Browsing by Subject "Aggressive behavior in animals"
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Item Aggression and habitat segregation among diving ducks wintering in South Carolina(Texas Tech University, 1986-12) Bergan, James FAggression and habitat segregation among buffleheads (Bucephala albeola), lesser scaup (Aythya affinis), ring-necked ducks (Aythya collaris), and ruddy ducks (Oxyura jamaicensis) were investigated in 1985 and 1986, on Par Pond, South Carolina. A total of 4,567 focal individuals were sampled during 384 hours with nearly equal representation of species and sexes. Intraspecific aggression was infrequent (N=69). Interspecific aggression accounted for 228 observations which included American coots (Fulica americana) and pied-billed grebes (Podilymbus podiceps). The ring-necked duck was most aggressive (^=62 intra- and interspecific encounters). Time spent in aggressive activity was less than 1% for all species. Habitat availability - use analysis determined that both inter- and intraspecific habitat segregation occurred over 4 habitat types. Segregation, in the absence of an appreciable amount of aggression, suggests that the inter- and intraspecific dominance hierarchies, as reported among other wintering waterfowl assemblages, do not exist among species in this study. Time-activity analysis indicated that foraging was the most important activity for all species. Buffleheads foraged more than any of the other species. Courtship behavior was exhibited often by buffleheads, and more infrequently by ring-necks. Among lesser scaup and ring-necked ducks females spent more time foraging and less time resting/sleeping than did males. Time spent foraging by buffleheads, lesser scaup, and ring-necked ducks increased throughout the winter. The aforementioned diurnal activity trends were also detected during nocturnal hours. However, foraging time was lower for all species except ruddy ducks, which actively fed at night. Diel feeding activity peaks varied by species but in general, most feeding occurred during the late night (0230 - sunrise), early morning (sunrise - 1030), and midday (1030 - 1430) periods. Behavior investments also varied by location. At the Cold Dam site, time spent in locomotion was highest while feeding time was generally less for each species relative to the other two locations. Variation between diurnal and nocturnal time budgets illustrates the importance of considering the entire 24-hour cycle of wintering waterfowl behavior rhythms. In addition, spatial differences in behavior indicate that variation can occur between sites. Measured weather variables accounted for little variation in behavioral investments.Item Effects of altrenogest on sexual/aggressive behavior, hormonal profiles, and testicular parameters in young stallions(Texas Tech University, 1997-08) Johnson, Nikki NikoleNot availableItem Effects of short-term oral altrenogest dosages on behavioral and testicular parameters of post-pubertal stallions(Texas Tech University, 2000-12) Vartorella, Heather A.Overly sexual/aggressive stallions within the performance horse industry create a hazardous working environment and several training challenges To suppress these behaviors without surgical castration, many trainers are currently administering oral altrenogest (Regu-Mate®, Intervet International B V., Boxmeer, Netherlands) to stallions in an off-label apphcation. Though few studies have been performed on stallions, previous work suggests the effectiveness of altrenogest in reducing the levels of reproductive hormones, spermatogenesis, and sexual/aggressive behavior varied depending on the dosage size, the duration of treatment, and the age of the stallion. However, to date no one has examined the efficiency of a short term, repetitive dosage with practical application, such as when behavior is unwanted only for a temporary period (during a performance presentation; i.e., show or race). Therefore, the objective of this study was to evaluate the testicular, hormonal, and behavioral parameters of three year old stallions receiving a short term, repetitive dosage of oral altrenogest. Further objectives were to etermine if the sexual/aggressive behavioral could be suppressed while reducing the longterm negative effects on reproduction. Nine, three-year-old Quarter Horse stallions were initially blocked by sire, and then randomly designated to two groups, treatment (n=5) and control (n=4). The treatment group received an oral daily dose of 0.088 mg/kg BW Regu-Mate® followed by ten days of recuperation (no treatment). This process was repeated for a total of three times over 60 days, followed by a recovery period of 36 days. The altrenogest dosages had no significant effects on body weight, but did increase body condition scores (P=0.052). Body condition scores remained higher after Day 30. Of the testicular parameters analyzed on Day 96, scrotal width and gross testicular parameters were unaffected, however, mean spermatid counts were decreased (P<0.05). While no differences were due solely to treatment for either estrogen or testosterone concentrations, there was a significant time by treatment interaction involving estrogen levels(P<0.05). No significant differences were seen for any of the behavioral actions analyzed based on frequency, latency, or duration, at any point of the study. Several traits assessed in this study showed large variations between individual stallions. Further research of altrenogest in the stallions is needed to determine a practical dosage amount and sequence to produce a manageable animal, which takes age and fertility effects into consideration.Item Social experience, hormones and aggressive behavior in the green anole lizard (Anolis carolinensis)(2002-08) Yang, Eun-jin; Wilczyński, WDifferences in individuals’ social experiences make an important contribution to individual differences in the expression of social behavior. Here I report the influence of recent social experience on aggressive behavior in the green anole lizard, Anolis carolinensis. Green anoles have distinct and highly stereotypical social displays that occur during territorial aggressive encounters. However, certain territorial owners act more aggressively than others. This dissertation reports a series of experiments based on the observation that a short period of aggressive social experience can facilitate subsequent aggressive behavior in this species, and the idea that gonadal hormones acting on limbic and hypothalamic nuclei in the brain mediate this experience-dependent facilitation of social behavior. I found that exposure to a video clip of an aggressively displaying conspecific male, for one ten-minute period each day for five days caused male anoles to become more aggressive toward a subsequent conspecific challenger, compared to animals exposed to a video clip showing two moving balls. During the video exposure period, animals showed a robust behavioral pattern of an initial rise followed by dramatic decreases in aggressive responses toward the aggressive video. Plasma testosterone concentrations measured using radioimmunoassays during the 5 days of social encounters showed a pattern similar to that of aggressive behavior. Using structural equation modeling to examine the causal relationships underlying this synchrony of endocrine and behavioral responses suggested that it was the experimental animals’ behavior in response to the stimulus that caused increased testosterone secretion, more probably than the contrary. Unlike testosterone or behavioral responses, plasma corticosterone levels in animals encountering aggressive conspecifics were high throughout the 5-day encounter period. When corticosterone synthesis was blocked temporarily during stimulus exposure, animals did not show decreases in behavioral responses to the stimulus in later exposures, suggesting that corticosterone is involved in behavioral habituation. Finally, I found that metabolic activity, indicated by levels of cytochrome oxidase activity, in Septum, Amygdala, Nucleus Accumbens, Preoptic area, and nucleus Rotundus was upregulated following exposure to the aggressive video for five days, suggesting that these areas are involved in processing this social experience, and in the observed experience-dependent facilitation of aggressive behavior.Item The effects of oral altrenogest on two-year-old stallions in training(Texas Tech University, 1999-12) Heninger, Noah L.Despite widespread use of oral altrenogest (Regu-Mate®, Hoescht-Roussel Vet, Warren, NJ) by trainers throughout the performance horse industry to suppress sexual/aggressive behavior in the stallion, few studies have been performed to document both short and long term physiological effects. Further, variable doses of altrenogest are currentiy in extra-label use, including 0.044mg/kg BW per day (current label dose for the suppression of estrus in mares) and 0.088 mg/kg BW per day. This study examined the suppressive effects of the single mare dose of altrenogest (0.044 mg/kg BW daily) on the steroidal hormone profiles, seminal quality, and sexual/aggressive behavior in two-yearold stallions. Ten two-year-old Quarter Horse stallions in early training were exercised in a training protocol consistent with methods to produce a working ranch horse. Prior to the study, horses were put through a training period for semen collection behavior. Horses were stratified across treatments according to breeding performance and sire, then randomly assigned to treatment (n=5) and control (n=5) groups. The treatment group was administered a daily oral dose of 0.044 mg/kg BW daily for a period of 67 days. No significant differences were found between treatment groups in weight or body condition scores at the experimental dose given. Altrenogest also had no significant effect on any behavioral parameters measure by standardized teasing tests or at time of semen collection. No significant differences were seen for any seminal parameter, at any point in this study. Averages of total scrotal width (TSW) across control and treatment groups were lower (P<. 03) for treatment animals at the end of treatment time period (d 67). By day 157 mean TSW for both treatment and control stallions were not different from each other; however, both were significantiy higher from pre-trial and end of treatment period values. At castration, comparisons of trimmed testicular weight (testicle minus the epididymis) between control and treatment groups were not different. Histological analysis of testicular tissue revealed no significant difference between treatment groups for the average number of spermatids per seminiferous tubule. Altrenogest treatment significantly reduced serum level estrogen (estradiol 17-P) by day 67. Estrogen levels remained suppressed (P = .02) after three months of recovery in these treatment animals. There were no effects on serum testosterone levels throughout the trial. Data from the current study suggest that a daily dose of 0.044 mg/kg BW of altrenogest suppressed estrogen production and scrotal width in the two-year-old stallions, however, stallion sexual/aggressive behavior and seminal parameters were not significantly affected by treatment. This study also showed large variation in libido and sexual/aggressive behavior between these young stallions. Further research is needed to determine various doses and age effects of altrenogest in the stallion.