Number Of Bucks Research Articles

Modeling the Impact of Climate Change on Cervid Chronic Wasting Disease in Semi-Arid South Texas.

Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission of infectious prion agents. CWD is a fatal disease that affects wild and farmed cervids in North America with few cases reported overseas. Social interaction of cervids, feeding practices by wildlife keepers and climate effects on the environmental carrying capacity all can affect CWD transmission in deer. Wildlife deer game hunting is economically important to the semi-arid South Texas region and is affected by climate change. In this paper, we model and investigate the effect of climate change on the spread of CWD using typical climate scenarios. We use a system of impulsive differential equations to depict the transmission of CWD between different age groups and gender of cervids. The carrying capacity and contact rates are assumed to depend on climate. Due to the polygamy of bucks, we use mating rates that depend on the number of bucks and does. We analyze the stability of the model and use simulations to study the effect of harvesting (culling) on eradicating the disease, given the climate of South Texas. We use typical climate change scenarios based on published data and our assumptions. For the climate indicator, we calculated and utilized the Standard Precipitation Evapotranspiration Index (SPEI). We found that climate change might hinder the efforts to reduce and effectively manage CWD as it becomes endemic to South Texas. The model shows the extinction of the deer population from this region is a likely outcome.

Examination of Annual Variation in the Adult Sex Ratio of Pronghorn (Antilocapra americana)

The adult sex ratio (ASR) is an important component of a population's demographics and can be used as an indicator of a population's status. However, the causes of annual variation in ASRs are unknown for many species. Fluctuations in ASR can arise through demographic stochasticity and intense selective harvesting. In this study we investigate the long-term patterns of variation in the ASRs (bucks: 100 does) for four populations of pronghorn (Antilocapra americana) in western Nebraska. We used multiple variables in a model selection process to predict annual fluctuation of pronghorn ASRs. We found that the number of bucks: 100 does significantly varied over the four populations. The best predictors of annual variation in pronghorn ASRs were variable across all populations. The number of pronghorn bucks harvested in the previous year's hunting season and the previous year's density of pronghorn were the most common predictors of ASR fluctuation. Buck harvest was an important predictor variable in only two of the four populations. Variation of harvest strategies within the populations could account for the lack of importance of buck harvest in half of the populations. The relationship between density and ASR is novel but difficult to interpret due to lack of data on birth sex ratios and fawn survival. More data on pronghorn demographics are needed in order to better explain the connection between density and ASR.

Assessing calf play behavior in an arena test

The use of play as an indicator of animal welfare shows promise, and an arena test is one method used to assess how different procedures or housing conditions affect calves’ motivation to perform locomotor play. However, it is unclear if this test reflects play in the home pen. In addition, the specific conditions of this test, including timing of the tests and design of the arena, vary between studies; the consequence of these differences in methodology is largely unknown. In a series of experiments, we explored the relationship between play in the home pen and arena (Experiment 1), how testing on consecutive versus alternate days (Experiment 2) and size and shape of the arena (Experiment 3) affected performance of play behavior. In all experiments running duration was continuously recorded. Additionally, the number of bucks, jumps, and kicks were recorded in the second and third experiments. On average, play in the arena reflected play in the home environment (r≥0.56, P≤0.002). However, neither play in the home pen nor the arena was consistent from day-to-day. In both the first and second experiments, frequency and duration of running were, on average, three times greater during the initial exposure to the arena than in subsequent tests, which may reflect calves’ reaction to novelty or an increase in motivation to play due to restriction in the home pen. Conducting arena tests on alternate, rather than on consecutive, days had no effect on play. In contrast, calves spent more time running in larger (60m2 vs. 30m2; ranked means: 41±3.0 vs. 32±3.0 rank of s/15min, P=0.034; true means: 19 vs. 8s/15min) and longer pens (twice the length; ranked means: 40.6±3.0 vs. 32.4±3.0 rank of s/15min, P=0.054; true means: 18 vs. 9s/15min). This is likely due to the greater distance available for uninterrupted running in the larger and longer spaces. Calves tended to jump more often in the small pens (ranked means: 40.6±3.0 vs. 32.4±3.0 rank of times/15min, P=0.066; true means: 3 vs. 2 times/15min), possibly because less space is required to perform this behavior. We found that while arena tests offer a promising tool for measuring play, caution is needed when interpreting these results, as more play is seen during the first exposure to this environment than in subsequent exposures, as well as in larger and longer arenas.

Effects of different forms of exercise on post-inhibitory rebound and unwanted behavior in stabled horses

Reasons for performing study: It is unknown if different locomotor activities are equally effective at meeting the stabled horse's need for exercise and if they attenuate unwanted behaviour. Hypothesis: Alternative forms of exercise influence the intensity of locomotor activities during a period of turn-out (the so-called rebound effect) and the occurrence of unwanted or undesirable activities during standard handling situations. Method: Twenty-four horses kept in stables were randomly assigned to one of 4 exercise regimes (walker, treadmill, turn-out and riding) for 4 consecutive days. Because these forms of exercise provide additional environmental stimulation, beyond that provided by exercise, each horse served as its own control in 4 corresponding (no exercise) control treatments presented in a balanced order. Unwanted behaviour was tested by taking horses to weighing scales and loading and unloading them onto a 4-horse float by an experienced handler and the rebound effect was tested by releasing them into a large arena for a period of 15 min at the end of the exercise and control treatments. Results: Locomotor activities made up a large part of behaviour in the large arena following control treatments and all exercise regimes were sufficient to reduce the intensity of walking (P<0.05), trotting (P<0.01) and cantering (P<0.001) on release into a large arena. Exercise regime reduced the number of bucks (P<0.01) and rolling (P<0.05) during rebound tests suggesting that turn-out was having a stronger effect than the other 3 exercise regimes. Exercise regimes significantly reduced the amount of unwanted behaviour and the number of commands given by the handler during weighing (P<0.05) but had no effect on these behaviours during loading onto a float. Conclusion: Providing stabled horses with one hour/day of exercise on a walker, treadmill, turn-out or by being ridden are all effective at allowing expression of locomotor activities in stabled horses. Potential relevance: Providing stabled horses with regular exercise is likely to provide positive effects on horse welfare, training ability and handler safety.

A classification scheme to better understand satisfaction of Black Hills deer hunters: The role of harvest success

This research applies the multiple satisfactions concept in segmenting hunters to gain a better understanding of the relationship between harvest success (harvesting a doe or a buck) and satisfaction. South Dakota Black Hills deer hunters were segmented into seven types (nature, social, excitement, meat, trophy, solitude, and exercise) based on their main reason for liking to hunt deer in the Black Hills. Exercise hunters were dropped from further analyses due to small segment size. Next, the simple relationship between harvest success and satisfaction was explored for each hunter type. Harvest success proved to have a relationship to satisfaction that differed for the different types of hunters. This analysis was followed by an exploration of the linear relationship of harvest success and satisfaction with seven other variables to determine the best predictors of satisfaction for each of the hunter types. Hunters’ subjective evaluations of the number of deer seen, number of bucks seen, and buck quality had a higher correlation with satisfaction than actual harvest success.