The Effects of Human Age,Group Composition,and Behavior on the Likelihood of Being Injured by Attacking Pumas

ABSTRACT

Documentation from the years 1890 to 2000 of 185 instances of pumas (Puma concolor) attacking humans in the United States and Canada has provided statistical evidence that pumas are less likely to kill or injure humans in certain circumstances. We identified incidents of fatal attacks, severe injuries, light injuries, and no injuries as a function of human age class, group size, body posture, and conspicuous action, such as noise making, running, or shooting. Ordinal multinomial regression revealed that age class (< 13 years old vs. older) was not a statistically reliable predictor of attack severity. This statistical method also revealed that there was no reliable association between the number of individuals present during the attack and attack severity. Nevertheless, examination of specific attack outcomes indicated that the likelihood of escaping injury increased when two or more people were present. The speed that individuals moved during the attack did not predict attack severity, but it was apparent that the lowest likelihood of escaping injury (26%) and greatest frequency of severe injuries (43%) occurred when individuals remained stationary. In contrast, half of the individuals who ran when they were attacked escaped injury, whereas running was associated with only a small increase in the frequency of fatal attacks (28%), compared with remaining stationary (23%). Evidence that half of the individuals who ran escaped injury suggests that pumas are assessing immobility in humans as they might with other prey, using it as an index of prey inattention or disablement and hence greater vulnerability.     

Cost of mobbing call to breeding pied flycatcher, Ficedula hypoleuca

Mobbing signals advertise the location of a stalking predatorto all prey in an area and recruit them into the inspectionaggregation. Such behavior usually causes the predator to moveto another area. However, mobbing calls could be eavesdroppedby other predators. Because the predation cost of mobbing callsis poorly known, we investigated whether the vocalizations ofthe mobbing pied flycatcher, Ficedula hypoleuca, a small holenesting passerine, increase the risk of nest predation. We usedmobbing calls of pied flycatchers to examine if they could lurepredators such as the marten, Martes martes. This predator usuallyhunts by night and may locate its mobbing prey while restingnearby during the day. Within each of 56 experimental plots,from the top of one nest-box we played back mobbing sounds ofpied flycatchers, whereas blank tapes were played from the topof another nest-box. The trials with mobbing calls were carriedout before sunset. We put pieces of recently abandoned nestsof pied flycatchers and a quail, Coturnix coturnix, egg intoeach of the nest-boxes. Nest-boxes with playbacks of mobbingcalls were depredated by martens significantly more than werenest-boxes with blank tapes. The results of the present studyindicate that repeated conspicuous mobbing calls may carry asignificant cost for birds during the breeding season.     

Stability and change in the vocal signatures of common marmoset mobbing calls

Alarm calls that carry information about the identity of the caller may help the receiver decide how to react. We recorded the tsik calls of six captive adult marmosets (Callithrix jacchus) in two different social groups in response to snake models at two time points (summer 2014 and January 2015). We measured eight acoustic variables including duration, inter-call interval, minimum and maximum frequency, and starting, maximum and ending peak frequency. Discriminant function analyses (DFA) confirmed that calls were individually distinct at both time periods (78.88 and 79.89% correctly classified at time one and time two, respectively). Stability of the vocal signatures was assessed using the DFA model for summer 2014 to classify calls elicited in January 2015. Although the classification rates were lower in 2015, calls were still classified more than would be expected by chance (64.50%). This suggests that acoustic signatures of common marmoset tsik calls remain fairly stable over time and therefore remain recognizable by their groupmates. However, during that six-month period, at least three (out of seven) acoustic parameters changed such that they were significantly higher or lower in all six marmosets; in two marmosets six out of seven parameters changed. Changes to individual ‘voices’ of animals, despite overall stability reflected in above-chance matching of calls over time in a DFA analysis, may have implications for acoustic research.