Browsing by Author "Gatt, Marie Claire"
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- Data packageData from: Dynamic body acceleration increases by 20% during flight ontogeny of greylag geese (Anser anser)(2019-11-15) Gatt, Marie Claire; Quetting, Michael; Cheng, Yachang; Wikelski, MartinDespite our knowledge of the biophysical and behavioural changes during flight ontogeny in juvenile birds, little is known about the changes in the mechanical aspects of energy expenditure during early flight development, particularly in migratory species. Here, we investigate in a unique experimental setup how energy expended during flights changes over time beginning with early ontogeny. We calculate overall dynamic body acceleration (ODBA) as a proxy for energy expenditure in a group of hand raised Greylag Geese (Anser anser) trained to fly behind a microlight aircraft. We propose two potential hypotheses; energy expenditure either increases with increasing physiological suitability (the ‘physical development hypothesis’), or decreases as a result of behavioural improvements mitigating flight costs (the ‘behavioural development hypothesis’). There was a significant temporal increase of flight duration and ODBA over time, supporting the ‘physical development hypothesis’. This suggests that early on in flight ontogeny behavioural development leading to flight efficiency plays a weaker role in shaping ODBA changes than the increased physical ability to expend energy in flight. We discuss these findings and the implications of flight development on the life history of migratory species.
- Data packageData from: Pre-laying movements of Yelkouan Shearwaters (Puffinus yelkouan) in the Central Mediterranean [2012-2014](2019-04-12) Metzger, Benjamin; Lago, Paulo; Gatt, Marie ClaireThe pre-laying exodus (PLE) is considered a crucial period in the breeding biology of Procellariiformes as it determines the success of egg production within a season and, therefore, a population’s reproductive output. However, it has scarcely been studied compared to other stages of the annual cycle. Here we present the first pre-laying tracks of the vulnerable Yelkouan Shearwater (Puffinus yelkouan) through the Global Positioning System tracking of birds breeding on the Maltese islands in the Central Mediterranean, and compare PLE core utilisation areas to known areas used during the chick-rearing period. Females spend, on average, 13 days foraging during egg development, reaching an average maximum distance of 325.5 km from their breeding colony to forage at offshore areas mainly south of the Maltese islands; these journeys are of longer duration and cover a greater distance than those undertaken by males, and by females that are not developing an egg, during the same period. There is little to no overlap between the PLE core utilisation areas and those used during chick-rearing by the same populations. This confirms our expectations that the PLE differs from foraging trips undertaken outside of the egg development period. Our results highlight the need for more research into the factors attracting egg-producing females to the PLE foraging areas and the importance of trans-boundary marine protection for the conservation of vulnerable seabirds.
- Data packageData from: Pre-laying movements of Yelkouan Shearwaters (Puffinus yelkouan) in the Central Mediterranean [2016-2017](2019-04-12) Lago, Paulo; Austad, Martin; Metzger, Benjamin; Gatt, Marie ClaireThe pre-laying exodus (PLE) is considered a crucial period in the breeding biology of Procellariiformes as it determines the success of egg production within a season and, therefore, a population’s reproductive output. However, it has scarcely been studied compared to other stages of the annual cycle. Here we present the first pre-laying tracks of the vulnerable Yelkouan Shearwater (Puffinus yelkouan) through the Global Positioning System tracking of birds breeding on the Maltese islands in the Central Mediterranean, and compare PLE core utilisation areas to known areas used during the chick-rearing period. Females spend, on average, 13 days foraging during egg development, reaching an average maximum distance of 325.5 km from their breeding colony to forage at offshore areas mainly south of the Maltese islands; these journeys are of longer duration and cover a greater distance than those undertaken by males, and by females that are not developing an egg, during the same period. There is little to no overlap between the PLE core utilisation areas and those used during chick-rearing by the same populations. This confirms our expectations that the PLE differs from foraging trips undertaken outside of the egg development period. Our results highlight the need for more research into the factors attracting egg-producing females to the PLE foraging areas and the importance of trans-boundary marine protection for the conservation of vulnerable seabirds.