Comparative study of trophic behaviour and herd structure in wild and feral goats living in a Mediterranean island: Management implications

Abstract

a b s t r a c tThe aim of this study was to compare the trophic behaviour and the social structure of Majorcan wild goats and feral goats present in the island of Majorca. The former are descendants of an ancestral goat ecotype introduced in the island in the late Neolithic, whereas feral goats come from domestic forms introduced recently from the Iberian Peninsula. The study was conducted in four localities of the Serra de Tramuntana, a mountain range located in the northwest of the island of Majorca. Behavioural data were collected in three seasons, summer, winter and spring of 2011-2013, and when goat activity is at its peak, i.e., 3 h after dawn and before dusk. The following variables were recorded: group composition (males, females, and kids) and activity (feeding, walking, resting, and watching). The proportion of time spent on each activity and their frequency were obtained from focal samples. Multivariate analyses of variance (MANOVA) were used to simultaneously analyse the activity variables. A total of 155 observations of 85 herds were registered throughout the study. A similar behaviour pattern has been observed in this study for the two goat ecotypes, feral and wild, apart from some seasonal variations in feeding and resting activities. In summer, feral goats showed higher feeding efforts (duration and frequency) than wild goats; this might be related to a lower efficiency obtaining feeding resources by the former, whereas wild goats, that have inhabited the island for millennia, coexisting with vegetation in periods of lower forage abundance and quality, would be more efficient herbivores during restrictive periods. Average herd size for both ecotypes is smaller than that recorded for domestic goat herds, suggesting a relatively low browsing damage compared to the latter. Also, feral goats apparently have a higher gregarious behaviour than wild ones, which might relate to their domestic origin. Currently, the management of goats on the island is based on maintaining the wild ecotype and eradicate the feral one, whose impact on vegetation is supposedly worse. However, our results show a similar trophic behaviour by both ecotypes, so that their impact on vegetation should also be expected to be similar, indicating that this argument has not enough scientific basis.

Non-native Mammals Are the Main Seed Dispersers of the Ancient Mediterranean Palm Chamaerops humilis L. in the Balearic Islands: Rescuers of a Lost Seed Dispersal Service?

“…We must consider, however, that goats not only act as effective seed dispersers, but also as herbivores, browsing frequently on C. humilis (Rivera Sánchez, 2014) and devastating leaves and inflorescences of many other plants (Mayol et al, 2017); and also as pre-dispersal seed predators (Mancilla-Leytón et al, 2011) like other ruminant species (e.g., Giordani, 2008). These ungulates have been reported to cause much damage on a number of plant species (Rivera-Sánchez et al, 2015), many of them threatened (Mayol et al, 2017). On the other hand, endemic plant species in Mallorca seem to have evolved under the selective pressure of herbivore ungulates (Vives and Baraza, 2010;Bover et al, 2016), and moderate browsing by goats indeed helps to maintain plant communities (Johnson, 2009;Rosa García et al, 2012).…”

Sex-driven neighborhood effects on herbivory in the dioecious Mediterranean palm Chamaerops humilis L.

“…In Mallorca, although the introduction of domestic goats dates back thousands of years (Bover and Alcover 2008 ), the rural abandonment in the 1960s led to the feralization and the expansion of their populations all over the island (more than 20,000 individuals; Vives and Baraza 2010 ; Roque 2017 ). Their impacts on native flora have been well documented in several studies (Cursach et al 2013 ; Capó et al 2021 ; Muñoz-Gallego et al 2022 ) as well as their feeding behavior (Rivera-Sánchez et al 2015 ). Specifically, leaves and inflorescences of C. humilis are intensely consumed by goats, leading to negative effects on pollination and fruit set (Muñoz-Gallego et al 2022 ).…”