History, Status, and Taxonomic Identity of Caribou (Rangifer tarandus) in Northwest Greenland

Historical references indicate that caribou (Rangifer tarandus L.) numbers drastically declined throughout the Thule District during the early part of this century, and that the primary causes were: (1) the influx of polar explorers and their distribution of firearms to the Thule Eskimos which initiated extensive hunting pressure on caribou; and (2) a series of relatively mild, wet winters resulting in snow conditions which restricted access to forage and caused several catastrophic die-offs. No live caribou were seen during six hours of aerial surveys over Inglefield Land, Thule District, Northwest Greenland, during July 1978. No fresh caribou sign was found during five days of searching in the Rensselaer Bay area of Inglefield Land. Unless some individuals were not detected or subsequent emigration from Ellesmere Island has occurred, the Inglefield Land caribou population has been extirpated. The Thule District caribou population apparently originated from barren-ground caribou (R. t. groenlandicus Gmlin) which emigrated from Southwest Greenland, rather than from Peary caribou (R. t. pearyi Allen) from Ellesmere Island.Key words: caribou, Rangifer, Greenland, Thule District, Inglefield Land, High ArcticMots clés: caribou, Rangifer, Groenland, district de Thule, terre d'Inglefield, nord de l'Arctiqu

Factors Influencing Nest Attendance and Time-activity Budgets of Peregrine Falcons in Interior Alaska

An essential prerequisite to examining the impacts of anthropogenic disturbance on avian nesting activities is understanding the intrinsic and extrinsic factors that influence the birds' allocation of time to breeding behaviors. We examined factors influencing nest attendance and time-activity budgets of peregrine falcons (Falco peregrinus anatum) breeding along the Tanana River in Alaska in 1995, 1996, and 1997. First, as is typical of most bird species with nidicolous young and biparental care, females attended the nest more than males and, as the nesting cycle progressed, female attendance decreased to levels similar to those of males. Second, nest area attendance followed a circadian rhythm; parents attended the nest area less during early morning and late evening, which are prime hunting periods, than during late morning. Finally, although females typically performed most of the incubating, the division of labor between males and females during incubation differed among pairs. Higher attendance in the nest area by females during incubation appeared to be associated with more young fledged among successful pairs.Une condition indispensable pour examiner les retombées de la perturbation anthropique sur la nidification aviaire est reproducteurs. On a étudié les facteurs qui ont influencé la présence au nid et les budgets temps-activités des faucons pèlerins (Falco peregrinus anatum) nichant le long de la rivière Tanana en Alaska en 1995, 1996 et 1997. Tout d'abord, comme on doit s'y attendre de la plupart des espèces aviaires dont les petits sont nidicoles et où les soins sont biparentaux, les femelles étaient présentes au nid plus que les mâles et, à mesure que le cycle de nidification avançait, la présence des femelles diminuait à des niveaux semblables à ceux de la présence des mâles. Deuxièmement, la présence aux environs du nid suivait un rythme circadien, les parents passant moins de temps près du nid au début de la matinée et en fin de soirée - temps forts de la chasse - qu'en fin de et femelles durant l'incubation différait selon les paires. Durant l'incubation, la présence plus affirmée des femelles dans la zone du nid semblait être associée à un nombre supérieur de petits qui prenaient leur envol chez les paires qui avaient réussi à se reproduire

Measurements, Chick Meals and Breeding Distribution of Dovekies (Alle alle) in Northwest Greenland

This paper reports the results of an investigation of Dovekies (Alle alle L.) breeding near Cape Atholl and Siorapaluk in the Thule District, Northwest Greenland during July and August 1978. Mean values for body measurements of breeding birds were: total length = 218.2 mm (n = 265), wing length = 122.9 mm (n - 266), tail length - 40.8 mm (n = 266) and body weight = 150.5 g (n = 209). Most measurements between the sexes were not significantly different, but mean body weight of males (153.8 g) was significantly greater than that of females (147.2 g). Body weight was highly correlated with wing length and total length in males, but not in females. Food delivered to nestlings consisted primarily of copepods (Calanus hyperboreas and C. glacialis) and amphipods (Parathemisto libellula and Apherusa glacialis). Size of chick meals delivered by male and female parents did not differ significantly and average meal weight was 3.48 g (sd = 1.24, n = 204) with mean weight of meals increasing through the chick-rearing period. General information is presented on measurements of subadults, timing of breeding, feeding areas, population size and colony attendance, and predation and disturbance. The distribution of Dovekie colonies in the Thule District is reviewed and compared with earlier information.Key words: Dovekie, morphometrics, chick diet, seabirds, NW GreenlandMots clés: Dovekie, morphométrie, régime des oisillons, oiseaux marins, nord-ouest du Groenlan

Defense responses of Hevea brasiliensis to elicitors from root rot fungi

L'élicitation de quelques réactions de défense du système racinaire de l'Hévéa (#Hevea brasiliensis) aux attaques du #Rigidoporus lignosus$ a été réalisée en injectant des extraits des parois fongiques dans les racines de jeunes plantes âgées de 1 mois. Une étude de la cinétique a révélé, au microscope optique, une induction de la lignification 3, 8, 15 et 45 jours après l'injection d'éliciteurs. Les résultats obtenus montrent que certaines réactions de défense des racines des plantes ligneuses peuvent être stimulées par des éliciteurs fongiques dans le but de renforcer les barrières structurales des tissus hôtes. (D'après résumé d'auteur

Use of Fatty Acid Analysis to Determine Dispersal of Caspian Terns in the Columbia River Basin, U.S.A.

Lethal control, which has been used to reduce local abundances of animals in conflict with humans or with endangered species, may not achieve management goals if animal movement is not considered. In populations with emigration and immigration, lethal control may induce compensatory immigration, if the source of attraction remains unchanged. Within the Columbia River Basin (Washington, U.S.A.), avian predators forage at dams because dams tend to reduce rates of emigration of juvenile salmonids (Oncorhynchus spp.), artificially concentrating these prey. We used differences in fatty acid profiles between Caspian Terns (Hydroprogne caspia) at coastal and inland breeding colonies and terns culled by a lethal control program at a mid-Columbia River dam to infer dispersal patterns. We modeled the rate of loss of fatty acid biomarkers, which are fatty acids that can be traced to a single prey species or groups of species, to infer whether and when terns foraging at dams had emigrated from the coast. Nonmetric multidimensional scaling showed that coastal terns had high levels of C20 and C22 monounsaturated fatty acids, whereas fatty acids of inland breeders were high in C18:3n3, C20:4n6, and C22:5n3. Models of the rate of loss of fatty acid showed that approximately 60% of the terns collected at Rock Island Dam were unlikely to have bred successfully at local (inland) sites, suggesting that terns foraging at dams come from an extensive area. Fatty acid biomarkers may provide accurate information about patterns of dispersal in animal populations and may be extremely valuable in cases where populations differ demonstrably in prey base

Susceptibility of Juvenile Steelhead to Avian Predation: the Influence of Individual Fish Characteristics and River Conditions

Identification of the factors that influence susceptibility to predation can aid in developing management strategies to recover fish populations of conservation concern. Predator-prey relationships can be influenced by numerous factors, including prey condition, prey size, and environmental conditions. We investigated these factors by using juvenile steelhead Oncorhynchus mykiss from the Snake River (Pacific Northwest, USA), a distinct population segment that is listed as threatened under the U. S. Endangered Species Act. During 2007-2009, steelhead smolts (n = 25,909) were captured, examined for external condition characteristics (e. g., body injuries, descaling, external signs of disease, fin damage, and ectoparasite infestations), marked with passive integrated transponder (PIT) tags, and released to continue their out-migration. Recoveries of PIT tags on a downstream colony of Caspian terns Hydroprogne caspia (n = 913 tags) indicated that steelhead susceptibility to Caspian tern predation increased significantly with decreases in steelhead external condition, decreased water discharge, and decreased water clarity. Susceptibility to Caspian tern predation also increased with increasing steelhead fork length up to 202 mm but then decreased for longer steelhead. Recoveries of PIT tags on a downstream colony of double-crested cormorants Phalacrocorax auritus (n = 493 tags) indicated that steelhead susceptibility to double-crested cormorant predation increased significantly with declining external condition of steelhead, and that steelhead of hatchery origin were more susceptible than their wild counterparts. Results indicate that steelhead susceptibility to avian predation is dependent on fish condition and length and is influenced by river conditions and rearing environment.Keywords: Snake River, Avoidance behavior, Relative vulnerability, Double crested cormorants, Foraging patterns, Chinook salmon, Passive integrated transponders, Caspian terns, Lower Columbia River, Salmon Oncorhynchus tshawytsch

Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks

Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the application of endocrine research in ecological and evolutionary studies of wild birds by providing a long-term measure of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls. Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments. This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress affects feather development

Developing Nondestructive Techniques for Managing Conflicts Between Fisheries and Double-Crested Cormorant Colonies

Double-crested cormorants (Phalacrocorax auritus) have been identified as the source of significant mortality to juvenile salmonids (Oncorhynchus spp.) in the Columbia River Basin. Management plans for reducing the size of a large colony on East Sand Island (OR, USA) in the Columbia River estuary are currently being developed. We evaluated habitat enhancement and social attraction as nondestructive techniques for managing cormorant nesting colonies during 2004–2007. We tested these techniques on unoccupied plots adjacent to the East Sand Island cormorant colony. Cormorants quickly colonized these plots and successfully raised young. Cormorants also were attracted to nest and raised young on similar plots at 2 islands approximately 25 km from East Sand Island; 1 island had a history of successful cormorant nesting whereas the other was a site where cormorants had previously nested unsuccessfully. On a third island with no history of cormorant nesting or nesting attempts, these techniques were unsuccessful at attracting cormorants to nest. Our results suggest that some important factors influencing attraction of nesting cormorants using these techniques include history of cormorant nesting, disturbance, and presence of breeding cormorants nearby. These techniques may be effective in redistributing nesting cormorants away from areas where fish stocks of conservation concern are susceptible to predation, especially if sites with a recent history of cormorant nesting are available within their foraging or dispersal range.Keywords: salmonids, social attraction, Phalacrocorax auritus, predation, habitat enhancement, cormoran

Quantifying Avian Predation on Fish Populations: Integrating Predator-Specific Deposition Probabilities in Tag Recovery Studies

Accurate assessment of specific mortality factors is vital to prioritize recovery actions for threatened and endangered species. For decades, tag recovery methods have been used to estimate fish mortality due to avian predation. Predation probabilities derived from fish tag recoveries on piscivorous waterbird colonies typically reflect minimum estimates of predation due to an unknown and unaccounted-for fraction of tags that are consumed but not deposited on-colony (i.e., deposition probability). We applied an integrated tag recovery modeling approach in a Bayesian context to estimate predation probabilities that accounted for predator-specific tag detection and deposition probabilities in a multiple-predator system. Studies of PIT tag deposition were conducted across three bird species nesting at seven different colonies in the Columbia River basin, USA. Tag deposition probabilities differed significantly among predator species (Caspian terns Hydroprogne caspia: deposition probability = 0.71, 95% credible interval [CRI] = 0.51–0.89; double-crested cormorants Phalacrocorax auritus: 0.51, 95% CRI = 0.34–0.70; California gulls Larus californicus: 0.15, 95% CRI = 0.11–0.21) but showed little variation across trials within a species or across years. Data from a 6-year study (2008–2013) of PIT-tagged juvenile Snake River steelhead Oncorhynchus mykiss (listed as threatened under the Endangered Species Act) indicated that colony-specific predation probabilities ranged from less than 0.01 to 0.17 and varied by predator species, colony location, and year. Integrating the predator-specific deposition probabilities increased the predation probabilities by a factor of approximately 1.4 for Caspian terns, 2.0 for double-crested cormorants, and 6.7 for California gulls compared with traditional minimum predation rate methods, which do not account for deposition probabilities. Results supported previous findings on the high predation impacts from strictly piscivorous waterbirds nesting in the Columbia River estuary (i.e., terns and cormorants), but our findings also revealed greater impacts of a generalist predator species (i.e., California gulls) than were previously documented. Approaches used in this study allow for direct comparisons among multiple fish mortality factors and considerably improve the reliability of tag recovery models for estimating predation probabilities in multiple-predator systems

North or south? Niche separation of endemic red-legged kittiwakes and sympatric black-legged kittiwakes during their non-breeding migrations

AIM: Species that breed sympatrically often occupy different foraging niches to mitigate competition for prey. When resource availability declines at the end of the breeding season, some animals migrate to regions with more favourable environmental conditions. When these life-history traits combine, foraging habitat preferences may continue to influence migration patterns and habitat utilization. The Bering Sea is home to the red-legged kittiwake (RLKI), Rissa brevirostris, which is endemic, and the black-legged kittiwake (BLKI), Rissa tridactyla, which has a circumpolar breeding distribution. Since the 1970s, numbers of RLKIs at the largest colony have declined and then recovered, whilst the BLKI population has remained stable. Knowledge of the migration ecology of kittiwakes is key to understanding differences in population trajectories, and predicting possible future responses of these species to climate change. LOCATION: Pribilof Islands, Bering Sea, subarctic North Pacific. METHODS: Using geolocation loggers, we tracked adult RLKIs and BLKIs during their non-breeding migrations. We used iterative methods to assess suitable sample sizes for determining space use. Kittiwakes are surface foragers; therefore we used wet-dry data to distinguish active foraging behaviour and to test the species’ responses to environmental conditions. Stable isotope ratios of feathers grown during the non-breeding period were used to assess dietary niche. RESULTS: RLKIs remained largely in the Bering Sea, where they experienced colder conditions and shorter days; individual birds used multiple habitats, including the continental shelves, the sea-ice edge and pelagic waters. In contrast, BLKIs migrated to the subarctic North Pacific, where they dispersed laterally across the basin; the majority of birds travelled to the western subarctic. RLKIs spent less time actively foraging than BLKIs, and consumed higher trophic-level prey. MAIN CONCLUSIONS: The disparate wintering ranges and foraging behaviour of BLKIs and RLKIs suggest distinct environmental factors drive variation in overwinter survival. A strong association with sea ice, and specialization both in diet and foraging behaviour, may make RLKIs particularly vulnerable to climatic change.Keywords: Sibling species, Geolocation, Non-breeding habitat, Rissa tridactyla, Bering Sea, North Pacific, Seabird, Resource partitioning, Ecological segregation, Rissa brevirostri