摘要: Vocal communication is a crucial aspect of animal behavior. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered by the geometry and length of the upper vocal tract. Evidence from mammalian anatomy and bioacoustics suggests that some of these three components may covary with an animal's body size. The framework provided by acoustic allometry suggests that, because vocal tract length (VTL) is more strongly constrained by the growth of the body than vocal fold length (VFL), VTL generates more reliable acoustic cues to an animal's size. This hypothesis is often tested acoustically but rarely anatomically, especially in pinnipeds. Here, we test the anatomical bases of the acoustic allometry hypothesis in harbor seal pups Phoca vitulina. We dissected and measured vocal tract, vocal folds, and other anatomical features of 15 harbor seals post-mortem. We found that, while VTL correlates with body size, VFL does not. This suggests that, while body growth puts anatomical constraints on how vocalizations are filtered by harbor seals' vocal tract, no such constraints appear to exist on vocal folds, at least during puppyhood. It is particularly interesting to find anatomical constraints on harbor seals' vocal tracts, the same anatomical region partially enabling pups to produce individually distinctive vocalizations.

摘要: It is proposed that where sexually selected vocal communication is an honest signal, the call production rate is predicted to change throughout the breeding season. Male leopard seals call underwater for many hours each day over their three-to four-month breeding season, and it is hypothesized that a decrease in calling rate would be associated with the declining body condition of smaller males. The calling rates of leopard seals were measured (N = 49 recordings) and compared between seals of different size classes throughout the breeding season. Male leopard seals produce their calls at more stable rates as they become larger. In this study, larger male leopard seals adopted a strategy of consistent underwater calling throughout the breeding season, whereas there was a breakdown in the calling stereotypy of the smaller males at its height. Toward the end of the breeding season, the smaller seals produced fewer calls in shortened calling bouts, and they took more rest periods. Therefore, underwater calling may represent an honest signal in the leopard seal. For marine mammals that call underwater, the production of repetitive sequences advertises the breath-holding ability of the caller to the listeners, and this ability may be related to male stamina and endurance, thus representing an honest signal that could be widespread in other species.

摘要: The wild population of the African lion Panthera leo continues to decline, requiring alternate conservation programs to be considered. One such program is ex situ reintroduction. Prior to release, longterm monitoring and assessment of behavior is required to determine whether prides and coalitions behave naturally and are sufficiently adapted to a wild environment. Social network analysis (SNA) can be used to provide insight into how the pride as a whole and individuals within it, function. Our study was conducted upon 2 captive-origin prides who are part of an ex situ reintroduction program, and 1 wild pride of African lion. Social interactions were collected at all occurrence for each pride and categorized into greet, social grooming, play, and aggression. Betweenness centrality showed that offspring in each pride were central to the play network, whereas degree indicated that adults received (indegree) the greatest number of overall social interactions, and the adult males of each pride were least likely to initiate (outdegree) any interactions. Through the assessment of individual centrality and degree values, a social keystone adult female was identified for each pride. Social network results indicated that the 2 captive-origin prides had formed cohesive social units and possessed relationships and behaviors comparable with the wild pride for the studied behaviors. This study provided the first SNA comparison between captive-bred origin and a wild pride of lions, providing valuable information on individual and pride sociality, critical for determining the success of prides within an ex situ reintroduction program.

摘要: RGB displays effectively simulate millions of colors in the eyes of humans by modulating the relative amount of light emitted by 3 differently colored juxtaposed lights ( red, green, and blue). The relationship between the ratio of red, green, and blue light and the perceptual experience of that light has been well defined by psychophysical experiments in humans, but is unknown in animals. The perceptual experience of an animal looking at an RGB display of imagery designed for humans is likely to poorly represent an animal's experience of the same stimulus in the real world. This is due, in part, to the fact that many animals have different numbers of photoreceptor classes than humans do and that their photoreceptor classes have peak sensitivities centered over different parts of the ultraviolet and visible spectrum. However, it is sometimes possible to generate videos that accurately mimic natural stimuli in the eyes of another animal, even if that animal's sensitivity extends into the ultraviolet portion of the spectrum. How independently each RGB phosphor stimulates each of an animal's photoreceptor classes determines the range of colors that can be simulated for that animal. What is required to determine optimal color rendering for another animal is a device capable of measuring absolute or relative quanta of light across the portion of the spectrum visible to the animal ( i.e., a spectrometer), and data on the spectral sensitivities of the animal's photoreceptor classes. In this article, we outline how to use such equipment and information to generate video stimuli that mimic, as closely as possible, an animal's color perceptual experience of real-world objects.

摘要: We tested whether continuous cohabitation in monogamous voles affects the mated male's attentiveness to his breeding partner versus another female. Each male was housed in a 3-chamber apparatus with a Focal female (FF) and a Control female (CF) for 13 days then placed in a T-maze to assess his attentiveness to and memory of those females. The Distal male remained physically separated from both females, but received their distal cues. The Separate male cohabited with the FF for 3 days then remained physically separated from both females. The Disrupt male's continuous cohabitation with the FF was disrupted by having him physically separated from her after 10 days and placed with the CF for the last 3 days. The Continuous male cohabited continuously with the FF for 13 days. With females in the T-maze, the Separate and Disrupt males spent more time near the FF's box and the Disrupt males spent more time manipulating the FF's box than the CF's box. The Separate males groomed themselves more when near the FF's box than the CF's box. The Distal and Continuous males' attentiveness to the two females did not differ. Results suggest that physical distance from the partner may reduce male's attentiveness toward other potential mates. Prairie voles might be similar to socially monogamous primates in using tactile cues as a signal for maintaining their social bonds.