1,720,976 research outputs found
The effects of herring gulls (Larus argentatus) on the vegetation and soils of their nesting sites /
No full textThis study was initiated to determine the effects of Herring Gulls (Larus argentatus) on the vegetation and soils of their nesting sites within the Mingan Island National Park Reserve. Both vegetation (species composition, cover, density, growth) and soil characteristics (pH, N, P, K, Ca, Mg) were monitored throughout the 1995 breeding season. Exclosures were installed within the colonies as control sites to prevent gull activity and these were compared to "treatment plots" or areas where gulls were present. All plants located at the study sites were native perennials with the exception of Stellaria, a native annual. Ledum groenlandicum was the only plant species significantly affected by gull activities. Both % cover and shoot growth for Ledum were greater in the exclosures than in the treatment plots over the breeding season. The gulls were also found to significantly increase pH and phosphorous levels in the soil through the deposition of faeces. Gull roosting sites were found to have higher nutrient levels than the nesting areas (treatment plots). The gulls appear to have minor effects over the short term, however the increases in soil nutrients may lead to significant changes over the long term. It is therefore imperative the exclosures remain in place to monitor for any long term changes which may occur
Determining rates of intraspecific nest parasitism in a colony of Red-breasted Mergansers (Mergus serrator) using microsatellite analysis
No full textThe rate of intraspecific nest parasitism was determined for a colony of Red-breasted Mergansers (Mergus serrator) nesting on the Tern Islands in Kouchibouguac National Park, New Brunswick. In order to recognize instances of nest parasitism, field criteria and microsatellite analysis testing for parentage between attending hens and the eggs in their nests were used. Traditionally, molecular analysis has involved collecting blood samples from females and offspring, however, for the purpose of this study, DNA was extracted successfully from feathers, egg membranes, and unhatched embryos which were collected during the summers of 1999 and 2000. A total of 8 primer pairs which amplified microsatellite loci in closely related avian species were tested (Sfimu-2, Sfimu-3, Sfimu-4, Sfimu-5, Sfimu-6, Sfimu-7, Bcamu-6, and Alamu-1). Four of these primers produced product of the expected size (Sfimu-3, Sfimu-4, Sfimu-7, and Bcamu-6). Amplification of these loci, however was inconsistent and subsequent sequence analysis revealed that the amplicons did not contain tandem repeats and therefore were not useful in genotyping. From field criteria we were able to establish rates of parasitism of 46% and 44% for each season. Rates of parasitism tended to be higher at the beginning of the season, compared to nests initiated later. Field criteria bring support to several hypotheses on causes of nest parasitism, indicating that more than one may influence rates of parasitism in a population
Diet and reproductive success of herring gulls nesting on the middle north shore of the Gulf of St. Lawrence
No full textBreeding biology and diet of Herring Gulls Larus argentatus were studied on Ile Nue, in the Mingan Archipelago National Park Reserve, in the Gulf of St. Lawrence. Nesting parameters were measured 1994--1996, and fledging success and diet were followed in 1996. Clutch size was low in all three years of the study, and hatching success was low in 1995. Low clutch size and hatching success could not be explained by researcher disturbance, predation, or competition for nest sites, leaving food-stress as the most likely explanation. To reduce the biases associated with determining diet, we used four methods to estimate diet. The 1996 breeding season was divided into three periods using changes in the number of gulf pellets collected from roost sites as an indirect measure of dietary changes; these periods corresponded to the pre-spawning, spawning, and post-spawning periods of capelin Mallotus villosus. (Abstract shortened by UMI.
Aggression among captive mallards and black ducks during the breeding season
No full textThe behaviour of captive mallards (Anas platyrhynchos) and black ducks (Anas rubripes) was studied from the end of March to mid-June in 1991 and 1992 to determine the extent of interspecific aggression exhibited and the effect of sympatry and allopatry on interactions between the two species.Mallards were more aggressive than black ducks regardless of sex and origin, though both species were equally attacked in both years, male ducks were more aggressive and more attacked than female ducks regardless of species and origin in both years, and ducks of sympatric origin were more aggressive than ducks of allopatric origin in 1991 regardless of sex and species while the opposite was true in 1992.Site attachment was observed in 7 of 9 experiments performed in 1992. In the experiments involving site attachment, almost all of the activity centered around the feeding stations, not around the nesting platforms
Ecology of the wood turtle, Clemmys insculpta, Québec, Canada
No full textThe most northeasterly population of wood turtles (Clemmys insculpta ) was studied during 1996 and 1997 in Quebec, Canada. A total of 188 turtles (55 males, 83 females, and 50 immatures) was captured, measured and marked for future identification. The adult sex ratio was not significantly different from 1:1. Males were significantly larger than females for measures of carapace length, 214.5 and 201 mm, respectively. Wood turtles from northern populations are larger than those from southern regions. The population density was estimated to be 0.44 turtles/hectare. Courtship occurred in the spring but was more common in the fall. Nesting occurred in mid-June with nesting activity taking place at all times of the day but more frequently in early morning and evening. Females migrated over 3 km to a nesting area and exhibited nest fidelity. Sixty-six percent of turtles nested in 2 consecutive yr and these females were significantly larger than turtles that nested in only 1 yr of the study. There was no mammalian predation but, some arthropods were suspected of being predators. Mean clutch size was 10.1 (range = 5--20) eggs. Comparisons with other populations of C. insculpta are also made
Aspects of the Nesting Ecology of the Eastern Bluebird (Sialia sialis) in Southwestern Quebec
No full textNote:Aspects of the nesting ecology of the Eastern Bluebird (Qialig sigli§) were studied during 1984 and 1985. An analysis of egg measurements revealed that clutch correlated with egg length (p < 0.001), size is significantly width (p < 0.01) and weight (p < 0.001). Egg size decreased as clutch size decreased.Hatching success and egg width were significantly correlated in 1984, with wider eggs being more likely to hatch. This relationship did not exist in 1985. Eggs in 1984 were significantly (p < 0.001) wider than eggs in 1985, but egg lengths were the same in both years. Egg sizes for the study area were similar to those recorded in the literature. […]L’écologie de la nidification de Merle Bleu (Sialia sialis) a été étudié au cours des étés 1984 et 1985. Des analyses de variance ont montré une association significative entre la taille de la couvée et la longueur de l'oeuf (p < 0.001), la largeur de l'oeuf (p < 0.01) et le poids de l'oeuf (p < 0.001). La taille des oeufs a diminué avec une diminution de la taille de la couvée. En 1984, une relation significative a toutefois été établie entre la largeur de l'oeuf et le succès d'éclosion. Les oeufs les plus larges ont eu un plus haut succès d'éclosion. Cette relation n'a pas été trouvée en 1985. Les œufs étaient significativement (p < 0.001) plus larges en 1984 qu'en 1985, mais il n'y avait aucune différence entre les longueurs. Les dimensions des oeufs recueillis au site étudié sont semblables aux valeurs présentées dans la littérature. […
Rearing and environmental factors influencing aberrant, affiliative, agonistic and nest-building behaviors in the Alala (Corvus hawaiiensis)
No full textThe future of the critically endangered `Alala (Corvus hawaiiensis ), with only seven individuals remaining in the wild, is wholly dependent upon the reproductive success of its captive population. Throughout the 1999 breeding season, behavioral observations were carried out on eight pairs of captive-reared Hawaiian crows. Due to the limited size of the captive population, and to avoid inbreeding, birds were paired based on their genetic profiles. As a result, there were differences in age and breeding experience within pairs. There were also differences in rearing conditions between mates. It has been suggested that social play and other affiliative behaviors may be important in young birds to form normal social bonds later in life. Affiliative behavior, such as allopreening and feeding other, was common among social-reared crows, but was virtually absent in isolate-reared individuals. Conversely, isolate-reared crows displayed various forms of aberrant behavior, including inappropriate play and self-mutilation, significantly more than the social-reared individuals. Since such behaviors occurred in the nest area throughout all phases of the breeding season, namely nest-building, egg-laying and incubation, it would appear as if early rearing condition plays a role in future reproductive success
The impact of human disturbance on the nesting success of the common eider Somateria mollissima /
No full textThe influence of human disturbance on the nesting success of the Common eider (Sonateria mollissima) was investigated in the Mingan Archipelago National Park Reserve during summers of 1994 to 19%. Six colonies were used, four located on open islets and two on forested islands. Three experimental treatments were used that entailed varying the frequency and time occurrence of visits in incubation. Every years, each treatment was applied to several eider colonies differing in the density of nesting gulls on the same island. During visits, incubating females were flushed and nest fate recorded. Several variables also were measured during visits describing female quality (assessed by clutch size and laying date) and nest site quality (assessed by nest concealment, distance to shore, vegetation height, and density of nesting gulls on the island). Results showed that frequency of visits did not affect nesting success of eiders, mainly because most observed nest failures occurred after the first visit The time occurrence of the first visit during incubation was of primary importance; eider nests visited early were much more affected by our presence. The nesting success of eiders was related to the density of associated colonies of nesting gulls only when visits occurred during early incubation. Female eiders of greater reproductive quality were those most successful when disturbed regularly. These females were in greater proportion on islands associated with lower density of nesting gulls, i.e., on forested islands rather than on open islets. Within colonies, they were mainly found nesting near shore where nest concealment is sparse. Results showed that visits to eider colonies can greatly affect their reproductive output. Visits during early incubation on open islets had the greatest impact
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
