Habitat utilization and breeding success of Leach's storm-petrel, Oceanodroma leucorhoa

It is generally assumed that individual organisms behave optimally. In terms of habitat utilization, die optimal habitat for any species is that which provides the optimum conditions for survival and reproduction. -- This study compared how Leach's Storm-Petrels, Oceanodroma leucorhoa, utilized forest and open habitat on Great Island, Newfoundland. Specifically, nesting habitats were compared in terms of slope, aspect, and peat compaction. The adaptive significance of habitat utilization was assessed through comparisons of burrow density, the proportions of active and occupied burrows, hatching success, chick growth, breeding success and predation risk. -- Forest and open habitats differed; open habitat had steeper slope and more compact soil than forest, which had deeper peat. Burrow density and activity were greater in forest than open habitat, indicating that Leach's Storm-Petrels actively selected forest over open habitat Clearly, based on area, forest habitat supported a greater number of breeding pairs. Moreover, birds nesting in forest exhibited greater hatching and breeding success than birds nesting in open habitat, thus storm-petrels nesting in forest were disproportionately more productive than storm-petrels nesting in open habitat. -- Avian predation of Leach's Storm-Petrels did not differ between forest and open habitats, but varied seasonally in both. Predation was much reduced in both habitats following the inshore movement of spawning Capelin, Mallotus villosis. -- The terrestrial flora of the habitats utilized by Leach's Storm-Petrels change over time, being influenced by other seabirds (e.g. gulls and puffins on Great Island). Forest habitat is estimated to have decreased by 17 % on Great Island over the past 25 years. Open habitat has been expanding, which will negatively affect the overall productivity of the Leach's Storm-Petrel colony. Generalizations to other Leach's Stonn-Petrel colonies in the northwest Atlantic are also made

Indirect effects of the availability of capelin and fishery discards: Gull predation on breeding storm-petrels

The Northwest Atlantic has undergone large-scale perturbations which have had profound effects on pelagic food webs. Over the past century, the increasing availability of human refuse and fishery discards have promoted the growth of Larus gull populations. During the 1990s, cold surface-water events have delayed the inshore movements of spawning capelin Mallotus villosus and fisheries closures have eliminated massive tonnages of discards. These circumstances have interacted to intensify food stress on gulls. We investigated gull predation in a large colony of Leach's storm-petrels Oceanodroma leucorhoa as an indirect consequence of the availability of prey and fishery discards. Predation did not differ between storm-petrels nesting in forest and open habitats even though gull nests were more often in close proximity to storm-petrel burrows in open habitat. In 1996 and 1997, gull predation on storm-petrels varied seasonally, with a significant decrease following the inshore movement of spawning capelin, a primary food that gulls consume and feed to their chicks. Capelin availability occurred considerably later in 1997, when gull predation on storm-petrels was greater and prolonged. The intensity of gull predation on storm-petrels appears to depend on the availability of spawning capelin inshore

The reproductive behaviour and ecology of Sabine's gulls (Xema sabini) in the eastern Canadian Arctic

Life history theory focuses on how phenotypic traits interact to determine an organism's fitness, which is generally measured in terms of survival and reproduction. An animal's behaviour is a critical component in its ability to survive and reproduce, because natural selection promotes individuals that are behaviourally efficient. -- Like many avian species breeding at high latitudes, the reproductive behavior and ecology of Sabine's Gull (Xema sabini) has been rarely studied. This species nests in coastal wetland tundra across the Arctic, and winters at cold-water upwelling zones in the Tropics and Subtropics. It is considered an atypical gull, both morphologically and behaviourally, and is recognized as phylogenetically distinct. -- At East Bay, Southampton Island, Nunavut, Sabine's Gulls nested on mossy edges of freshwater ponds, and were non-randomly distributed across the study area and within nesting habitat. Compared with other gulls, they exhibit several distinct ecological traits. They had relatively short incubation and fledging periods, and, within 24 hours of hatching, families relocated to post-hatching territories at the shoreline. These aspects of their reproductive ecology, which differ from other gulls, are likely adaptive traits that have evolved in response to specific characteristics of their Arctic breeding areas. -- Sabine's Gulls also exhibit a number of behavioural traits that are typical of gulls. Pairs showed strong site-tenacity and mate-fidelity from year to year. Throughout incubation and early brooding, males and females showed high reproductive investment. Overall, they shared parental duties equally, although there was considerable variation among pairs. Sabine's Gulls distinguished between threatening and non-threatening species close to their nests, and both members of a pair were aggressive towards predators. Although the relative intensity of response did not change over time, it did differ among predator types. Reproductive success was variable among years, and indirectly influenced by availability of microtine rodents, via their shared predators. The local annual survival rate, estimated at 0.89 ± 0.04, was close to those of other gull and tern species. -- Overall, the evolution of Sabine's Gull life history traits appears to have been influenced by both their phylogeny and the particular ecological conditions of their breeding environment, and/or interactions between these

A Conceptual Model to Determine Vulnerability of Wildlife Populations to Offshore Wind Energy Development

As offshore wind energy development is planned in the United States, there is an increasing need for pre- and post-construction monitoring plans to be focused on species determined to be most vulnerable to hazards of a specific project. We propose a conceptual model that incorporates biological and sociological parameters. Specifically, we suggest that demographic, ethological/biological, and population sensitivity be considered with legal protection, economic importance, and/or stakeholder interest. We recommend that vulnerability determinations include qualitative and quantitative methods

Herring gull larus argentatus predation on Leach's Storm-petrels Oceanodroma Leucorhoa breeding on Great Island, Newfoundland

The east coast of Newfoundland, Canada, harbours some of the largest Leach's Storm-Petrel Oceanodroma leucorhoa colonies in the world. In 1997, we estimated the breeding population of Leach's Storm-Petrels on Great Island, Witless Bay, Newfoundland at 269 765 ± 27 769 (213 866 - 325 664) pairs. This is similar to a previous estimate from 1979 of 252 910. A shift in distribution has occurred with more petrels nesting in forested habitat and fewer in grass shrub meadows in 1997. Gull predation on seabirds has increased in Newfoundland in the 1990s as a response to a variety ofchanges in the marine ecosystem. We estimated that gulls killed 49189 Leach's Storm-Petrels in 1997. However, in the face of this large kill, the breeding populations does not appear to have substantially declined. Recruitment from other large colonies may be maintaining the breeding population on Great Island

Offshore Observations of Eastern Red Bats (<i>Lasiurus borealis</i>) in the Mid-Atlantic United States Using Multiple Survey Methods

<div><p>Little is known about the migration and movements of migratory tree-roosting bat species in North America, though anecdotal observations of migrating bats over the Atlantic Ocean have been reported since at least the 1890s. Aerial surveys and boat-based surveys of wildlife off the Atlantic Seaboard detected a possible diurnal migration event of eastern red bats (<i>Lasiurus borealis</i>) in September 2012. One bat was sighted approximately 44 km east of Rehoboth Beach, Delaware during a boat-based survey. Eleven additional bats were observed between 16.9 and 41.8 km east of New Jersey, Delaware, and Virginia in high definition video footage collected during digital aerial surveys. Observations were collected incidentally as part of a large baseline study of seabird, marine mammal, and sea turtle distributions and movements in the offshore environment. Digital survey methods also allowed for altitude estimation for several of these bats at >100 m above sea level. These observations provide new evidence of bat movements offshore, and offer insight into their flight heights above sea level and the times of day at which such migrations may occur.</p> </div