Abstract: Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such cases, distinguishing between kin and non-kin, and investing only in the former (nepotism), can be advantageous. Bluegill sunfish ( Lepomis macrochirus) are characterized by paternal care and cuckoldry, and care-providing males appear to show nepotistic behaviours. Here, we investigated nestling recognition in bluegill, determining whether parental males can differentiate between young from their own nest (familiar and related) and young from non-neighbouring nests (unfamiliar and unrelated) using (1) visual and chemical cues, and (2) chemical cues only. In the first experiment, wild-caught parental males were presented with samples of eggs or fry (newly hatched eggs) collected from their own nest or a foreign nest and placed on opposite sides of an aquarium. The time these parental males spent associating with each sample, and their “pecking” behaviours (indicating cannibalism), were recorded. Parental males showed no preference between eggs from their own nest and eggs from a non-neighbouring nest, but they preferred to associate with fry from their own nest over foreign fry. There also was a positive relationship between male body size and the time spent associated with fry from their own nest. Parental males pecked at foreign fry more than 5 times as often as fry from their own nest, though this difference was not statistically significant. In the second experiment, fry that were collected from the nest of a wild-caught parental male or a non-neighbouring nest were placed in different containers and the water from each was dripped into opposite ends of an aquarium. The time the male spent on each side was recorded. In this case, parental males spent more time near the source of water conditioned by unrelated fry, but there was a positive relationship between male condition (fat reserves) and the time he spent near the source of water conditioned by fry from his own nest. Results confirm that chemicals cue nestling recognition by parental male bluegill.

Abstract: Adult male elephants periodically show the phenomenon of musth, a condition associated with increased aggressiveness, restlessness, significant weight reduction and markedly elevated androgen levels. It has been suggested that musth-related behaviours are costly and that therefore musth may represent a form of physiological stress. In order to provide data on this largely unanswered question, the first aim of this study was to evaluate different assays for non-invasive assessment of adrenocortical function in the male African elephant by (i) characterizing the metabolism and excretion of [3H]cortisol (3H-C) and [14C]testosterone (14C-T) and (ii) using this information to evaluate the specificity of four antibodies for determination of excreted cortisol metabolites, particularly with respect to possible cross-reactions with androgen metabolites, and to assess their biological validity using an ACTH challenge test. Based on the methodology established, the second objective was to provide data on fecal cortisol metabolite concentrations in bulls during the musth and non-musth condition. 3H-C (1 mCi) and 14C-T (100 microCi) were injected simultaneously into a 16 year old male and all urine and feces collected for 30 and 86 h, respectively. The majority (82%) of cortisol metabolites was excreted into the urine, whereas testosterone metabolites were mainly (57%) excreted into the feces. Almost all radioactive metabolites recovered from urine were conjugated (86% 3H-C and 97% 14C-T). In contrast, 86% and >99% of the 3H-C and 14C-T metabolites recovered from feces consisted of unconjugated forms. HPLC separations indicated the presence of various metabolites of cortisol in both urine and feces, with cortisol being abundant in hydrolysed urine, but virtually absent in feces. Although all antibodies measured substantial amounts of immunoreactivity after HPLC separation of peak radioactive samples and detected an increase in glucocorticoid output following the ACTH challenge, only two (in feces against 3alpha,11-oxo-cortisol metabolites, measured by an 11-oxo-etiocholanolone-EIA and in urine against cortisol, measured by a cortisol-EIA) did not show substantial cross-reactivity with excreted 14C-T metabolites and could provide an acceptable degree of specificity for reliable assessment of glucocorticoid output from urine and feces. Based on these findings, concentrations of immunoreactive 3alpha,11-oxo-cortisol metabolites were determined in weekly fecal samples collected from four adult bulls over periods of 11-20 months to examine whether musth is associated with increased adrenal activity. Results showed that in each male levels of these cortisol metabolites were not elevated during periods of musth, suggesting that in the African elephant musth is generally not associated with marked elevations in glucocorticoid output. Given the complex nature of musth and the variety of factors that are likely to influence its manifestation, it is clear, however, that further studies, particularly on free-ranging animals, are needed before a possible relationship between musth and adrenal function can be resolved. This study also clearly illustrates the potential problems associated with cross-reacting metabolites of gonadal steroids in EIAs measuring glucocorticoid metabolites. This has to be taken into account when selecting assays and interpreting results of glucocorticoid metabolite analysis, not only for studies in the elephant but also in other species.

Abstract: Male mammals typically outperform their conspecific females on spatial tasks. A sex difference in cues used to solve the task could underlie this performance difference as spatial ability is reliant on appropriate cue use. Although comparative studies of memory in food-storing and non-storing birds have examined species differences in cue preference, few studies have investigated differences in cue use within a species. In this study, we used a one-trial associative food-finding task to test for sex differences in cue use in the great tit, Parus major. Birds were trained to locate a food reward hidden in a well covered by a coloured cloth. To determine whether the colour of the cloth or the location of the well was learned during training, the birds were presented with three wells in the test phase: one in the original location, but covered by a cloth of a novel colour, a second in a new location covered with the original cloth and a third in a new location covered by a differently coloured cloth. Both sexes preferentially visited the well in the training location rather than either alternative. As great tits prefer colour cues over spatial cues in one-trial associative conditioning tasks, cue preference appears to be related to the task type rather than being species dependent.

Abstract: REASONS FOR PERFORMING STUDY: Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing. OBJECTIVE: To determine the prevalence of overstrain injury to the SDFT and SL during training and racing among Thoroughbred flat racehorses in Japan in 1999. METHODS: A retrospective study was performed using a sample population of 10,262 Thoroughbred racehorses. The medical information database of Thoroughbred racehorses registered by the Japan Racing Association (JRA) in 1999 was analysed for SDFT and SL overstrain injury diagnosed by a veterinarian employed by JRA during training and racing. Jump racehorses were excluded from this study. RESULTS: The prevalence of forelimb SDFT tendonitis and SL desmitis was 11.1% (1130 cases) and 3.61% (370 cases) of the population, respectively. In the hindlimb, there were 0.06% (6 cases) and 0.14% (14 cases), respectively. Risks of SDF tendonitis in the forelimb in 3-year-olds or older horses were significantly higher than in 2-year-olds. In contrast, the risk of SL desmitis in the forelimb at age 3 and 4 years was 2.23 and 2.11 times higher, respectively, than in 2-year-olds, but this increased to 5.07 times in those age > or = 5 years. Entire males were at greater risk in comparison to females and geldings. CONCLUSIONS: The results suggest that the prevalence of SDF tendonitis and SL desmitis in the forelimb was associated with the horse's age and sex. The prevalence of SL desmitis increased further with age compared with SDF tendonitis, possibly reflecting a more rapid accumulation of degeneration in this structure. POTENTIAL RELEVANCE: The age-related risk demonstrated in this study provides further support that overstrain injuries are associated with accumulated degeneration. These data provide a valuable resource for further research into the aetiology of tendon injury in the racehorse.