Abstract: This review covers selected literature from 1982 to the present on some of the ecological, behavioral, and biochemical aspects of hydrocarbon use by insects and other arthropods. Major ecological and behavioral topics are species- and gender-recognition, nestmate recognition, task-specific cues, dominance and fertility cues, chemical mimicry, and primer pheromones. Major biochemical topics include chain length regulation, mechanism of hydrocarbon formation, timing of hydrocarbon synthesis and transport, and biosynthesis of volatile hydrocarbon pheromones of Lepidoptera and Coleoptera. In addition, a section is devoted to future research needs in this rapidly growing area of science.

Abstract: Faecal steroid hormone metabolites are becoming increasingly popular as parameters for reproductive functions and stress. The extraction of the steroids from the faecal matrix represents the initial step before quantification can be performed. The steroid metabolites present in the faecal matrix are of varying polarity and composition, so selection of a proper extraction procedure is essential. There have been some studies to address this complex but often neglected point. Radiolabelled steroids (e.g. cortisol or progesterone) have frequently been added to faecal samples to estimate the efficiency of the extraction procedures used. However, native, unmetabolized steroids are normally not present in the faeces and therefore the results are artifi- cial and do not accurately reflect the actual recoveries of the substances of interest. In this respect, recovery experiments based on faecal samples from radiometabolism studies are more informative. In these samples, the metabolite content accurately reflects the mixture of metabolites present in the given species. As a result, it is possible to evaluate different extraction methods for use with faecal samples. We present studies on sheep, horses, pigs, hares and dogs that utilized samples containing naturally metabolized, 14C-labelled steroids. We recommend extracting faecal steroids by simply suspending the faeces in a high percentage of a primary alcohol (for glucocorticoid metabolites 80% aqueous methanol proved best suited for virtually all mammalian species tested so far). Not only does the procedure significantly increase the total amount of recovered radioactivity, it also increases the percentage of unconjugated metabolites, which are more likely to be recognized by the antibodies used in various immunoassays. The advantages of this extraction procedure are clear: it is very easy to use (no evaporation step is needed), it yields high recoveries and variation based on the extraction procedure is reduced to a minimum.

Abstract: In this study, we investigated endocrine factors and behaviour in free-living Common hamsters (Cricetus cricetus) during reproductive and non-reproductive periods of the annual cycle. We applied a non-invasive method to gain information on seasonal changes in adrenocortical activity in male and female hamsters by analysing faecal glucocorticoid metabolite concentrations (FCM). In addition, plasma progesterone concentrations were monitored in females throughout the non-hibernation season. The animals were live-trapped from spring emergence until the onset of hibernation in autumn. Reproductive status was determined at capture and blood and faecal samples were collected. During behavioural observations, agonistic and sexual interactions were recorded. FCM concentrations were significantly higher in males than in females during the reproductive period. In males, a pronounced increase in FCM during the reproductive period coincided with high frequencies of intrasexual aggression. In females, FCM levels remained relatively constant. Aggressive behaviour in females increased during the reproductive period, but was much less frequent than in males. Females, which successfully raised a second litter after a postpartum oestrus and concurrent lactation and gestation had lower FCM levels than individuals, which lost their second litter after parturition. As expected, plasma progesterone concentrations were low before and after the reproductive period. During gestation, levels peaked and remained elevated during lactation. The results of this field study provide insight in critical periods associated with reproduction in male and female Common hamsters.

Abstract: This experiment investigated the effects of positive and negative tactile handling on the stress physiology and behaviour of dairy heifers. Forty-eight 5-14-month-old nonlactating Holstein-Friesian heifers were allocated to one of two handling treatments, either positive or negative tactile handling, over four time replicates. Handling was imposed twice daily, 2-5 min per session and involved moving animals individually along a 64 m outdoor route. The negatively handled heifers took longer to approach within 1 and 2 m of a stimulus person in a standard test, than their positively handled counterparts (P<0.001) and had a greater flight distance to an approaching stimulus (P<0.001). The time taken by the heifers to approach within 1 and 2 m of a familiar person was similar to that taken to approach within 1 and 2 m of an unfamiliar person in the standard test (P<0.05). There was a tendency for heifers to have a greater flight distance from the approaching unfamiliar person than from the approaching familiar person (P=0.06). The negatively handled heifers had greater (P<0.05) increases in total cortisol concentrations 5, 10 and 15 min after exposure to a human and had higher (P<0.05) free cortisol concentrations in the afternoon than the positively handled heifers. It is concluded that the nature of the human contact affects the subsequent behavioural response of heifers to humans. This behavioural response may extend to other humans through the process of stimulus generalisation, although there was some evidence of moderate discrimination. Negative handling results in an acute stress response in the presence of humans and also leads to a chronic stress response. Further research into the effect of these stress responses on milk production and welfare in fearful cows in a commercial situation is suggested.

Abstract: Background Recent record rainfall in much of semi-arid Central Australia is the most likely reason for a feral horse population increase in excess of normal. Uncontrolled numbers of feral horses have habitat degradation and animal welfare implications. Objectives The aims of this study were to investigate the social structure of feral horses and assess their population growth rate following unseasonably high rainfall. Methods The study area was 4000 km2 of unmanaged, semi-arid country in Central Australia (latitude 24.50°S, longitude 132.10°E). Horses were identified by descriptive features from ground searches, movement-activated cameras and ‘hides’ positioned at key water holes. Wherever possible, sex and age categories were documented. Population growth rate was estimated by the number of foals divided by the number of horses older than 1 year in the observed population. Results A total of 1424 horses were identified and categorised, of which 335 were foals born within the current year. Only 123 juveniles were identified. Of the adult horses, 53.4% were male and 46.6% were female and this differed from parity (P = 0.04). Of the mares, 71.9% had a foal at foot and the population growth rate was 29.5%. Conclusions With a sustained population growth rate of 29.5%, this population of feral horses will more than double within 3 years. The high population increase will likely have a detrimental effect on native fauna and flora and the fragile, semi-arid ecosystems of Central Australia. After a period of high rainfall and plentiful resources, ‘normal’ drought conditions will return and many feral horses will starve and die as they compete for limited resources.