Nocturnal activity by the primarily diurnal Central American agouti (<i>Dasyprocta punctata</i>) in relation to environmental conditions, resource abundance and predation risk

Lambert, Thomas D.; Kays, Roland; Jansen, Patrick A.; Aliaga-Rossel, Enzo; Wikelski, Martin

doi:10.1017/s0266467408005804

Cited by 34 publications

(41 citation statements)

References 28 publications

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“…To investigate patterns of interaction between adjacent social groups, we calculated the minimum distance between the focal individual and radiocollared animals in neighbouring groups during each sampling period. Finally, we calculated the percentage of each sampling period that the animal was active based on the D signal strength between successive ARTS measurements (see Lambert et al 2009 for a description of the methods). When the orientation of a radiocollar is changed, the polarization of the antenna is also altered, changing the strength of the radio signal received by the ARTS system.…”

Section: Methodsmentioning

confidence: 99%

Does watching a monkey change its behaviour? Quantifying observer effects in habituated wild primates using automated radiotelemetry

et al. 2010

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In studies of animal behaviour, researchers have long been concerned that their presence may change the conduct of their study subjects. To minimize observer effects, researchers often habituate their study animals. The premise of this method is that, with sufficient neutral exposure, animals will stop reacting to humans. While numerous studies demonstrate that negative responses to humans decrease over time, the fact that an animal does not flee from or behave aggressively towards observers cannot be taken as evidence that it is not altering its behaviour in other, more subtle ways. Because remotely monitoring the behaviour of wild animals is difficult, it has not been possible to answer the critical question: do habituated animals change their behaviour when researchers are present? Here, we use data from an automated radiotelemetry system that remotely monitored the movement and activity of radiocollared animals to test whether observers affected the behaviour of seven habituated white-faced capuchins, Cebus capucinus. We found no evidence that observers influenced the ranging behaviour or activity patterns of their study subjects. Capuchins did not move faster, stop to rest less frequently, or display higher levels of activity when they were being followed compared to when they were alone. It has been suggested that researchers may embolden habituated study subjects, artificially increasing their relative dominance, but we found no relationship between observer presence and proximity to neighbouring social groups. Although it remains possible that observer effects existed but were too subtle to be detected with the remote sensing technology we used, the results of this study nevertheless provide reassuring evidence that humans can observe habituated wild animals without overly influencing the animals' activity and movement patterns. Ó

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Section: Methodsmentioning

confidence: 99%

Does watching a monkey change its behaviour? Quantifying observer effects in habituated wild primates using automated radiotelemetry

et al. 2010

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“…Signal strength from each transmitter was used to determine periods of inactivity, defined as any length of time, 1min or longer, during which consecutive measures of signal strength fluctuated by less than ±4dB (Kjos and Cochran, 1970;Adelman et al, 2010). The 4dB value has been calibrated in field studies and adequately represents passerine activity in the wild (Bisson et al, 2009;Lambert et al, 2009). The transmitters encoded skin temperature by varying the time interval between successive pulses.…”

Section: Radio-telemetrymentioning

confidence: 99%

Population differences in fever and sickness behaviors in a wild passerine: a role for cytokines

Adelman

Bentley

Wingfield

et al. 2010

Journal of Experimental Biology

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SUMMARYImmune responses benefit hosts by clearing pathogens, but they also incur physiological costs and tissue damage. While wild animals differ in how they balance these costs and benefits, the physiological mechanisms underlying such differential investment in immunity remain unknown. Uncovering these mechanisms is crucial to determining how and where selection acts to shape immunological defense. Among free-living song sparrows (Melospiza melodia) in western North America, sicknessinduced lethargy and fever are more pronounced in Southern California than in Washington and Alaska. We brought song sparrows from two populations (Southern California and Washington) into captivity to determine whether these differences persist in a common environment and what physiological signals facilitate such differences. As in free-living sparrows, captive California birds exhibited more pronounced fever and lethargy than Washington birds in response to lipopolysaccharide, a nonpathogenic antigen that mimics bacterial infection. After treatment, the two populations showed similar reductions in luteinizing hormone levels, food intake and body mass, although treated birds from California lost more breast muscle tissue than treated birds from Washington. Moreover, California birds displayed higher bioactivity of interleukin-6, a pro-inflammatory cytokine, and marginally higher levels of corticosterone, a steroid hormone involved in stress, metabolism and regulating inflammatory responses. Our results show that immunological differences between these populations cannot be explained by immediate environment alone and may reflect genetic, maternal or early-life effects. Additionally, they suggest that cytokines play a role in shaping immunological variation among wild vertebrates. Supplementary material available online at

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“…Agoutis shelter in multiple burrows, hollow logs, or woody debris throughout the home range (Emsens et al 2013;Smythe 1978). Agoutis are primarily diurnal, with occasional bouts of nocturnal activity (Lambert et al 2009;Smythe 1978). The ocelot is a largely nocturnal and inconspicuous felid, occurring from the southern USA to Argentina.…”

Section: Study Site and Speciesmentioning

confidence: 99%

Prey refuges as predator hotspots: ocelot (Leopardus pardalis) attraction to agouti (Dasyprocta punctata) dens

et al. 2013

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We tested the hypothesis that prey refuges attract predators, leading to elevated predator activity in the vicinity of refuges. We used camera traps to determine whether the spatial activity of a predator, the ocelot (Leopardus pardalis), was biased toward refuge locations of its principal prey, the agouti (Dasyprocta punctata). We radio-tracked agoutis at night to locate active refuges and compared the activity of ocelots between these refuges and surrounding control grid locations. We found that ocelots visited the area near agouti refuges significantly more often and for longer periods of time than control locations, and that they actively investigated the refuge entrances. Both occupied and unoccupied refuges were visited, but the duration of inspection was longer at occupied refuges. As the ocelots could probably not see the agoutis within the refuges, olfaction likely cued foraging ocelots. Two refuges were repeatedly visited by the same ocelots on different days, suggesting spatial memory. Overall, our results suggest that predators can be attracted to prey refuges or refuging prey. The benefits to prey of staying nearby a refuge would thus be counterbalanced by higher likelihoods of predator encounter. This should stimulate prey to use multiple refuges alternatingly and to not enter or exit refuges at times of high predator activity.

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Nocturnal activity by the primarily diurnal Central American agouti (Dasyprocta punctata) in relation to environmental conditions, resource abundance and predation risk

Cited by 34 publications

References 28 publications

Does watching a monkey change its behaviour? Quantifying observer effects in habituated wild primates using automated radiotelemetry

Does watching a monkey change its behaviour? Quantifying observer effects in habituated wild primates using automated radiotelemetry

Population differences in fever and sickness behaviors in a wild passerine: a role for cytokines

Prey refuges as predator hotspots: ocelot (Leopardus pardalis) attraction to agouti (Dasyprocta punctata) dens

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