Publicação
Consequences of migratory choices and mercury accumulation in cory's shearwaters
| Resumo: | The migratory decisions of Cory’s shearwaters (Calonectris borealis) potentially have an impact on individuals, producing carry-over effects, with implications for population structure and dynamics. The main goals in this study were to compare the distribution of a studied population of Cory’s Shearwaters, at Selvagem Grande, during the non-breeding period; investigate the influence of wintering ground on the date of arrival at the colony and body condition on arrival and how these factors could relate with reproductive success and see how these previously mentioned factors were influenced by mercury (Hg) accumulation in the wintering ground and how this contaminant was distributed amongst wintering locations. Most of the studied individuals migrated to oceanic regions around southern Africa. Individuals wintering in the Canary Current were all males and the first to return to breeding grounds. Relative to reproduction, overall laying and hatching success were high and close to values recorded for other seabirds. Females handled in March had a higher percentage of egg presence in the respective nest when compared to males. Laying success did not increase with early arrival dates. Males having wintered in the Canary Current had a laying success of 57.9% and those wintering in southern Africa 75.4%. Body condition did not have any relationship with reproduction and arrival date, but it seemed slightly lower for male individuals wintering in Canary Current, in comparison with the other males. The mean mercury concentration deposited in winter grown flight feathers of adult Cory’s Shearwaters was 5.80 ± 2.3 mg/kg, with no difference between males and females. Males wintering in the Canary current registered the lowest mercury burden when compared with birds spending the winter in southern Africa locations. Mercury concentrations due to the exposure in wintering grounds did not seem to affect the duration of migration, laying success neither body condition amongst individuals. However, there was a positive correlation between arrival dates from southern Africa males and mercury concentrations, in which individuals arriving later had higher mercury concentrations. It was possible to assess a certain influence and carry-over effects from wintering locations in these individuals’ traits. The collected data provides information about this species distribution and influences of its distribution in its life choices, which can be used to conservation measures. Also, using this species as a biomonitor for environmental mercury provides important insights about its levels in wintering areas. |
|---|---|
| Autores principais: | Reis, Bianca Raquel Correia dos |
| Assunto: | Aves marinhas - Habitat Cagarras--Habitat Mercúrio - Toxicidade |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | The migratory decisions of Cory’s shearwaters (Calonectris borealis) potentially have an impact on individuals, producing carry-over effects, with implications for population structure and dynamics. The main goals in this study were to compare the distribution of a studied population of Cory’s Shearwaters, at Selvagem Grande, during the non-breeding period; investigate the influence of wintering ground on the date of arrival at the colony and body condition on arrival and how these factors could relate with reproductive success and see how these previously mentioned factors were influenced by mercury (Hg) accumulation in the wintering ground and how this contaminant was distributed amongst wintering locations. Most of the studied individuals migrated to oceanic regions around southern Africa. Individuals wintering in the Canary Current were all males and the first to return to breeding grounds. Relative to reproduction, overall laying and hatching success were high and close to values recorded for other seabirds. Females handled in March had a higher percentage of egg presence in the respective nest when compared to males. Laying success did not increase with early arrival dates. Males having wintered in the Canary Current had a laying success of 57.9% and those wintering in southern Africa 75.4%. Body condition did not have any relationship with reproduction and arrival date, but it seemed slightly lower for male individuals wintering in Canary Current, in comparison with the other males. The mean mercury concentration deposited in winter grown flight feathers of adult Cory’s Shearwaters was 5.80 ± 2.3 mg/kg, with no difference between males and females. Males wintering in the Canary current registered the lowest mercury burden when compared with birds spending the winter in southern Africa locations. Mercury concentrations due to the exposure in wintering grounds did not seem to affect the duration of migration, laying success neither body condition amongst individuals. However, there was a positive correlation between arrival dates from southern Africa males and mercury concentrations, in which individuals arriving later had higher mercury concentrations. It was possible to assess a certain influence and carry-over effects from wintering locations in these individuals’ traits. The collected data provides information about this species distribution and influences of its distribution in its life choices, which can be used to conservation measures. Also, using this species as a biomonitor for environmental mercury provides important insights about its levels in wintering areas. |
|---|