Mammal Study

In order to investigate the relationship between limb bone internal structure and the aquatic adaptation, we examined humeri of multiple carnivoran species of various lifestyles (terrestrial, semiaquatic, and aquatic) using micro-focus CT scanner. The transverse section image passing through the inferred center of ossification is analyzed in order to estimate the structural remodeling in periosteal bone. Meanwhile, structural characteristics in sagittal section images of proximal end were described in order to assess the characteristics in endochondral bone. The degree of cancellousness around the center of ossification, which is interpreted as the amount of resorption in periosteal compact bone, is the lowest in the semiaquatic group and the highest in terrestrial groups. This suggests that the ratio of periosteal bone resorption in limb bones decreases in the first stage of the aquatic adaptation, possibly due to the less need for skeletal lightening in semiaquatic taxa than the terrestrial taxa, and then increases as the limb bones reduces their support function on land, presumably in relation to the deep diving. The bone trabecular architecture in humeral head is fine and well-oriented in terrestrial to semiaquatic carnivorans, while that of aquatic carnivorans is rather coarse and randomly oriented.

Information on activity profile of the Ganges river dolphin (Platanista gangetica gangetica) and its responses to human interference were lacking. A study following focal animal sampling protocol with individual-follow method and assessment of human interference on dolphin occurrence and behavior was hence conducted. Based on logical reasoning and prior assumptions, dolphin activities were broadly categorized into four types viz., surfacing, movement, chasing/feeding and underwater. Percentage frequencies of occurrence of these activities in dolphin activity budget were 50%, 26%, 6% and 18% with corresponding time allocations of 1%, 60%, 4% and 35%, respectively; without any significant difference between male and female activity patterns (χ² = 0.832, df = 3, P > 0.05). Five different modes of surfacing were observed with dive-times ranging from 4 to 504 sec and average prey chase-time of 38 (SD = ±29) sec. Human interference had a negative relationship with dolphin presence (β = -0.6398, z = -3.816, P < 0.001). All recorded dolphin activities showed a positive relationship with human presence except underwater activity (β = -0.1115, z = -3.76, P < 0.001). Detailed behavioral study and proper check on increasing anthropogenic influence is necessary to ensure the species safe survival.

Wild canid foraging behaviour and regional abundance are often affected by the availability of anthropogenic food, supplementing natural diet. The feeding habitats of the golden jackal (Canis aureus) were compared between two populations in central Bulgaria, for which food availability and the extent of anthropogenic-modified habitat differed. Stomach contents were collected from hunting bags during winters from 1997 to 2009 and compared between an agriculturalhilly region (Region 1) and a forested-mountainous region (Region 2). Although mammalian prey predominated in the jackal's diet in the two regions, diets differed significantly between the regions: in Region 1 the main foods were domestic animals (30.2%), while in Region 2 wild ungulates proved to be the dominant food type (47.9%). We propose that although regional differences in jackal foraging habits were apparent between the two regions, foods originating from human activities were important in both regions. In Bulgaria, the golden jackal is regarded as a nuisance pest, requiring population control. Managing the availability of anthropogenic food sources to jackals, e.g., carcasses of wild and domestic animals, may implicitly reduce jackal abundance and/or discourage jackals from foraging around sites occupied by people.

Camera trap method has been developed for monitoring wildlife, however, most studies using camera trap depend on baited camera sites to attract target wildlife. This is likely to bias estimates of population structure. We evaluated the use of non-baited camera trap for the estimation of herd composition of sika deer (Cervus nippon). Camera trap showed a distinct seasonal pattern in sex ratios (males/100 female), which remained lowest between May and October but increased in November. Sex ratios were influenced by the number of observed males, because the ratios were positively correlated with the number of males but not females. The number of males increased in autumn during rutting season. Fawns/100 female ratios showed a distinct seasonal pattern. Highest and lowest fawns/100 female ratios were obtained in November and May, respectively. The decrease of fawns/100 female ratios in May comparing with that in November may be because of the overwinter mortality of fawns. Camera trap method is superior in term of continuously conduct in long-term, collect reasonable seasonal patterns, automatically record large numbers of sample sizes and useful in all weather conditions.