS MORUS CAPENSIS

Klages, N. T. W. 1994. Dispersal and site fidelity of Cape Gannets Morus capensis. Ostrich 65:218-224.

Site fidelity and dispersal of juvenile and sexually mature adults was investigated at the largest southern African gannetry on Bird Island, Algoa Bay, where a minimum of 65000 airs occupy approximatel 2 ha at a mean density of 2,85 nests per m². Based on 512 ring recoveries and live retraps of known-aged birds of this colony, immature and non-breeding adult gannets dispersed widely along the coasts o Africa, reaching Maputo Bay (southern Mozambique) on the eastern side of the continent and the Namibian Skeleton Coast on the western side. Very few birds flew farther. There were conspicuously few ring recoveries at 400–500 km straight-line distance east from Bird Island, corresponding with the Pondoland coast in Transkei. A similar drop was observed in the west for the Tsitsikamma coast and the stretch of coast from Cape St. Blaize to Cape Infanta. In these regions reporting by members of the public is presumed to be low. either because the rocky coast is inaccessible or because of socioeconomic reasons. The geographical spread of the ring recoveries suggested a possible range contraction of the species between the 1950's and the period 1978–1993 but the nature of the data prevented a test of this hypothesis. No evidence was found that gannets from Bird Island breed or roost at other southern African colonies as a matter of habit. On the contrary, all survivors of post-fledgling dispersal eventually returned to their native colony, where they exhibited pronounced fidelity to the site where they hatched from the egg. Based on multiple retraps of 862 known-age individuals, 71.7 % of young adults took over vacant sites in the immediate vicinity of their original nest, 8,1% moved once but were faithful to their new site and in 20,2% of all cases faithfulness to the original site could not be shown. Moreover, in subsequent years edge birds did not vacate their sites to move towards the center, refuting the hypothesis that fringes are physically inferior breeding sites.     

Recognition of a species-poor, geographically restricted but morphologically diverse Cape lineage of diving beetles (Coleoptera: Dytiscidae: Hyphydrini)

Aim To establish the phylogeny and geographical origin of the genera of the diving beetle tribe Hyphydrini in order to investigate the origin of differences in geographical range size, intrageneric species‐richness and morphological disparity. In particular, we tested the hypothesis that the geographically restricted, species‐poor and morphologically deviating genera found in the Cape Region of South Africa are a paraphyletic pool of ‘primitive’ Hyphydrini, from which the morphologically more uniform, species‐rich and geographically widespread genera have originated. Location Worldwide, with special reference to the Cape Region of South Africa. Methods We constructed a genus‐level molecular phylogeny of 10 of the 14 known genera of Hyphydrini, including the five endemic to the Cape Region, using sequences from four gene fragments (two mitochondrial, rrnL and cox1; and two nuclear, 18S rRNA and histone 3, c. 2200 bp). Phylogenies were built with Bayesian methods, and linearized using penalized likelihood. Morphological disparity was characterized by correspondence analysis of a data matrix of 21 binary characters. We compare morphological disparity among groups using distance to the global and local centroids and the total range of morphospace occupied. Geographical range was estimated using the number of 6° longitude × 8° latitude Universal Transverse Mercator squares known to contain any species of each genus. Results Hyphydrini is made up of four well supported clades of similar relative genetic divergence: (1) Hyphydrus (Old World plus Australasia, 133 species), (2) the five endemic genera of the Cape Region, sister to Hovahydrus (Madagascar) (10 species), (3) Desmopachria (America, 92 species), and (4) two Oriental genera (Microdytes and Allopachria, 68 species). The morphological disparity within the Cape Region lineage has apparently increased with time, with the two genera closest to the global centroid paraphyletic and basal with respect to the three more recent, morphologically deviating genera. Differences in the number of species between each of the four lineages were not significant. The correlation between the number of species in each lineage and geographical range extent was highly significant, with the low species number of the Cape Region (six) well within the 95% confidence interval of the regression. Main conclusions Contrary to expectations, the species‐poor, morphologically deviating endemic genera of the Cape Region are not a ‘primitive’ relictual pool from which the widespread, species‐rich and morphologically uniform genera have originated. The morphological disparity within the Cape lineage has increased with time, and the apparent lack of species‐level diversification disappears when species–area relationships are considered. A major unanswered question is why one of the four main lineages of Hyphydrini has remained restricted to a very reduced area (the Cape Region), but despite this evolved the highest degree of morphological diversity seen in the tribe.     

At sea vocal repertoire of a foraging seabird

Seabirds spend most of their time at sea, yet our knowledge of their activities and behaviour is limited due to difficulties of in‐situ data collection. In particular, we know virtually nothing about their acoustic communication when at sea. We benefited from the recent development of miniaturised audio‐recording devices to deploy acoustic recorders on breeding Cape gannets Morus capensis to study their vocal activity while foraging. Call sequences were recorded on 1718 occasions, from which acoustic variables were measured on calls with good recording quality. A total of 1348 calls from 18 birds were measured in temporal and frequency domains. Each call was assigned to a behavioural context defined acoustically: sitting on the water, flying, taking off or just before diving. Potential discrimination among calls from different contexts was tested using the random forest algorithm. Within each context, individual stereotypy in the calls was assessed per acoustic variable using a measure of potential of individual coding, and as a combination of variables using a similar multivariate analysis. The acoustic structure differed according to the behavioural context (global accuracy of prediction 75%). Temporal variables (sequence and call duration) were most important to correctly classify the calls among the four contexts. When considering only two contexts, on the water and in the air (merging flying and diving), frequency and spectral variables (percentage of energy below 1200 Hz and fundamental frequency) were of most importance (accuracy 86%). A combination of acoustic variables was necessary to discriminate individuals, but calls from all contexts were not strongly individually distinct (accuracy 41–63%). We provided the first detailed acoustic analysis of a foraging seabird and demonstrated context‐specific acoustic structure in its vocalisations at sea. Our results suggest that seabirds use vocal communication to exchange various types of information that likely improves foraging success.     

Pentaschistis (Poaceae) diversity in the Cape mediterranean region: habitat heterogeneity and climate stability

Aim To evaluate the role of habitat heterogeneity on species richness and turnover in the mega species‐rich Cape Floristic Region (Cape), the mediterranean region of southern Africa. Location The Cape and Drakensberg regions of southern Africa. Methods Bioclimatic data were used to estimate habitat amount and habitat heterogeneity in the Cape and Drakensberg regions; these data were then used to explain the patterns of species diversity in the Pentaschistis clade (Poaceae) in these two regions. Habitat variables were used to create ‘bioclimatic units’ to characterize 1′× 1′ cells in southern Africa and to describe the niches of species. Using these bioclimatic units, the niche and range sizes of species in the two regions were compared. A phylogram was used to test for age and lineage effects. Results Pentaschistis species diversity and turnover are higher in the Cape than the Drakensberg. There is no significant difference in the habitat amount and heterogeneity between the two regions. Species occupy the same range of estimated niche sizes, yet there are significantly more range‐restricted Pentaschistis species in the Cape. Main conclusions The roles of age‐ and lineage‐related effects are rejected; biodiversity differences lie in the regions. Current macrohabitat does not explain the differences in biodiversity between the two regions. The larger number of range‐restricted species in the Cape cannot be explained by dispersal mechanism or the occupation of range‐restricted habitats. Species of Pentaschistis and other Cape clades share characteristics associated with species from historically climatically stable areas, and palaeoclimatic and palaeontological evidence indicates the Cape climate has been more stable than the Drakensberg climate throughout the Pleistocene. We conclude that the corresponding lack of extinction might have allowed an accumulation of species in the Cape. Similar climatic and biological evidence for the south‐west Australian Floristic and Mediterranean regions indicate that the same mechanism might explain the high species richness of these mediterranean regions.     

Individual differences in searching behaviour and spatial foraging consistency in a central place marine predator

Consistent intra‐population variability in foraging behaviour is found among a wide range of taxa. Such foraging specialisations are common among marine vertebrates, yet it is not clear how individuals repeatedly locate prey or foraging sites at ocean‐wide scales. Using GPS and time‐depth loggers we studied the fine‐scale foraging behaviour of central‐place northern gannets Morus bassanus at two large colonies. First, we estimated the degree of consistency in individual foraging routes and sites across repeated trips. Second, we tested for individual differences in searching behaviour in response to environmental covariates using reaction norms, estimated from mixed effect models. Adult gannets tracked over multiple foraging trips showed repeatable between‐individual differences in terminal points and departure angles of foraging trips, but low repeatability in trip duration and trip length. Importantly, individual birds showed highly repeatable dive locations, with consistently different environmental conditions (such as copepod abundance), suggesting a high degree of foraging site specialisation. Gannets also showed between‐individual differences in searching behaviour along environmental gradients, such that individuals intensified searching under different conditions. Together these results suggest that widespread individual foraging consistency may represent specialisation and be linked with individual responses to environmental conditions. Such divergent searching behaviour could provide a mechanism by which consistent foraging behaviour arises and is maintained among animals that forage across large spatial scales.     

PREDATION AND KLEPTOPARASITISM BY SKUAS IN A SHETLAND SEABIRD COLONY

Feeding methods and relations of Great Skuas and Arctic Skuas to prey were studied in a seabird colony at Hermaness, Shetland. Great Skuas obtained food by kleptoparasitism, predation and scavenging. They induced Gannets to regurgitate by interfering with their flight; grasping the Gannet by the wing or tail or pushing it down with the feet on its back. Gannets tried to escape by descending to the surface, and regurgitated during 12% of the chases, most frequently when pursued by several birds. Great Skuas caught Puffins by swooping at flocks in the colony. Puffins flying with fish to their young were also chased, releasing food on one fifth of the attacks, or escaping down to the sea and diving. Great Skuas also took Kittiwake nestlings by hovering and grasping the chick with the bill, killing and eating it on the surface. Adult Kittiwakes from nearby nests took to the air, mobbing the predator. More Kittiwakes were engaged in mobbing at unsuccessful than at successful predation attempts, indicating that colonial breeding may be of selective value under such predation. Two different estimates pointed to a Kittiwake nestling predation of 0–12 and 014 young per pair. Fledging success of Kittiwakes was estimated at 0–87-1-06 young per pair, considerably lower than at English colonies where predators are absent. In spite of the predation, the Kittiwake colony showed no signs of decrease. Agonistic behaviour and other evidence indicate that Great Skuas defend feeding territories at the seabird colony. Skuas, gulls and Fulmars competed for food at carcasses. Fulmars dominated and chased away skuas. Arctic Skuas deprived Puffins of food. They patrolled the cliff, intercepting Puffins arriving with fish, snatching it from their victim's bill, or inducing them to release fish. Puffins continuing their inward flight lost food more often (30%) than birds descending to the sea (15%)—sometimes diving below. This opportunity to escape may explain the lower success of skuas at Hermaness than at a Puffin colony farther inland from the shore (Grant 1971). Other factors being equal, proximity to the sea may thus reduce the risk of kleptoparasitism.     

Evidence from genetic and Lagrangian drifter data for transatlantic transport of small juvenile green turtles

Aim A key life‐history component for many animals is the need for movement between different geographical locations at particular times. Green turtle (Chelonia mydas) hatchlings disperse from their natal location to spend an early pelagic stage in the ocean, followed by a neritic stage where small juveniles settle in coastal areas. In this study, we combined genetic and Lagrangian drifter data to investigate the connectivity between natal and foraging locations. In particular we focus on the evidence for transatlantic transport. Location Atlantic Ocean. Methods We used mitochondrial DNA (mtDNA) sequences (n = 1567) from foraging groups (n = 8) and nesting populations (n = 12) on both sides of the Atlantic. Genetic data were obtained for Cape Verde juvenile turtles, a foraging group not previously sampled for genetic study. Various statistical methods were used to explore spatial genetics and population genetic structure (e.g. exact tests of differentiation, Geneland and analysis of molecular variance). Many‐to‐many mixed stock analysis estimated the connectivity between nesting and foraging groups. Results Our key new finding is robust evidence for connectivity between a nesting population on the South American coast (25% of the Surinam nesting population are estimated to go to Cape Verde) and a foraging group off the coast of West Africa (38% of Cape Verde juveniles are estimated to originate from Surinam), thus extending the results of previous investigations by confirming that there is substantial transatlantic dispersal in both directions. Lagrangian drifter data demonstrated that transport by drift across the Atlantic within a few years is possible. Main conclusions Small juvenile green turtles seem capable of dispersing extensively, and can drop out of the pelagic phase on a transatlantic scale (the average distance between natal and foraging locations was 3048 km). Nevertheless, we also find support for the ‘closest‐to‐home’ hypothesis in that the degree of contribution from a nesting population to a foraging group is correlated with proximity. Larger‐sized turtles appear to feed closer to their natal breeding grounds (the average distance was 1133 km), indicating that those that have been initially transported to far‐flung foraging grounds may still be able to move nearer to home as they grow larger.