Jorge Cassinello

Estimation of European wild boar relative abundance and aggregation: a novel method in epidemiological risk assessment

Wild boars are important disease reservoirs. It is well known that abundance estimates are needed in wildlife epidemiology, but the expense and effort required to obtain them is prohibitive. We evaluated a simple method based on the frequency of faecal droppings found on transects (FBII), and developed a spatial aggregation index, based on the runs test statistic. Estimates were compared with hunting data, and with porcine circovirus and Aujeszkys disease virus seroprevalences and Mycobacterium tuberculosis complex and Metastrongylus spp. prevalence. The FBII and the aggregation index were correlated with the hunting index, but both of the former estimates correlated better than the latter with the disease prevalences. Hence, at least in habitats with high wild boar densities, the FBII combined with the aggregation index constitutes a cheap and reliable alternative for wild boar abundance estimation that can be used for epidemiological risk assessment, even outside the hunting season and in areas with no available data on hunting activities.

A comparative study of ejaculate traits in three endangered ungulates with different levels of inbreeding: fluctuating asymmetry as an indicator of reproductive and genetic stress.

We studied three closely related species of endangered gazelles (Gazella dorcas, Gazella dama and Gazella cuvieri) with different levels of inbreeding in order to determine at which intensities inbreeding influences ejaculate traits. We also examined whether fluctuating asymmetry (FA) is a reliable indicator of genetic as well as reproductive stress. Our results show that, within each population, the individual coefficient of inbreeding is inversely related to ejaculate quality only in the species with the highest levels of inbreeding (G. cuvieri). In addition, FA is a reliable indicator of individual levels of inbreeding in both the species with the highest levels of inbreeding (G. cuvieri) and the species with intermediate levels of inbreeding (G. dama). Thus, FA appears in individuals whose levels of inbreeding are still not high enough to affect male reproductive potential and should therefore be considered a sensitive indicator of genetic stress. Finally, FA is also a reliable indicator of male reproductive stress since it is related to individual semen quality in all the species studied.

Adaptive Variation in Litter Size and Sex Ratio at Birth in a Sexually Dimorphic Ungulate

In the Saharan arrui litter size and sex ratio at birth are strongly influenced by parity and maternal dominance rank at the time of conception. When females give birth for the first time they always produce single offspring, while multiparous females produce both singletons and twins. As maternal rank increases females tend to produce the following sequence: F, FF > M > MF > MM. This sequence differs from Williams’s (1979) prediction, in that FF are produced by females of lower rank than M. This may be so, because the Saharan arrui is a strongly sexually dimorphic species in which the differential costs of sons and daughters may be greater than in Williams’s model, and in which dominant females have much to gain from producing exceptionally good males. Single males are born heavier than other types of calve; among twins, investment in male—male twins seems particularly high because they are as heavy as female singletons and heavier than other twins. In addition, investment in males increases with maternal rank, while investment in females seems unaffected. Despite lower levels of investment in females, single females are more likely to survive than single males and twins.

High-ranking females bias their investment in favour of male calves in captive Ammotragus lervia

Abstract Calf suckling behaviour is a valid measure of maternal investment in the Saharan arrui, Ammotragus lervia sahariensis, since this variable is strongly correlated with the inter-birth interval. High-ranking females allocate their resources preferentially towards their sons, as the average suckling rate is significantly higher in male calves than in female calves during their 1st month of life, when maternal investment reaches the highest values of the whole lactation period. However, average suckling-bout duration shows no sex differences. Some maternal behaviours, such as sniffing and licking, are strongly correlated with suckling events. Only during the calves’ 1st week is the mother responsible for maintaining proximity; but from the following week on the calves are mainly responsible for maintaining it. In addition, when the calves are 1 month old, high-ranking females tend to maintain a stronger link with their male calves. Female calves spend more time with their mothers than male calves during their 1st month of life, if the mother’s rank is lower than 60%; otherwise, the opposite occurs, male calves being close to their mothers for longer, even from their 1st week of life. Finally, the higher the maternal rank the higher the proportion of male calves delivered.

The Iberian ibex is under an expansion trend but displaced to suboptimal habitats by the presence of extensive goat livestock in central Spain

In this paper an updated distribution of the Iberian ibex (Capra pyrenaica, Schinz 1838) in the central Spanish region of Castile–La Mancha is shown. The species is present in 19% of the study region, and in areas not cited so far in the literature. A detailed analysis of habitat suitability was also carried out, applying a␣new methodology, Ecological-Niche Factor Analysis, which uses presence data to␣build a habitat suitability map of a given species. As livestock activity is quite intense in the region, the presence of a potential competitor, the domestic goat (Capra hircus), was included in the analyses. Factors affecting ibex relative abundance were determined by means of a nested stepwise multiple regression, where livestock presence/absence was the nested factor. The presence of livestock has a negative effect on ibex relative abundance, causing the ibex to select areas of poor, sparse vegetation, cultivated lands and forests, whereas in the absence of livestock, the ibex is mainly present in pasture–scrub lands and non-cultivated lands. Conservation implications of these results are discussed in the context of a Mediterranean region where extensive livestock grazing systems abound.

Human-Induced Range Expansion of Wild Ungulates Causes Niche Overlap between Previously Allopatric Species: Red Deer and Iberian Ibex in Mountainous Regions of Southern Spain

Game species exploitation usually causes an increase in their distribution, further from their own dispersal potential, but we know too little about the ecological effects that these human-induced expansions may produce. The realized niche of the red deer was analyzed by means of habitat suitability modelling in the present study. Two populations inhabiting different geographic areas have been distinguished according to their origin, one is native to the study area and the other was translocated as a result of human hunting interests. Translocated red deer showed strong distributional overlap with the native Iberian ibex. However, a comparative analysis of the potential distribution of native red deer and Iberian ibex populations did not yield a significant niche overlap. Thus, we conclude that the observed niche overlap between the Iberian ibex and the red deer in the study area would not have taken place without human intervention. We discuss these results in the light of biological invasions and native species translocation programmes, and conclude that human-induced range expansion of native species should be regarded as a specific case of invasive species.

Multi‐male captive groups of endangered dama gazelle: Social rank, aggression, and enclosure effects

A study carried out in four multi-male groups of captive dama gazelle (Gazella dama mhorr) characterized the social rank order of males and possible enclosure effects on aggression rate. A strong relationship between rank and age was found. The results also showed that dominant individuals in the two smallest enclosures were more aggressive than their herdmates, suggesting a more stressful environment, which might precipitate unstable or challenged hierarchies when the animals live in a more restricted enclosure. Subordinate males performed submissive responses at a higher frequency, irrespective of the size of the enclosure. The frequency of interactions between the gazelles, on the other hand, was affected by enclosure size, since high-ranking males showed higher values than low-ranking males in the two smallest enclosures. Frequencies of aggressive acts, retreats, and related interactions were similar in all the herds. Implications for the management of the species in captivity are discussed. Zoo Biol 19:121–129, 2000.

Ammotragus free-ranging population in the south-east of Spain: a necessary first account

This is the first attempt to investigate some characteristics of a Spanish population of Ammotragus lervia introduced in the wild back in 1970. Apart from a short account of the population history and proceeding up to the present, a comparison between population data reported for the American wild populations and the Spanish one is provided. The surveys were conducted during breeding and rutting seasons. The majority of the herds sighted in Sierra Espuña were made up of 1–10 individuals, and adult males were more frequently observed during rutting. The group composition more commonly observed during breeding is that of adult females and subadults, i.e., nursery herds. A different habitat use was obtained depending on the season and sex-age class. These results are consistent with the dynamics of ungulates and their reproductive phenology. Suggestions for future research and conservation-management concerns in the area are provided.

Seasonality and edge effect determine herbivory risk according to different plant association models.

We report evidence of hierarchical resource selection by large herbivores and plant neighbouring effects in a Mediterranean ecosystem. Plant palatability was assessed according to herbivore foraging decisions. We hypothesize that under natural conditions large herbivores follow a hierarchical foraging pattern, starting at the landscape scale, and then selecting patches and individual plants. A between- and within-patch selection study was carried out in an area formed by scrubland and pasture patches, connected by habitat edges. With regard to between-patch selection, quality-dependent resource selection is reported: herbivores mainly consume pasture in spring and woody plants in winter. Within-patch selection was also observed in scrub habitats, influenced by season, relative patch palatability and edge effect. We defined a Proximity Index (PI) between palatable and unpalatable plants, which allowed verification of neighbouring effects. In spring, when the preferred food resource (i.e. herbs) is abundant, we observed that in habitat edges large herbivores basically select the relatively scarce palatable shrubs, whereas inside scrubland, unpalatable shrub consumption was related to increasing PI. In winter, a very different picture was observed; there was low consumption of palatable species surrounded by unpalatable species in habitat edges, where the latter were more abundant. These outcomes could be explained though different plant associations described in the literature. We conclude that optimal foraging theory provides a conceptual framework behind the observed interactions between plants and large herbivores in Mediterranean ecosystems.

Characterization of the estrous cycle and reproductive traits of the aoudad (Ammotragus lervia) in captivity.

In this study the estrous cycle of the aoudad has been analyzed and characterized for the first time, using non-invasive methods for tracking reproductive cyclicity. The duration of the estrous cycle is 23 days (range 16-32 days), with a luteal phase of 17 days (range 12-27 days) and an interluteal phase of 6 days (range 3-14 days). The estrous cycle did not differ between females, but it was affected by the time of the year. Intraindividual variation of the cycle was observed in one out of the nine individuals. The average hormone concentration values, the estrogen:progestogen ratio, as well as their minimum and maximum values for each interluteal and luteal phases of the estrous cycle, are shown. Interindividual differences found in these values were basically associated with age. Females tended to start their cycle when in the presence of an adult male. Anestrus was observed in study females except for the oldest (14 years old). Age and anestrus onset were correlated, with younger females starting earlier than the older ones. This study reveals that Ammotragus reproductive biology is more similar to that of Capra than Ovis, except for some endocrinological features.