Socio-écologie du Skua antarctique a Pointe Géologie
International audience The breeding colony of Antarctic skuas Stercorarius mac- cormicki of Pointe Géologie, Adélie Land, has been studied since 1965. The number of birds present at the colony site increased from 80-90 in 1965/66 to 320 in 1976/77, and the number of breeding pairs from 29 to 40 duri...
| Main Authors: | , |
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| Format: | Article in Journal/Newspaper |
| Language: | French |
| Published: |
HAL CCSD
1979
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| Subjects: | |
| Online Access: | https://hal.archives-ouvertes.fr/hal-03530464/file/bitstream_118216.pdf https://hal.archives-ouvertes.fr/hal-03530464 |
| Summary: | International audience The breeding colony of Antarctic skuas Stercorarius mac- cormicki of Pointe Géologie, Adélie Land, has been studied since 1965. The number of birds present at the colony site increased from 80-90 in 1965/66 to 320 in 1976/77, and the number of breeding pairs from 29 to 40 during this period. In the same time interval, the average distance between nests was reduced from 110 to 65 m. The stability of the pair-bond is shown to be advantageous in Antarctic skuas. Breeding is higher in long-established pairs (Table I). The yearly production of eggs by the breeding birds increased from 44 in 1965/66 to 63 in 1976/77. However, the mortality rate of eggs increased in the same time period from 31 % to 48.6 %. The number of fledglings consequently remained more or less constant, ranging from 26 to 33 depending upon the year. This spectacular increase in the number of breeding pairs and in their fecundity apparently results from an artificial increase in the carrying capacity of the habitat. The establishment of a garbage dump close to the buildings of the French Antarctic base led to a progressive change in the food habits of the Antarctic skuas. Whereas these “ opportunistic ” birds originally preyed upon Adélie penguins’ eggs, chicks and carcases, they quickly began to feed exclusively upon human garbage. The use of this new permanent food source led to a rapid increase in the local population between 1970 and 1972. This population is now levelling off, having apparently reached a new equilibrium with the available resources. During the stage of exponential increase, most pairs successfully raised two chicks instead of one this is no longer the case now. The adaptation to a new food source has also changed the timing of the breeding season of the Antarctic skua. Instead of being closely synchronised with the breeding season of the sympa- tric Adélie penguins, the laying of Antarctic skua eggs now tends to be spread upon a much longer time period. Whereas the longest time interval between the ... |
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