Granadeiro JP, Nunes M, Silva MC, Furness RW
Instituto da Conservação da Natureza, Lisbon
Anim Behav. 1998 Nov;56(5):1169-1176. doi: 10.1006/anbe.1998.0827.
Procellariiformes are well known for their low rates of food provisioning to their slow-growing chicks. In some species, the patterns of food delivery to chicks have been deduced from changes in their weight, obtained from periodic weighings. However, the behaviour of individual parents cannot be resolved using this method. In this study, we used a periodic weighing protocol with Cory's shearwater chicks on Selvagem Grande island, in the northeast Atlantic. In addition, we used an automatic logging system to examine the attendance of individual parents. In 1997, the chicks were fed infrequently, and were in significantly poorer condition, than in other years and at other colonies. This suggests that the adults were experiencing some difficulties in finding an adequate food supply close to the colony. Under these conditions, individual parents adopted a dual provisioning strategy, making both short and long foraging trips, a previously undescribed behaviour in any northern hemisphere petrel species. Although meals delivered to chicks were larger after long trips than after short trips, the average amount of food provisioned per day spent at sea decreased with increasing trip length, and so chicks did not benefit from longer trips. This finding suggests that long trips can be used to restore the adult's body condition, presumably depleted during short trips as shown previously for some petrels and albatrosses. The adoption of this flexible foraging strategy, which differs from the uniform intervals observed in Cory's shearwaters experiencing situations of 'normal' food abundance, may represent a mechanism through which breeding birds compromise between the needs of their chicks and the maintenance of their own body condition. Copyright 1998 The Association for the Study of Animal Behaviour.
鹱形目鸟类以向生长缓慢的雏鸟提供食物的频率较低而闻名。在一些物种中，通过定期称重获得雏鸟体重的变化，从而推断出给雏鸟喂食的模式。然而，使用这种方法无法分辨单个亲鸟的行为。在本研究中，我们对东北大西洋塞尔瓦任大岛上的科里氏剪水鹱雏鸟采用了定期称重方案。此外，我们使用自动记录系统来检查单个亲鸟的出勤情况。1997年，雏鸟的喂食频率很低，且状况明显比其他年份和其他繁殖地的雏鸟差。这表明成年亲鸟在靠近繁殖地的地方寻找充足食物供应时遇到了一些困难。在这种情况下，单个亲鸟采用了双重觅食策略，进行短途和长途觅食之旅，这是北半球任何海燕物种中以前未描述过的行为。尽管长途觅食后喂给雏鸟的食物量比短途觅食后多，但随着觅食行程长度的增加，每天在海上觅食所提供的平均食物量减少，因此雏鸟并未从更长的行程中受益。这一发现表明，长途行程可用于恢复成年亲鸟的身体状况，推测其身体状况在短途行程中会像之前在一些海燕和信天翁中所显示的那样被消耗。这种灵活觅食策略的采用，不同于在食物供应“正常”丰富情况下观察到的科里氏剪水鹱的均匀间隔模式，可能代表了一种繁殖鸟类在雏鸟需求和自身身体状况维持之间进行权衡的机制。版权所有1998年动物行为研究协会。
