Anthropogenic disturbance can negatively affect an animal’s energy budget by evoking movement responses. Existing research focuses mainly on immediate displacement as a disturbance effect, since this can be easily observed in the field. However, effects on movement over longer timescales are poorly examined and it is largely unknown if and to what extent they reflect immediate responses. Longer-term responses could for example be larger than immediate responses if birds, after disturbance, return to the original location and thereby travel twice the immediate disturbed distance. We combined GPS tracking data with observational data to quantify the effects of anthropogenic (air force and walkers) and non-anthropogenic disturbances on distances travelled by roosting Eurasian Oystercatchers (Haematopus ostralegus) during the non-breeding season. We compared immediate displacement after a disturbance with distance travelled during the entire high tide period (longer-term response), while accounting for environmental factors. Additionally, we calculated energy expenditure due to disturbance based on observed disturbance frequencies. Disturbance resulted in an immediate displacement response of ~ 200 m (median). Air force disturbances tended to yield larger immediate responses than walker and, especially, than non-anthropogenic disturbances. Longer-term responses and immediate responses were approximately similar, suggesting that, over longer timescales, spatial disturbance effects in the study area remain confined to immediate effects. However, disturbances were infrequent (0.17 disturbances per bird per hour) and most disturbances were of natural origin (62%). Consequently, anthropogenic disturbance of roosting oystercatchers in the study area on average costs 0.08% of the daily energy expenditure. Our results suggest that immediate spatial responses to disturbance can be a useful proxy for spatial responses over longer timescales. Over the non-exhaustive range of conditions investigated, energetic consequences of spatial disturbance responses for an oystercatcher in the study area are marginal due to low disturbance levels.

中文翻译：

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扰动会增加栖栖水鸟的高潮传播距离，但仅会部分影响日常能源消耗

人为干扰会引起运动反应，从而对动物的能量收支产生负面影响。现有的研究主要集中在作为干扰效应的立即位移上，因为这在现场很容易观察到。但是，对于较长时间范围内的运动影响的研究很少，而且在什么程度上以及在何种程度上反映了即时反应，目前还不得而知。如果家禽在受到干扰后返回原始位置，从而旅行了两倍于即时干扰距离，则长期响应可能会比即时响应更大。我们将GPS跟踪数据与观测数据相结合，以量化非繁殖季节人为栖息的欧亚蛎cat（Haematopus ostralegus）对人为（空军和步行者）和非人为干扰的影响。我们将扰动后的立即位移与整个高潮期的行进距离（长期响应）进行了比较，同时考虑了环境因素。另外，我们根据观察到的干扰频率计算了由于干扰引起的能量消耗。扰动会导致约200 m（中值）的即时位移响应。空军干扰往往比步行者，特别是非人为干扰产生更大的即时响应。长期反应和即时反应大致相似，这表明，在更长的时间范围内，研究区域的空间扰动效应仍仅限于即时效应。但是，干扰很少见（每只鸟每小时0.17干扰），大多数干扰是自然原因（62％）。所以，研究区人为栖息牡蛎捕捞者造成的干扰平均花费每日能量消耗的0.08％。我们的结果表明，对扰动的即时空间响应可以作为较长时间尺度上空间响应的有用代理。在所研究条件的非穷尽范围内，由于干扰水平低，研究区域内牡蛎捕捞者的空间干扰响应的高能后果是微不足道的。