Effects of back‐mounted biologgers on condition, diving and flight performance in a breeding seabird

Biologging devices are providing detailed insights into the behaviour and movement of animals in their natural environments. It is usually assumed that this method of gathering data does not impact on the behaviour observed. However, potential negative effects on birds have rarely been investigated before field‐based studies are initiated. Seabirds which both fly and use pursuit diving may be particularly sensitive to increases in drag and load resulting from carrying biologging devices. We studied chick‐rearing adult common guillemots (Uria aalge) equipped with and without back‐mounted GPS tags over short deployments of a few days. Concurrently guillemots carried small leg‐mounted TDR devices (time‐depth recorders) providing activity data throughout. Changes in body mass and breeding success were followed for device equipped and control guillemots. At the colony level guillemots lost body mass throughout the chick‐rearing period. When‐equipped with the additional GPS tag, the guillemots lost mass at close to twice the rate they did when equipped with only the smaller leg‐mounted TDR device. The elevated mass loss suggests an impact on energy expenditure or foraging performance. When equipped with GPS tags diving performance, time‐activity budgets, and daily patterns of activity were unchanged, yet dive depth distributions differed. We review studies of tag‐effects in guillemots (Uria spp.) finding elevated mass loss and reduced chick‐provisioning to be the most commonly observed effects. Less information is available for behavioural measures, and results vary between studies. In general, small tags deployed over several days appear to have small or no measurable effect on the behavioural variables commonly observed in most guillemot tagging studies. However, there may still be impacts on fitness via physiological effects and/or reduced chick‐provisioning, while more detailed measures of behaviour (e.g. using accelerometery) may reveal effects on diving and flight performance.

生物记录装置（biologging device）能够为研究者提供野生动物在自然栖息环境中行为与活动规律的精细化观测视角。学界通常默认这类数据采集方法不会对观测到的动物行为产生干扰，然而在启动野外实地研究前，极少有调研针对鸟类可能受到的负面影响展开。兼具飞行与追逐潜水习性的海鸟，对携带生物记录装置所带来的阻力增加与载荷增重可能尤为敏感。本研究针对育雏期的成年普通海鸠（Uria aalge）开展实验：部分个体背负背载式GPS标签，另一组作为对照组不携带此类设备，标签部署时长仅为数天；所有受试个体均同步佩戴小型腿载式TDR设备（时间深度记录仪，time-depth recorder），全程记录其活动相关数据。研究人员持续监测携带设备组与对照组海鸠的体重变化以及繁殖成功率。在种群层面，所有海鸠在整个育雏周期内均出现体重下降的情况；当额外加装GPS标签后，海鸠的体重下降速率接近仅佩戴小型腿载式TDR设备时的两倍。体重下降速率的提升表明，额外加装GPS标签可能对海鸠的能量消耗或觅食能力产生了影响。尽管加装GPS标签后，海鸠的潜水表现、活动时间分配以及日常活动模式未发生显著变化，但潜水深度的分布情况出现了差异。本研究回顾了所有针对海鸠属（Uria spp.）个体佩戴标签所产生影响的相关研究，结果显示体重下降加剧与雏鸟喂食频次减少是最常被观测到的效应；目前针对行为指标的相关研究数据较为匮乏，且不同研究所得结果存在一定差异。总体而言，短期（数天）部署的小型标签，对大多数海鸠标记研究中常规观测的行为变量仅存在微弱或可忽略的影响。但此类设备仍可能通过生理层面的影响或降低雏鸟喂食效率，对海鸠的适合度产生潜在负面影响；而采用更精细的行为测量手段（例如使用加速度计技术），或可揭示标签对潜水与飞行表现的实际影响。