Search results for "seabird"
showing 9 items of 39 documents
Contrasting age-specific recruitment and survival at different spatial scales: A case study with the European storm petrel
2009
Evolutionary studies on optimal decisions or conservation guidelines are often derived by generalising patterns from a single population, while inter-population variability in life-history traits is seldom considered. We investigated here how survival and recruitment probabilities changed with age at different geographical scales using the encounter histories of 5523 European storm petrels from three Mediterranean colonies, and also how our estimates of these parameters might be expected to affect population growth rates using population matrix models. We recorded similar patterns among colonies, but also important biological differences. Local survival, recruitment and breeding success inc…
Modeling temporal and spatial colony‐site dynamics in a long‐lived seabird
2003
We studied the determinants of colony site dynamics in Audouin's gull, Larus audouinii, breeding in a small archipelago of the western Mediterranean. Data on island occupation were available for a series of 25 years, since first colonization of the archipelago in 1973. Group behavior was studied in relation to the components of dispersal: permanence or abandonment (extinction) on an island previously occupied and permanence or occupation (colonization) of another island. Generalized Linear Mixed Models (GLMMs) were used to identify the relative contribution of each explanatory variable to the probability of colony abandonment. Gulls showed a low probability (3%) of abandoning one of the isl…
Unconditional adoption rules out the need for parent–offspring recognition in a single‐brooded colonial seabird
2021
Parent–offspring recognition (POR) is fundamental in colonial birds when the potential intermingling of chicks is higher due to the large number and proximity of nests. In species with isolated nests, where chick presence in the nest is strong contextual evidence of kinship, there might be circumstances when the parent might doubt the identity of the chick, but not enough to reject it. Olfactory-based recognition of conspecifics and nest sites in birds has gained strong evidence suggesting a potential role of olfaction in POR. Despite that, there are no studies testing it. We used Scopoli's shearwater (Calonectris diomedea) as model colonial single-brooded species with a developed olfactory…
Competition for breeding sites and site-dependent population regulation in a highly colonial seabird, the common guillemot Uria aalge
2004
Summary 1. The hypothesis of site-dependent population regulation predicts that birds utilize available nesting sites in a pre-emptive (ideal despotic) manner, leading to density dependence in heterogeneous habitats as poorer sites are used at higher population densities. At small population sizes adaptive site choice protects populations against fluctuations (the buffer effect). 2. Common guillemots Uria aalge (Pontoppidan) breed at high density on sea-cliffs. The population breeding on the Isle of May, Scotland increased by 60% between 1981 and 2000. A good nest-site is a prerequisite for successful breeding and there is much competition for the best sites. Throughout this period, site us…
Bottom-up control on macrobenthic communities in a guanotrophic coastal system.
2013
Soft bottom macrobenthic assemblage and sediment characteristics were studied from autumn 2008 to summer 2009 in three coastal ponds (Marinello ponds, Sicily, Italy) at increasing distances from a gull (Larus michahellis Naumann, 1840) colony to investigate the effect of seabird-induced eutrophication (i.e. guanotrophication) on macrobenthic communities. We hypothesized that enhanced nutrient concentration and organic load caused by guano input significantly alter the sedimentary condition of ponds, affecting benthic fauna through a bottom-up control. Polychaetes were the dominant taxon in the system, followed by amphipods, gastropods and bivalves. Macrobenthic patterns showed high variabil…
The role of maternal effects in host-parasite interactions: examination of the development of the immune defense in a colonial seabird, the black-leg…
2004
One of the main aims of evolutionary biology is to understand the mechanisms responsible for the phenotypic variation on which natural selection can act. Maternal effects occur when a mother's phenotype or her environment influence her offspring's phenotype. Despite the importance of such effects for the ecology of host-parasite interactions, their role has been relatively neglected to date. In this thesis, we examined how mothers influence the immune defense of their young in an environment that varies in space and time. This work has primarily focused on a colonial seabird, the black-legged kittiwake (Rissa tridactyla). Using this model, we have first shown that specific maternal antibodi…
Seabird influence on ecological processes in coastal marine ecosystems: an overlooked role?
2013
Coastal marine ecosystems and especially transitional environments host a large variety of birds, functioning as nesting sites for resident species and corridors for migratory ones. Seabirds activity may trigger movement of nutrients and organic matter between coastal boundaries, affecting their availability and processing. Consequently seabirds are often labelled as biotic vectors. While attention has been focused on the study of biodiversity level and migratory patterns of avifauna, there is little information on the effects of seabirds on ecological features (i.e. trophic status, biodiversity level, food web patterns, transfer of contaminants) in coastal marine ecosystems. To address the…