Abstract
Simple SummaryChange in an animal’s behavior due to anthropogenic influences is often expressed in a change in movement patterns and increased vigilance and can result in the secretion of stress-related hormones. However, animals can get habituated to human presence after repeated stimulation. We aimed to obtain a first insight into the effect of human observers on the behavior and stress-related hormone concentrations of free-roaming giraffes as well as their habituation process. Giraffes walked further distances and had elevated fecal glucocorticoid metabolite (fGCM) concentration (stress hormone) in the presence of humans, but anthropogenic influences on their distance walked and fGCM concentration decreased with the increase of habituation. The giraffes were vigilant towards human observers; however, the percentage of time spent on observing a human observer did not decrease with the increase of habituation. Giraffes are an important tourist attraction, and human presence to wildlife is increasing. This has an impact on an animal’s behavior and its endocrine correlates. Studies on other species show alterations in movement patterns, vigilance, and stress-related hormone levels in the presence of humans. Limited information is available on how anthropogenic activities alter giraffe’s behavior, social structure, and related endocrine parameters. The purpose of this study was to obtain insight into anthropogenic influences on giraffe’s behavior and adrenal activity. We used GPS devices mounted onto giraffes to compare the distance walked in the presence or absence of human observers. We also conducted behavioral observations to assess their vigilance and collected fecal samples to analyze their fecal glucocorticoid metabolite (fGCM) concentrations. Giraffes walked significantly further distances in the presence of humans, but the cumulative time that observers were present decreased the hourly distance walked with an observer present, suggesting that the giraffes were becoming habituated. The number of observers present significantly increased the percentage of time spent on observing an observer as well as the number of unhabituated individuals present in the herd. The percentage of time spent observing a human observer did not decrease with the increase of habituation. Last, fGCM concentrations increased with human presence but decreased when individuals became habituated to human presence. More research is needed to understand the effect of anthropogenic influences in different scenarios (e.g., tourism, vehicles, hunting, etc.).
Highlights
Behavioral ecology studies where observers are present often rely on habituated focal individuals or groups [1]
It is known that fecal glucocorticoid metabolite (fGCM) concentrations can differ between males and females [16]; sex was added as a fixed factor
The final model included only these factors of interest: human observers present, the cumulative time of observer present, and sex, added as fixed factors, as well as individual as a random factor. Possible control variables, such as distance walked, season, rain, and temperature were found to be insignificant in the presence of the factors of interest, and including them in the model resulted in higher Akaike Information Criterion (AIC) values; we report the model without those control variables
Summary
Behavioral ecology studies where observers are present often rely on habituated focal individuals or groups [1]. Habituation can cause changes to an animal’s behavioral patterns and physiological status [7]. Human presence can change the vigilance behavior and potentially the social structure of animals who live in groups [3,9]. Wildlife viewing of polar bears (Ursus maritimus) in Canada influence the bear’s vigilance behavior [10], and human observers and settlements influence samango monkey’s (Cercopithecus mitis erythrarcus) [1] and giraffe’s (Giraffa camelopardalis) [11] movement patterns and prey–predator relationships
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