How do seabirds modify their search behaviour when encountering fishing boats?

Seabirds are well known to be attracted by fishing boats to forage on offal and baits. We used recently developed loggers that record accurate GPS position and detect the presence of boats through their radar emissions to examine how albatrosses use Area Restricted Search (ARS) and if so, have specific ARS behaviours, when attending boats.
As much as 78.5% of locations with a radar detection (contact with boat) during a trip occurred within ARS: 36.8% of all large-scale ARS (n=212) and 14.7% of all small-scale ARS (n=1476) were associated with the presence of a boat. During small-scale ARS, birds spent more time and had greater sinuosity during boat-associated ARS compared with other ARS that we considered natural.
For, small-scale ARS associated with boats, those performed over shelves were longer in duration, had greater sinuosity, and birds spent more time sitting on water compared with oceanic ARS associated with boats. We also found that the proportion of small-scale ARS tend to be more frequently nested in larger-scale ARS was higher for birds associated with boats and that ARS behaviour differed between oceanic (tuna fisheries) and shelf-edge (mainly Patagonian toothfish fisheries) habitats.
We suggest that, in seabird species attracted by boats, a significant amount of ARS behaviours are associated with boats, and that it is important to be able to separate ARS behaviours associated to boats from natural searching behaviours. Our study suggest that studying ARS characteristics should help attribute specific behaviours associated to the presence of boats and understand associated risks between fisheries.

众所周知，海鸟会被渔船吸引，以渔船丢弃的内脏及饵料为食。本研究采用新近研发的定位记录仪——其可精准记录GPS位置，并通过雷达信号侦测船只动向——来探究信天翁在伴随船只活动时的区域限制搜索（Area Restricted Search, ARS）模式，以及是否存在针对伴船行为的特异性ARS行为。
在航行期间，雷达侦测到船只（即与船只接触）的位置中，有高达78.5%处于ARS范围内：所有大型ARS（n=212）中有36.8%、所有小型ARS（n=1476）中有14.7%与船只活动存在关联。在小型ARS阶段，相较于我们认定的自然型ARS，伴船ARS状态下的海鸟停留时长更长，路径弯曲度也更高。
对于与船只相关的小型ARS而言，在大陆架区域开展的此类ARS相较于远洋伴船ARS，其持续时长更长、路径弯曲度更高，且海鸟停留在水面的时间也更长。我们还发现，伴随船只活动的海鸟，其小型ARS嵌套于大型ARS中的比例更高；且不同栖息环境下的ARS行为存在显著差异：远洋环境（对应金枪鱼渔业）与陆架边缘区域（主要为巴塔哥尼亚牙鱼渔业）的ARS行为各不相同。
我们认为，在受船只吸引的海鸟物种中，有相当比例的ARS行为与船只活动相关，因此将伴船ARS行为与自然搜索行为区分开来具有重要意义。本研究表明，对ARS特征展开分析，有助于甄别与船只活动相关的特异性行为，并助力理解渔业活动带来的相关风险。