|CALONECTRIS - Atlantic ocean-wide changes in sea surface temperature and trends on Cory’s shearwater foraging success, migration and population dynamics|
Paulo Catry (ISPA Instituto Universitário)
CESAM Responsible researcher - José Pedro Granadeiro
Programme - PTDC/MAR/71927/2006
Execution dates - 2008-10-01 - 2012-03-31 (42 Months)
Funding Entity - FCT
Funding for CESAM - 38.796 €
Total Funding - 134.787 €
Proponent Institution - ISPA Instituto Universitário
Universidade de AveiroUniversidade de LisboaParque Natural da Madeira
There is growing evidence that climate warming is occurring and models predict this trend will continue for several decades, at least. Recent changes are already affecting the distribution and phenology of many species, but we need a much better understanding, to be able to produce predictive models, capable of informing the public and decision-makers.
This project will study the relationships between climate fluctuations (particularly variation in sea surface temperature (SST)) and the behaviour, physiology and demography of a pelagic top marine predator, the Cory's shearwater (CS) Calonectris diomedea. CS are long distance migrants, nesting in temperate and sub-tropical NE Atlantic and wintering on the South Atlantic, mainly off the coasts of Brazil, Uruguay and southern Africa, with some reaching the Indian Ocean. They are ideal for a study linking climate and seabird demography and behaviour because (1) they are the object of a long-term population study, (2) they breed and winter in subtropical waters, where little research of this type has been carried out, (3) they are abundant and widespread, making them ideal organisms for environmental monitoring, (4) they are large enough to carry bird-borne data loggers, and (5) their biology is relatively well-known.
Many birds living in seasonal environments, including the vast majority of seabirds, are migratory. Migration is a fascinating, but in many aspects a still poorly understood phenomenon. In recent years, many researchers have tracked the migrations of individual birds through the use of satellite telemetry. Revealing as those studies are, they have generally been unable to go beyond the description of broad patterns. The prohibitive costs of satellite tags have not allowed studies with large sample sizes.
This project will use two recently developed tools that are revolutionising research on bird migration:
First, bird-borne Geolocators (GLS) have recently proved highly valuable in describing long-distance movements of individuals. Their relatively moderate price will allow us to use a large number of units and go beyond simple descriptions of general patterns, focusing instead on interesting detail and hypothesis-testing. We will use GLS loggers that not only tell us the location of the birds, but also record activity (number and timings of take-offs and landings on the sea) and accurately record SST.
Furthermore, after calibration of the methodology with Geolocators, we will use the isotopic composition of feathers moulted in the winter quarters to further enlarge our samples and determine the wintering areas of large numbers of individuals.
This approach will allow us to test hypotheses seldom tackled in seabird migration studies such as: (1) do Cory's shearwaters adjust the timing and course of migratory movements to annual differences in climatic patterns and changes in SST, or are they faithful to their schedules and staging and wintering sites? (2) Do migratory patterns differ between adults of different ages and sexes (we will use a population of ringed, known-age birds), (3) Are the details of the migratory schedule and routes affected by the previous season's breeding success? (4) Do activity levels (expressing foraging effort) vary with wintering grounds? And do they correlate with spatial and temporal variation in SST?
We will also look at the quality of the feathers moulted in different wintering areas by different individuals, and contrast those to SST, activity levels, broad diet trends (assessed using stable isotopes) and characteristics of the individual birds. Again, this is a pioneering study, never, to our knowledge, attempted before. Feather quality might provide a link between events in the wintering and breeding quarters. Such types of links (but mediated by different mechanisms) have recently been described for small terrestrial birds and are highly relevant to the fields of life-history strategy and conservation biology.
Furthermore, to better understand the fine-scale mechanisms linking climate, SST and several aspects of the demography and behaviour of seabirds, we will investigate the effects of short-term (weekly and daily) variation in SST on the diet and feeding success of Cory's shearwaters at Selvagem Grande (Madeira - Portugal). Birds will be equipped with temperature loggers attached to their legs. Daily variation of mass of adults and chicks will be monitored to estimate foraging success. Dietary samples will be collected.
Finally, we will use demographic data, collected over 25 years at Selvagem Grande, to relate broad climatic patterns (revealed, for example, by the North Atlantic Oscillation Index (NAO) and the Southern Oscillation Index (SOI)) to predator demographic responses.
Data gathered in the field study will allow the modelling of future trends and will represent an important baseline against which future monitoring may be compared.