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Sex-specific foraging behaviour may lead to differences between the sexes in both resource acquisition and exposure to threats and thereby contribute to sex-specific reproductive roles or mortality. As such, it is important to identify in which species sex-specific foraging behaviour occurs. We deployed GPS devices to incubating common terns (Sterna hirundo) from a German breeding population to study how sex and spatial or temporal extrinsic factors influence the daily activity budget, foraging distribution, and trip characteristics of this slightly sexually size dimorphic seabird. Birds of both sexes only foraged during the day, showing peaks of activity after sunrise and before sunset, perhaps in response to temporal variation in prey availability and/or as a strategy to overcome or prepare for nocturnal fasting. Furthermore, foraging was more frequent around low tide and at the beginning of the flood tide and mainly occurred in shallow (< 5 m depth) and coastal waters (< 2 km from coastline) up to 20 km from the colony. Females rested less, foraged closer to the colony in more coastal waters, and showed a lower maximum flight speed than males. Males foraged more outside protected areas than females and showed higher variability in their foraging distribution throughout the tide cycle. As such, our study provides evidence for sex-specific aspects of foraging behaviour in common terns and underlines the importance of considering sex-specific foraging distributions when assessing the impact of at-sea threats on seabirds, knowledge of which should be incorporated when developing conservation management strategies., Author(s): Teresa Militão [sup.1] [sup.2] , Nathalie Kürten [sup.1] , Sandra Bouwhuis [sup.1] Author Affiliations: (1) https://ror.org/0309m1r07, grid.461686.b, 0000 0001 2184 5975, Institute of Avian Research, , An der Vogelwarte [...]

ABSTRACT. We studied movement rates and the general flight behavior of bird flocks seen on radar and recorded visually at Northstar Island, Arctic Alaska, from 13 to 27 September 2002. [...]

Competition is thought to play a fundamental role in structuring avian communities, yet this has been difficult to quantify and demonstrate in marine ecosystems. We tested for fine-scale competition over foraging space between sympatric pursuit-diving seabirds, Marbled Murrelet (Brachyramphus marmoratus (J.F. Gmelin, 1789)) and Common Murre (Uria aalge (Pontoppidan, 1763)). We simultaneous assessed the effects of inter- and intra-specific competition among these predators, predicting that the larger Common Murres would out-compete the smaller Marbled Murrelets for foraging space. A theodolite was used to map the fine-scale (±2 m) distributions of birds on the water; distance from shore measurements and nearest-neighbour spatial statistics quantified the spatial overlap and segregation between species. Species distributions differed with respect to distance from shore, but overlapped extensively within 1200 m of the shoreline. Nearest-neighbour statistics, assessed with randomization tests, showed Marbled Murrelets foraging farther from Common Murres (mean distances 294 m) than from other Marbled Murrelets (95 m), but groups of Common Murres foraged with similar spacing among conspecifics (266 m) and competitors (186 m). These results suggest avoidance of Common Murres by Marbled Murrelets (interspecific competition) but intraspecifc competition among Common Murres. Avoidance behaviour may minimize the impacts of aggression or competition, but by avoiding Common Murres, the Marbled Murrelets may also be reducing their foraging opportunities. On croit que la competition joue un role fondamental dans la structuration des communautes d'oiseaux, bien qu'il soit difficile de le mesurer et le demontrer dans les ecosystemes marins. Nous avons verifie a echelle fine l'existence de competition pour l'espace de recherche de nourriture chez des oiseaux de mer sympatriques qui font de la plongee de poursuite, le guillemot marbre (Brachyramphus marmoratus (Gmelin, 1789)) et le guillemot marmette (Uria aalge (Pontoppidan, 1763)). Nous avons mesure simultanement les effets de la competition inter- et intra-specifique entre ces predateurs et avons predit que l'espece la plus grande, le guillemot marmette, gagnerait la competition pour l'espace de recherche de nourriture contre le guillemot marbre plus petit. Nous avons cartographie a l' aide d' un theodolite les repartitions a echelle fine (± 2 m) des oiseaux sur l' eau; les distances de la rive et des methodes statistiques basees sur le plus proche voisin ont permis de determiner le chevauchement spatial et la segregation entre les especes. Les repartitions des especes varient en fonction de distance de la rive et se chevauchent considerablement sur les premiers 1200 m a partir de la ligne du rivage. Les statistiques basees sur le plus proche voisin, evaluees par des tests de randomisation, montrent les guillemots marbres s'alimentant plus loin des guillemots marmettes (distance moyenne de 294 m) que des autres guillemots marbres (95 m); cependant, les guillemots marmettes recherchent leur nourriture en maintenant un espacement semblable avec les autres guillemots marmettes (266 m) et avec leurs competiteurs (186 m). Ces resultats indiquent que les guillemots marbres evitent les guillemots marmettes (competition interspecifique), mais qu'il existe une competition intraspecifique entre les guillemots marmettes. Ce comportement d' evitement peut reduire les impacts de l' agression et de la competition, mais, en evitant les guillemots marmettes, les guillemots marbres reduisent peut-etre aussi leurs occasions de se nourrir. [Traduit par la Redaction], Introduction Competition is thought to play a fundamental role in structuring avian communities (MacArthur 1958; Cody 1974; Schoener 1982; Lovette and Hochachka 2006). Nevertheless, mechanisms for competition remain unknown in [...]

Streaked Shearwaters (Calonectris leucomelas) breed in temperate regions of East and Southeast Asia and have been thought to migrate to tropical regions near the Equator after breeding. We documented the migratory and foraging behavior of this species using global location sensors (GLS). The GLS loggers were attached to 48 breeding birds in 2006 and were subsequently recovered from 38 birds in the following year. The Streaked Shearwaters migrated from the seas around Japan to three wintering areas in the tropics, the seas off northern New Guinea, the Arafura Sea, and the South China Sea (4,000, 5,400, and 3,500 km from the breeding colony, respectively). Most Streaked Shearwaters wintered off northern New Guinea, an area of low primary productivity but high Skipjack Tuna (Katsuwonus pelamis) abundance. Streaked Shearwaters flew for longer periods and landed on the water more frequently around dawn and dusk during the wintering period. This pattern of activity is similar to that of subsurface predators such as tuna, and to that of tropical seabirds that are known to feed with subsurface predators. We suggest that Streaked Shearwaters probably forage in association with subsurface predators in the tropical oceans during the wintering period. Foraging in association with subsurface predators and morphological adaptations for gliding may allow Streaked Shearwaters to forage efficiently in both temperate and tropical environments. Received 9 February 2010, accepted 3 July 2010. Key words: activity, Calonectris leucomelas, migrate, seabird, Streaked Shearwater, subsurface predators, tropical, winter. Calonectris leucomelas cria en regiones templadas del este y sudeste de Asia y se ha pensado que los individuos migran a regiones tropicales cerca del Ecuador despues de reproducirse. Documentamos el comportamiento migratorio y de forrajeo de esta especie usando sensores de localizacion global (GLS, por sus siglas en ingles). Los dispositivos GLS se acoplaron a 48 aves reproductoras en 2006 y fueron recuperados de 38 aves en el ano siguiente. Las aves migraron de los mares alrededor de Japon a tres areas de invernada en el tropico: los mares de la costa del norte de Nueva Guinea, el mar Arafura y el mar del sur de China (a 4000, 5400 y 3500 km de la colonia de reproduccion, respectivamente). La mayoria de los individuos pasaron el invierno ai norte de Nueva Guinea, un area con baja productividad primaria pero con alta abundancia del atun Katsuwonus pelamis. Las aves volaron por periodos mas largos y aterrizaron en el agua mas frecuentemente alrededor dei alba y del ocaso durante el periodo de invernada. Este patron de actividad es similar al de depredadores que se alimentan bajo la superficie, como el atun, y al de aves marinas tropicales que se alimentan junto con depredadores bajo la superficie. Sugerimos que C. leucomelas probablemente forrajea en asociacion con depredadores bajo la superficie en los oceanos tropicales durante el periodo de invernada. Esta asociacion y las adaptaciones morfologicas para planear podrian permitir que estas aves forrajeen eficientemente en ambientes tanto templados como tropicales. DOI: 10.1525/auk.2010.10029

Offspring provisioning constrains the foraging behavior of breeding seabirds temporally and spatially. In species whose foraging grounds overlap with commercial fisheries, quantifying the provisioning behavior of breeding adults throughout the season can illuminate the nature of interactions with the fisheries and, where seabird bycatch exists, contribute to development of mitigation measures. In 2004-2005, we studied the provisioning behavior of Flesh-footed Shearwaters (Puffinus carneipes) on Lord Howe Island, Australia, using the repeated-weighing technique. Specifically, we determined (1) meal size, feeding frequency, and chick growth rates; (2) attendance behavior of adults; and (3) estimated food consumption at the individual and colony levels. Incubation shift duration averaged 9.5 [+ or -] 1.6 (SD) days. Foraging-trip duration was bimodal, with both short trips ([less than or equal to]3 days) and long trips (>3 days) recorded. Average meal mass was greater during the late chick-rearing period and was not influenced by the time interval between meals. Developing chicks had a food conversion efficiency of 27%, with a total individual food requirement of 2,337 g to fledge successfully. An increase in the interval between provisioning events from the early to the late chick-rearing period was associated with significantly more long foraging trips by parent birds; however, there was no variation in the proportion of study birds that returned each night. Received 2 September 2008, accepted 19 May 2009. Key words: chick provisioning, Flesh-footed Shearwater, growth rates, Puffinus carneipes, resource allocation, seabird foraging. El aprovisionamiento de las crias restringe temporal y espacialmente el comportamiento de forrajeo de las aves en la epoca reproductiva. En especies cuyas areas de forrajeo se superponen con pesquerias comerciales, cuantificar el comportamiento de aprovisionamiento de las aves reproductivas a lo largo de la temporada podria dar luces sobre la naturaleza de las interacciones con las pesquerias y, donde existen capturas no intencionales de aves marinas, podria contribuir al desarrollo de medidas de mitigacion. Utilizando la tecnica de pesado repetido, estudiamos el comportamiento de aprovisionamiento de Puffinus carneipes en la isla Lord Howe, Australia, entre 2004 y 2005. Especificamente, determinamos (1) el tamano de las meriendas, la frecuencia de alimentacion y la tasa de crecimiento de los pichones; (2) el comportamiento de atencion del nido por parte de los adultos; y (3) estimados del consumo de alimento a nivel de los individuos y de la colonia. Los turnos de incubacion tuvieron una duracion promedio de 9.5 [+ or -] 1.6 (DE) dias. La duracion de los viajes de forrajeo fue bimodal, existiendo tanto viajes cortos ([less than or equal to]3 dias) como largos (>3 dias). El peso promedio de las meriendas fue mayor durante la fase tardia del periodo de cria de pichones y no fue influenciado por el intervalo de tiempo transcurrido entre meriendas. Los pichones en desarrollo presentaron una eficiencia de conversion del 27% y un requerimiento total de alimento de 2337 g para emplumar exitosamente. Un incremento en el intervalo entre eventos de aprovisionamiento observado entre la parte inicial y la parte final del periodo de cria de pichones estuvo asociado con viajes de forrajeo significativamente mas largos por parte de los padres. Sin embargo, no existio variacion en la proporcion de aves de estudio que regresaron cada noche. DOI: 10.1525/auk.2009.09158

Satellite transmitters and geographic-positioning-system devices often add substantial mass to birds to which they are attached. Studies on the effects of such instruments have focused on indirect measures, whereas the direct influence of extra mass on pelagic behavior is poorly known. We used 2.5-g geolocators to investigate the effect of extra mass on the pelagic behavior of Cory's Shearwaters (Calonectris diomedea) by comparing the traits of a single foraging trip among a group carrying 30-g weights, a group carrying 60-g weights, and a control group. The weights were attached to the birds' backs using typical techniques for attaching satellite transmitters to seabirds. The extra mass increased the duration of the birds' trips and decreased their foraging efficiency and mass gained at sea. These indirect effects may be related to foraging traits: weighted birds showed a greater search effort than control birds, traveled greater distances, covered a greater foraging area, and increased the maximum foraging range. Furthermore, the time spent on the sea surface at night was greater for weighted than for control groups, which showed that the extra mass also affected activity patterns. Our results underline the need to quantify the effects of monitoring equipment commonly used to study the pelagic behavior of seabirds. We suggest that geolocators can be used to obtain control data on foraging-trip movements and activity patterns. Received 21 December 2008, accepted 20 August 2009. Key words: at-sea activity, Calonectris diomedea, Cory's Shearwater, foraging strategies, geolocators. Los transmisores satelitales y los aparatos con sistemas de posicionamiento geografico frecuentemente agregan un peso substancial a las aves a las que se los sujetan. Los estudios sobre los efectos de estos instrumentos se han enfocado en medidas indirectas, mientras que la influencia directa del peso extra en el comportamiento pelagico es poco conocida. Empleamos localizadores geograficos de 2.5 g para investigar el efecto del peso extra sobre el comportamiento pelagico de Calonectris diomedea mediante la comparacion de los rasgos de un unico viaje de forrajeo entre un grupo de aves que portaba pesos de 30 g, un grupo que portaba pesos de 60 g y un grupo control. Los pesos fueron colocados sobre la espalda de las aves usando las tecnicas tipicas para sujetar los transmisores satelitales a las aves marinas. El peso extra incremento la duracion de los viajes de las aves y disminuyo su eficiencia de forrajeo y el peso corporal adquirido en el mar. Estos efectos indirectos pueden estar relacionados con los rasgos de forrajeo: las aves con pesos suplementarios mostraron un esfuerzo de busqueda mayor que las aves control, viajaron distancias mas grandes, cubrieron un area de forrajeo mayor e incrementaron el ambito maximo de forrajeo. Mas aun, el tiempo pasado sobre la superficie del mar durante la noche fue mayor para los grupos con peso suplementario que para los grupos control, lo que mostro que el peso suplementario tambien afecto los patrones de actividad. Nuestros resultados destacan la necesidad de cuantificar los efectos del equipo de monitoreo usado comunmente para estudiar el comportamiento pelagico de las aves marinas. Sugerimos que los localizadores geograficos pueden ser usados para obtener datos de control de los movimientos de los viajes de forrajeo y de los patrones de actividad. DOI: 10.1525/auk.2009.09036

Breeding seabirds are extreme central-place foragers, commuting long distances between colonies and feeding areas. Central-place foraging theory predicts that prey items close to the colony will be preferred over prey items distant from the colony, which can lead to prey depletion near the colony ('Storer-Ashmole's halo'). To investigate the relevance of these ideas to a single-prey loader, we equipped chick-rearing Thick-billed Murres (Uria lomvia) with time--depth recorders (1999-2007) and monitored prey deliveries (1993-2008). Because feeding rates were constant for chicks 3-15 days old, we restricted analyses to that age group. Between-date relationships were examined within individuals to avoid confounding effects of specialization and parental quality. The mass of prey items increased with foraging [distance.sup.0.5], which suggests that large prey items were depleted by foraging pressure. Foraging distance for pelagic species increased through the season in years without spawning. After accounting for bathymetry, foraging effort decreased with distance from the colony for benthic fish and, in years without spawning, for pelagic fish. Within each season, Thick-billed Murres 'fished down the food web'; they began by feeding on large fish, progressed to medium-sized prey (small fish), and finished feeding on small prey (invertebrates). We concluded that pelagic species responded to seabird foraging pressure by moving away from the colony, creating a three-dimensional halo. Benthic species, meanwhile, were depleted from a nearby shelf but remained abundant at a more distant offshore bench. We suggest that populations of central-place foragers are partially regulated by prey depletion. Key words: central-place foraging, food-web structure, Hudson Bay, resource depletion, Thick-billed Murre, top-down forcing, Uria lomvia.

Intense El Nino events severely impact seabird populations, often months in advance of peak temperature anomalies. The trophic mechanisms responsible for these impacts ate unknown but ate assumed to operate at seasonal scales and to be linked to ocean productivity changes. Precursors to El Nino events include changes in both sea-surface temperature and the depth of the 20[degrees]C thermocline. Foraging piscivorous seabirds are known to be sensitive to both thermocline depth and sea-surface temperature change, but the potential influence of these phenomena on breeding dynamics is unknown. Using 18 years of data on three seabirds of the western tropical Pacific, we show that pelagic seabird breeding participation is directly and independently related to changes in both surface chlorophyll concentration and thermocline depth that occur well in advance of El Nino generated sea-surface temperature anomalies. In contrast, breeding in an inshore foraging species is not correlated with any environmental/biological parameters investigated. These findings demonstrate that El Nino related phenomena do not affect seabird prey dynamics solely via productivity shifts at seasonal scales, nor in similar ways across different seabird foraging guilds. Our results also suggest that population declines observed in the western tropical Pacific may be directly related to the frequency and intensity of El Nino anomalies over the study period. Key words: 20[degrees]C thermocline; Anous stolidus; breeding participation; El Nino Southern Oscillation; Great Barrier Reef, Australia; precursor impacts; productivity; Sterna bergii; Sterna fuscata; western tropical Pacific.

Systematic monitoring of seabird populations in Canada has been ongoing since the 1920s and the monitoring of diets and other biological indicators of ecosystem change started in the 1970s. Long-term monitoring of population parameters began in the 1980s. These studies originally were conducted mainly by the Canadian Wildlife Service, but subsequently have involved several universities and nongovernment organization groups. We review the results of this monitoring from the 1970s onwards for six oceanographic regions to assess population trends among Canadian seabirds and correlated trends in diets, phenology, and other breeding biology variables. Within regions, trends in most variables studied have been broadly congruent, but there was often variation among regions. In particular, seabird populations in the Pacific coast zone affected by the California Current upwelling system have shown generally negative trends since the 1980s, whereas trends for populations of the same species to the north of this zone have been mainly positive. Likewise, on the east coast, trends at Arctic colonies have been decoupled from those at colonies around Newfoundland and in the Gulf of St. Lawrence, especially since the major cold water event of the early 1990s. Several long-term studies have shown an association between population events and diet and phenology changes. Diet and indicators of condition (chick growth, reproductive success) sometimes responded very rapidly to oceanic changes, making them excellent signals of ecosystem perturbations. The review highlights the effects of decadal-scale regime shifts on Canadian seabirds, confirms the value of long-term studies and supports the applicability of single-site observations to regional populations. Key words: seabirds, Canada, oceanography, population trends, environmental monitoring, regime shift, indicators. Au Canada, le suivi systemalique des populations d'oiseaux marins s'effeclue depuis les annees 1920 et le suivi des dietes el autres indicateurs biologiques de changement des ecosysiemes, depuis les annees 1970. Le suivi a long lerme des parametres des populations a debute dans les annees 1980. Ces etudes ont ete conduites au depart par le Service canadien de la faune, mais subsequemment ont implique plusieurs universites et groupes d'organisations non gouvernementales. Les auteurs passent en revue les result ats de ces suivis a partir des annees 1970 en continu pour six regions geographiques, afin d'evaluer les tendances des populations chez les oiseaux marins canadiens et faire des correlations avec les dietes, la phenologie et autres variables de la biologie de l'accouplement. Dans les regions, les tendances pour la plupart des variables etudiees se sont averees largement congrues, mais on observe souvent une variation entre les regions. Particulierement, les populations d'oiseaux marins de la zone cotiere du Pacifique, affectees par le systems de derive du courant de Californie, montrent des tendances generalement negatives depuis les annees 1980, alors que les tendances pour les populations des memes espeees au nord de cette zone se sont averees generalement positives. De la meme facon, sur la cote est, on observe des tendances vers un decouplage des colonies arctiqnes par rapport aux colonies de Terre-Nenve et du golfe St-Laurent, stirtotit depuis l'arrivee majeure d'eau froide dans les annees 1990. Plusieurs etudes a long terme ont montre tine association entre les evenements dans les populations et les changements de diete et de phenologie. La diete et les indicateurs de conditions (croissance des jeunes, succes de la reproduction) reagissent quelques fois tres rapidement aux changements oceaniques. ce qui en fait d'excellents signaux de perturbation des ecosystemes. Cette revue souligne les effete des changements de regime a l'echelle des decades chez les oiseaux de mer canadiens, confirme l'interet des etudes a long terme et supporte l'applicability d'observations sur des sites individuels aux populations regionales. Mots-des : oiseaux marins, Canada, oceanographie, tendances des populations, suivis environnementaux, changements de regime, indicateurs. [Traduit par la Redaction], Introduction Tracking bird populations to monitor environmental change has frequently been advocated (Furness and Greenwood 1993). Because of the expense and technical difficulty of sampling marine resources, especially offshore, seabirds [...]

The Red-footed Booby (Sula sula) is considered one of the most polymorphic seabirds, with three adult plumage types recognized: white, white-tailed brown, and brown, as well as several degrees of intermediates. Here we show that there is no evidence of deviation from random mating according to plumage color in the largest population of Red-footed Boobies in the Galapagos Archipelago, based on a random sample of approximately 300 pairs, which agrees with previous results found in the Indian Ocean. We also found that the ratio of color morphs varies among islands within this archipelago, with the populations of Islas Genovesa and Wolf presenting a reversed ratio (90% brown, and 10% white) when compared to the majority of Red-footed Boobies populations worldwide. Furthermore, there was no indication of differential habitat association among morphs. We concluded that plumage color does not play an important role in mate choice, and as a result, nonrandom mating based on plumage color is likely not a selective mechanism maintaining the plumage polymorphism in this population. Key words: Galapagos Archipelago, habitat selection, nonrandom mating, plumage polymorphism, Sula sula, Sulidae. Sula sula e considerada uma das especies mais polimorficas de aves marinhas, com tres padroes de plumagem reconhecidos: branco, marrom-de-rabo-branco e marrom, alem de varios graus de intemediarios. Nesse estudo, nos mostramos que nao ha evidencias de desvios do padrao de pareamento randomico baseado na coloracao da plumagem na maior populacao de Sula sula no arquipelago de Galapagos, baseado em uma amostragem randomica de aproximadamente 300 pares. Tambem mostramos que a proporcao de individuos com padroes de plumagem diferentes varia entre ilhas no arquipelago de Galapagos, com as populacoes das Ilhas Genovesa e Wolf apresentando proporcao inversa daquela encontrada na maioria das populacoes de Sula sula ao longo da area de distribuicao da especie (90% marrom e 10% branco). Alem disso, nao encontramos nenhuma indicacao de associacoes diferenciadas de habitat entre individuos de diferentes padroes de plumagem. Concluimos que a coloracao da plumagem nao e de importancia para a escolha de parceiros sexuais, e como resultado, o processo de pareamentos naorandomico baseado na coloracao da plumagem possivelmente nao funciona como mecanismo de manutencao do polimorfismo nessa populacao.

Abstract: In the North Sea, the lesser sandeel (Ammodytes marinus) is the target of an industrial fishery and the principal prey of many top predators. Because of concerns about potential [...]

We investigated the foraging habitats of the winter breeding community of tropical seabirds from Europa Island (Mozambique Channel) in September 2003. We focused our study on the dominant species of this austral community, the sooty tern (Sterna fuscata), the red-footed booby (Sula sula), and the frigatebirds, including the great (Fregata minor) and the lesser frigatebirds (F. ariel). We considered the at-sea distribution and abundance of these species in relation to chlorophyll concentration, sea-surface temperatures, sea-surface height anomalies, depth of the thermocline, distance to the colony, and presence of surface marine predators, flying fishes and other seabirds. Although the marine environment where seabirds foraged was oligotrophic, it presents the best feeding opportunities for seabirds for the area in winter. Our study demonstrates that the winter-breeding seabird species of Europa Island tend to forage in productive waters in association with other marine predators when possible. Sooty terns and frigatebirds were widely distributed in the whole study area, whereas red-footed boobies were not found farther than 160 km from their colonies and were associated with relatively productive waters. Sooty terns and red-footed boobies were aggregated where flying fishes were abundant. The presence of other marine predators was associated with larger multispecies feeding flocks than when no association occurred. Sooty terns, which are numerically dominant at Europa and adopted network foraging, seem to be catalysts of feeding events, and represented a good target for the other foraging species, especially frigatebirds. However, when possible, frigatebirds favour association with flocks of red-footed boobies., Introduction Oceanic seabirds have to cope with major constraints when breeding, which are spatial and temporal changes in prey distribution, and the necessity to commute from feeding to breeding areas [...]

We investigated a link between facultative semelparity ('male die-off') in a small, endangered marsupial, Parantechinus apicalis (the dibbler), and the availability of resources on two small islands in Western Australia. Post-mating survival of male dibblers differed between the two islands, and the input of nutrients from nesting seabirds was a possible factor affecting available resources and therefore survival of male dibblers. Seabirds can increase significantly the concentration of nutrients in the soil and can ultimately lead to an increase in abundance of primary consumers and predators. We compared concentrations of soil nutrients, body condition, and post-mating survival of male dibblers on both islands. The body condition and post-breeding survival were significantly better on the island with many seabirds, where soil nutrients were up to 18 times higher, than on the adjacent island with fewer seabirds. Our results indicate a potential link between male die-off and resource availability. We suggest that marine-derived nutrients transported onto islands by nesting seabirds can alter the productivity as well as the life history traits of species in an island ecosystem. Key words: body condition; dasyurid; dibbler; male die-off; nutrients; Parantechinus apicalis; seabirds; semelparity; Western Australia.

Low spatiotemporal variability in the abundance of nonschooling prey might allow Pigeon Guillemots (Cepphus columba) to maintain the high chick provisioning rates that are characteristic of the species. We tested predictions of this hypothesis with data collected with beach seines and scuba and hydroacoustic surveys in Kachemak Bay, Alaska, during 1996-1999. Coefficients of variability were 20-211% greater for schooling than nonschooling prey on day, seasonal, and km scales. However, the proportion of schooling prey in chick diets explained relatively little variability in Pigeon Guillemot meal delivery rates at the scale of hours ([r.sup.2] = 0.07) and weeks ([r.sup.2] = 0.19). Behavioral adaptations such as flexible time budgets likely ameliorate the negative effects of high resource variability, but we propose that these adaptations are only effective when schooling prey are available at distances well below the maximum foraging range of the species. Key words: Cepphus, demersal, foraging, pelagic, provisioning, quality-variability trade-off, seabirds.

Eleonora's Falcon (Falco eleonorae) breeds in the Mediterranean region and is highly adapted for catching small birds on passage migration between Eurasia and their African winter quarters, which they feed their young. We studied gliding flight behavior of Eleonora's Falcon at a breeding colony located on a small island southwest of Sardinia, Italy. Gliding and soaring flight performance was measured using an optical range finder and evaluated against flight mechanical theory. The male falcon does the majority of hunting and usually sets off from the colony to hunting areas located at high altitude over the open sea to catch prey. To lower the cost of transport and maximize the energy gain from hunting, we show that the birds use vertical winds for soaring when available. The occurrence of rising air changes with wind direction. At north-north-westerly winds (on-shore), slope lift is available outside the nesting cliffs, and at south-southeasterly winds thermals that form over the island drift out over the sea. Our observations demonstrated the flexibility of flight behavior in relation to the wind situation, and birds thereby make full use of available soaring conditions.

We studied patterns of parental care in Crested Auklets (Aethia cristatella), a monogamous seabird, for three breeding seasons (1996-1998) in the Aleutian Islands, Alaska, using radio-telemetry. In 1996, we found no sexual differences in parental care, low breeding site attendance rates, and reduced occurrences of copepods in food samples delivered to chicks, suggesting that food availability may have been low. In 1997 and 1998, we found significant differences in parental care between males and females, particularly early in the chick-rearing period: males attended and brooded their single chick 75% and 90% longer than females, while females provisioned 33% and 36% more often than males, respectively. We also found significant differences between prey types delivered to chicks by males and females for these two years. Males brought in 30% more euphausiids, a relatively large pelagic crustacean, than females, whereas females brought in 36% more copepods, a smaller crustacean, than males; however, prey mass per load did not differ. In 1998, we experimentally measured how vulnerable unattended young chicks were using models placed in unoccupied crevices. Eighty-three percent of the models showed signs of attack, presumably by conspecific adults. We concluded that unattended Crested Auklet chicks are highly vulnerable to attack. We suggest that males took on a greater role in chick brooding than their mates because they have a larger and more strongly hooked bill and are more aggressive than females, and thus better equipped than females to guard young chicks or the crevice breeding site. Key words: Aethia cristatella, Crested Auklet, euphausiids, parental care, planktivore, seabird.

We observed a male Razorbill (Alca torda) residing among a group of breeding Common Murres (Uria aalge) on Great Island, Newfoundland, during 1996-2000. Behavioral observations indicated that the presence of the Razorbill directly contributed to the break-up of one pair of murres and prevented another pair from producing an egg. In addition, murres with sites close to the Razorbill site may have experienced increased energetic demands arising from aggressive interactions frequently initiated by the Razorbill. A consequence of the presence of a heterospecific resident in a seabird colony may be decreased reproductive success for individuals breeding nearby., The known incidence of intergeneric hybridization among seabirds is low (Grant and Grant 1992). However, there are anecdotal reports of individuals from one species living among and socially interacting with [...]

Research indicates that Cassin's Auklet nestlings resulting from late-breeding parents do not have the same growth rate as nestlings resulting from early-breeding parents. Theories include that early-breeding parents are of higher genetic quality and are able to forage better than late-breeders, and that seasonal declines in food supply affect late-bred nestlings more than early-bred ones.

Research concerning the importance of the California Current system to marine bird populations is presented. The correlation between population and warm fronts suggests that marine birds are able to detect areas of upwelling.

Maximum depth recorders were fitted on Dovekies of northwestern Greenland to measure variations in diving depths. The average maximum dive depth was calculated at nearly 28 meters, with few birds diving to 34.7 meters, the deepest depth recorded.

A new study investigates the distribution and activities of Steller's Eiders wintering on a shallow lagoon and a deep-water embayment along the Alaska Peninsula between September 1980 and May 1981. The study shows that during the remigial molt, birds were seen on the lagoon but not on the bay. However, eiders used both sites following completion of molt, although their use of the lagoon was restricted in severe weather. The dominating foraging strategy was synchronous diving.

Little is known about the distribution of Marbled Murrelets during the nonbreeding season, but the use of marked individuals makes it possible to relate specific breeding populations with wintering populations. A murrelet banded during the breeding season in 1995 at Theodosia Inlet, BC, was recaptured during the fall of 1996 near Orcas Island, Washington State, some 220 km away from the original banding location. It was again captured during the summer of 1997 at Theodosia Inlet. The study suggests that both migratory and nonmigratory individuals can be found within a single summering population.

A new study examines the wing morphology of nine species of seabird in the tropical Pacific to investigate the theory that wing morphology reflects ecological differences in searching for and catching prey. It is shown that foraging differences among species correlated with predicted differences in wing morphology.

Most studies of kin recognition in birds have examined parent-offspring recognition and few have focused on individual sibling recognition. A new study of common tern chicks investigates the development of sibling recognition. The study shows that sibling determination among common tern chicks develops as early as 4-days-old.

Discard consumption by seabirds in the North Sea are measured through experiments on board fishery research ships. Potential biases in this technique were investigated, although discard techniques vary considerably between commercial fishing fleets, seasons and areas. Findings showed that while the total usage of discards remained unaffected by the various phases of the fish catch process, the length of fish discarded, the various methods of gathering the data and the quantities of fish discarded at once all substantially affect the results.

The presence of pursuit-diving seabirds positively affects the duration of feeding flocks. Mechanisms that keep prey close to the surface near shore may differ from mechanisms used in the open ocean. These were gleaned from an investigation of the species composition, frequency, distance offshore and duration of multispecies seabird feeding flocks in the Galapagos Islands, Ecuador. Findings showed that pursuit divers such as Galapagos Penguins and Flightless Comorants increase the flocks' longevity.

A new study investigates the diving performances of two tropical plunge-diving pelecaniformes, the red-footed booby and the red-tailed tropicbird. The study, conducted off the coast of Mozambique, uses maximum depth recorders fitted to breeding adults. It is shown that both species mainly use the first four mt of water, reached by passive plunge diving, although birds are thought to use feet and/or wings to actively swim underwater to achieve a range of depths, up to 9.6 mt.