Biology Department, Life Science Centre Dalhousie University, Halifax, Nova Scotia, Canada.
Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada.
PLoS One. 2023 Sep 27;18(9):e0290707. doi: 10.1371/journal.pone.0290707. eCollection 2023.
Most vertebrate offspring must transition from the relative security of parental care (nutrition and protection) to independent foraging. Offspring face many challenges during this critical period, particularly in species where parental care ends at weaning, such as the grey seal (Halichoerus grypus). We studied the development of movement behaviour in naïve grey seal pups from their first trips to sea to about five months of age. Twenty-five (12 males and 13 females) newly-weaned pups were fitted with satellite-linked GPS tags on Sable Island, Nova Scotia, Canada in January 2016. The influence of fixed effects (pup size, sex, week) and the random effect of pup identity on trip characteristics were examined. Movement behaviour was analyzed using a move persistence mixed-effects model. Habitat use was highly variable among individuals and covered much of the geographic distribution of the population. Unlike older juveniles, subadults, and adults in this population, most naïve pups used multiple haulout sites to begin and end trips. There was little evidence of area-restricted search behaviour during trips, suggesting that naïve pups were using an opportunistic foraging tactic that may result in more variable foraging success than that of older, experienced animals. Naïve pups made longer trips with longer haulout durations between them than observed for older greys seals. Males and females differed in some trip characteristics, but sex effects were small over the first few months of life. Offspring size at weaning was not a useful predictor of trip characteristics. Move persistence of grey seal pups was initially high and then decreased over time as individuals gained experience. Both intrinsic and extrinsic factors were influential on the movements of grey seal pups. Greater body length at weaning, longer duration spent on shore after weaning, shallower water column depth, and farther distance from shore were all associated with lower move persistence. Female grey seal pups had lower move persistence than males. Overall, the movements of naïve grey seal pups during the first few months of life were characterized by extensive exploration, but move persistence decreased over time suggesting they may be using an exploration-refinement foraging tactic.
大多数脊椎动物后代必须从父母照顾（营养和保护）的相对安全过渡到独立觅食。在这个关键时期，后代面临许多挑战，特别是在父母照顾在断奶时结束的物种中，例如灰海豹（Halichoerus grypus）。我们研究了从第一次下海到大约五个月大的新生灰海豹幼崽的运动行为发展。2016 年 1 月，在加拿大新斯科舍省的萨布尔岛，我们为 25 只（12 只雄性和 13 只雌性）刚断奶的幼崽配备了卫星连接的 GPS 标签。检查了固定效应（幼崽大小、性别、周）和幼崽身份的随机效应对旅行特征的影响。使用移动持久性混合效应模型分析了运动行为。个体之间的栖息地使用高度可变，覆盖了该种群地理分布的大部分。与该种群中的老年青少年、亚成年和成年动物不同，大多数新生幼崽使用多个上岸点开始和结束旅行。在旅行过程中几乎没有证据表明区域限制搜索行为，这表明新生幼崽正在使用一种机会主义觅食策略，这可能导致比老年、经验丰富的动物更可变的觅食成功率。新生幼崽的旅行时间更长，它们之间的上岸时间也更长。与观察到的较老的灰海豹相比，雄性和雌性在某些旅行特征上有所不同，但在生命的头几个月，性别影响很小。断奶时的幼崽大小不是旅行特征的有用预测指标。灰海豹幼崽的移动持久性最初很高，随着个体获得经验，随着时间的推移逐渐降低。内在和外在因素都对灰海豹幼崽的运动有影响。断奶时的体长较大、断奶后在岸上停留的时间较长、水层较浅以及离海岸的距离较远，与较低的移动持久性有关。雌性灰海豹幼崽的移动持久性低于雄性。总体而言，新生灰海豹幼崽在生命的头几个月的运动特征是广泛探索，但随着时间的推移移动持久性降低，这表明它们可能正在使用探索-精炼觅食策略。
