Hernani Lineros Lucero M, Chimènes Amélie, Maille Audrey, Dingess Kimberly, Rumiz Damián I, Adret Patrice
Zoología Vertebrados, Museo de Historia Natural Noel Kempff Mercado, Santa Cruz de la Sierra, Bolivia.
Carrera de Biología, Universidad Mayor de San Andrés, La Paz, Bolivia.
PeerJ. 2020 Nov 20;8:e10417. doi: 10.7717/peerj.10417. eCollection 2020.
Worldwide urban expansion and deforestation have caused a rapid decline of non-human primates in recent decades. Yet, little is known to what extent these animals can tolerate anthropogenic noise arising from roadway traffic and human presence in their habitat. We studied six family groups of titis residing at increasing distances from a busy highway, in a park promoting ecotourism near Santa Cruz de la Sierra, Bolivia. We mapped group movements, sampled the titis' behavior, collected fecal samples from each study group and conducted experiments in which we used a mannequin simulating a human intrusion in their home range. We hypothesized that groups of titi monkeys exposed to higher levels of anthropogenic noise and human presence would react weakly to the mannequin and show higher concentrations of fecal cortisol compared with groups in least perturbed areas. Sound pressure measurements and systematic monitoring of soundscape inside the titis' home ranges confirmed the presence of a noise gradient, best characterized by the root-mean-square (RMS) and median amplitude (M) acoustic indices; importantly, both anthropogenic noise and human presence co-varied. Study groups resided in small, overlapping home ranges and they spent most of their time resting and preferentially used the lower forest stratum for traveling and the higher levels for foraging. Focal sampling analysis revealed that the time spent moving by adult pairs was inversely correlated with noise, the behavioral change occurring within a gradient of minimum sound pressures ranging from 44 dB(A) to 52 dB(A). Validated enzyme-immunoassays of fecal samples however detected surprisingly low cortisol concentrations, unrelated to the changes observed in the RMS and M indices. Finally, titis' response to the mannequin varied according to our expectation, with alarm calling being greater in distant groups relative to highway. Our study thus indicates reduced alarm calling through habituation to human presence and suggests a titis' resilience to anthropogenic noise with little evidence of physiological stress.
近几十年来，全球范围内的城市扩张和森林砍伐导致非人灵长类动物数量迅速减少。然而，对于这些动物能够在多大程度上容忍其栖息地内道路交通和人类活动产生的人为噪音，我们却知之甚少。我们在玻利维亚圣克鲁斯德拉谢拉附近一个促进生态旅游的公园内，研究了六组伶猴，它们居住的地方离一条繁忙的高速公路越来越远。我们绘制了猴群的活动轨迹，对伶猴的行为进行采样，从每个研究组收集粪便样本，并进行了实验，在实验中我们使用了一个模拟人类侵入其活动范围的人体模型。我们假设，与受干扰最小地区的猴群相比，暴露于更高水平人为噪音和人类活动的伶猴群对人体模型的反应较弱，且粪便皮质醇浓度更高。对伶猴活动范围内的声压测量和对声景的系统监测证实了噪音梯度的存在，用均方根（RMS）和中值幅度（M）声学指数来描述最为合适；重要的是，人为噪音和人类活动是共同变化的。研究组生活在小范围且相互重叠活动区域内，并将大部分时间用于休息，它们在移动时优先使用较低的森林层，觅食时则使用较高的森林层。焦点抽样分析显示，成年猴对移动时间与噪音呈负相关，行为变化发生在44分贝（A）至52分贝（A）的最小声压梯度范围内。然而，对粪便样本进行的有效酶免疫分析检测到皮质醇浓度低得出奇，与RMS和M指数的变化无关。最后，伶猴对人体模型的反应符合我们的预期，远处猴群相对于高速公路的报警叫声更大。因此，我们的研究表明，通过对人类活动的习惯化，报警叫声减少，这表明伶猴对人为噪音具有恢复力，几乎没有生理压力的迹象。
