Applied Animal Ethology最新文献

Social organisation was studied in a herd of Père David's deer (Elaphurus davidianus) at Chester Zoo. Aggression shown by the oldest male to females and younger males occurred throughout the year, but peaked during and just after the rut. Some female aggression to other females was evident throughout the year, and to the younger males just after the rut. Associated sexual behaviour of the males included grass-thrashing with the antlers, roaring and flehmen.

There is obvious confusion in the literature on pig vocalizations. It is not clear whether pig calls are discrete or continuous in form and function, and whether they are specific signals. The aim with this study was to try to classify piglet vocalizations uttered during nursing, and the hypothesis was that the sounds are, in fact, structurally discrete. All vocalizations uttered during 33 nursings in 3 litters during 3 days after farrowing were recorded, and 106 sounds were processed in a spectrograph. The spectrograms were analysed by the following method. Firstly, they were classified in groups on the basis of a number of physical parameters which were quantified for each spectrogram. Secondly, the inter-class dissimilarity was tested with single-link cluster-analysis. Thirdly, the correlation of the physical parameters was tested within classes with correlation and regression calculations. The analysis supported the existence of 5 discrete classes of piglet vocalizations: croaking; deep grunt; high grunt; scream; and squeak. In croaking, scream and squeak there was a correlation between basic frequency and time, indicating a continuous variation of intensity within the discrete call classes. It was further concluded that any viewpoint on the function of the sounds must be based on studies of statistical links between specific signals and certain behaviour in the receiver.

The involvement of light in nest-site selection by domestic fowls was tested in two strains of laying hens at two stages of maturity. Individuals that were about to lay an egg were isolated in a pen and given a choice of two sorts of nest-box, one illuminated internally and the other without illumination. Nearly all birds tested laid in one of the boxes provided, but their choice of dark or light conditions varied strongly with both strain and maturity. Only one of the four categories of hen, those of a White Leghorn strain laying their first egg, exhibited the expected preference for dark nests. Birds of a strain derived from Rhode Island Reds were more likely to lay in light nests, and with both strains hens which had previously been laying in open pens showed greater preference for light nests than did naïve individuals. These results suggest that light intensity is not a fundamental factor influencing nest-site selection, but it may nevertheless haveto be considered in the management of laying hens.

The peck orders of chickens have been measured in many ways, and the question of which measure is most appropriate arises. This can only be answered in reference to the way that the measure is to be used. Staging paired contests between unacquainted birds is best used to assess the stable, intrinsic traits that underly dominance relationships. However, this method does not give reliable estimates of the relationships the birds form when grouped. The social environment of each bird is best assessed by observing the agonistic encounters that occur. However, the comparability of the different forms of aggressive behaviour needs to be established. Measures based upon priority of access to food cannot be used with confidence. Measures of rank need to be normally distributed and reflect the actual magnitude of the difference between birds only when these are to be used in assessing the underlying traits.

Length of time spent in an activity can be estimated by observations at fixed time-intervals. By illustration with 3 sets of data, this report shows that the formula proposed by Mullen et al. in 1980 substantially under-estimates the accuracy of estimation for grazing time.

The experiment was designed to test the hypothesis that social interaction between rams influenced their serving capacity and modified their preference for ewes.

The serving capacity and the preference for particular ewes was recorded on the first and seventh day of joining in 8 rams mated either individually or in pairs to 12 oestrous ewes. The serving capacity (mean number ejaculates/hour) was 50% lower in both dominant and submissive rams when working together compared with single-sire matings. However, when working together, 33% of the available ewes were served by the submissive ram and 12.5% were served by the dominant ram so that, in total, more ewes were served (total mean number ± SE of ewes served/ram when mated either individually or as a pair = 4.50 ± 0.89 and 5.50 ± 0.57, respectively). This resulted from a modification in ewe preference by the submissive ram.

In the absence of competition, the same ewes were observed to be preferred by most rams. This ewe “attractiveness” was found not to be a permanent characteristic, as the preferred ewes at one oestrus were not necessarily those most preferred at a subsequent oestrus.

Two groups each of three fattening pigs were used. After the rank order had been determined, the animals in each group were deprived of food for 12 hours. One was then left in the experimental room, given food ad libitum, and allowed to eat to satiation. Within 10 minutes of having stopped feeding, one of the others from its group was put in the adjacent stall and allowed to feed. In all cases, the apparently satiated pig started to feed when the newly-introduced pig started to feed. When used as the remaining pig, the dominant pig in each group fed for longer and ate more than the other-ranking pigs when a hungry pig was introduced into the next-door stall. In order to test whether the resumption of feeding was due to the cessation of isolation or due to the feeding behaviour of the introduced pig, a second experiment was performed. The same groups were used plus another group of three similar pigs. After 12 hours of food deprivation, two pigs were left in adjacent stalls and allowed to feed until satiated. The third member of their group was then introduced and allowed to feed in a stall facing the other two. In all cases the remaining pair fed for appreciable periods. These results confirm that social facilitation, as defined here, occurred in the feeding behaviour of these pigs.

The feeding behaviour of 4 castrated boars was studied over 24 hours using a photoelectric cell and continuous recorder at 4 body-weight stages, viz. 20, 40, 60 and 80 kg. Two of the pigs were on continuous light, and 2 were on 8.5 h light and 15.5 h of darkness. The 2 pigs in each treatment were in adjacent stalls but well separated from the other pair and other pigs. There were no differences in total food consumption between the animals in the 2 treatments. Eating speed also did not differ between treatments; neither did it differ between body-weight stages when adjusted for body weight. The percentage of the total time devoted to feeding differed between body-weight stages but not between treatments. However, over the first 8-h period of the day, the pigs on the short day-length spent more time feeding, but body weight did not affect this measure. Meal intervals were determined by a logarithm survivorship curve analysis, and it was found that pigs on the long day-length had significantly more meals than the others. Body weight also affected the number of meals, with the youngest taking most. Furthermore, both pairs showed a significant degree of synchronized feeding.