Post-weaning growth of endemic Iberian wild rabbit subspecies, Orycto lagus cuniculus algirus, kept in a semi-extensive enclosure : implications for management and conservation

Abstract

Abstract:Little is known about the endemic Iberian wild rabbit subspecies, Oryctolagus cuniculus algirus, despite its importance in Mediterranean ecosystems. An individual's physical condition is of undisputed importance when evaluating the quality of habitats or restocking enclosures to assess the corresponding population status. We analysed post-weaning body weight and growth of 351 individuals of the endemic Oryctolagus cuniculus algirus subspecies under semi-natural conditions in a breeding enclosure in central Portugal. From these data, we described and estimated growth rates for juvenile and adult stages, and 3 sigmoidal growth models were developed. Body weight showed a linear growth of 0.00765 kg/d until 0.6 kg, whereafter it began to decrease steeply until 1 kg (<0.005 kg/d between 0.6 and 0.7 kg, <0.003 kg/d between 0.7 and 0.9 kg, and <0.001 kg/d then on). An age prediction linear growth equation was estimated for individuals up to 0.6 kg. The von Bertalanffy model best described the observed body weight growth. Juvenile body weight growth of Oryctolagus cuniculus algirus is lower than that of the widespread Oryctolagus cuniculus cuniculus. Our data revealed that Oryctolagus cuniculus algirus seems to be smaller, grows less and for less time than Oryctolagus cuniculus cuniculus, according to the literature. Body weight of the studied individuals seems to be more similar to free-living than to cage-bred individuals, according to the literature. These results should provide important indicators to assist managers and conservationists in accessing habitat quality for wild rabbit populations.

Dynamics of Humoral Immunity to Myxoma and Rabbit Hemorrhagic Disease Viruses in Wild European Rabbits Assessed by Longitudinal Semiquantitative Serology

“…Semiquantitative serology showed linear (MYXV) and cubic (RHDV) relationships with body weight, in which a higher NAR was detected in rabbits weighing >1 kg. Body weight was shown to have an almost linear relationship with age up to around 0.8 kg or 4 months ( 41 ). As rabbits weighing >1 kg are considered adults, our results suggest that survival to adulthood is associated with high NARs for both viruses, emphasizing their role in the population dynamics of European rabbits ( 16 , 32 ).…”

“…Sex was assessed by visual inspection of the external genitalia, and weight was measured with scales (1-g precision). Weight correlates well with age up to 0.8 kg or 4 months of age, according to validated growth curves ( 41 ). Rabbits were released where captured immediately after processing.…”

Keeping an eye on the use of eye-lens weight as a universal indicator of age for European wild rabbits

“…Eq. 3 ) described by Southern 53 and revised by Dunnet 54 with Occ in Australia and recently employed by Ferreira and Ferreira 55 with Iberian Oca. This age calculation only works efficiently for juvenile animals because their weight range exhibits a perfectly linear relation with age 55 (which does not occur for adults).…”

“…3 ) described by Southern 53 and revised by Dunnet 54 with Occ in Australia and recently employed by Ferreira and Ferreira 55 with Iberian Oca. This age calculation only works efficiently for juvenile animals because their weight range exhibits a perfectly linear relation with age 55 (which does not occur for adults). For this reason, and to avoid potential biases associated with aging adult rabbits using this method, we only estimated the age of animals under 500 g at their first capture; this is almost half the weight considered for Oca adults 19 where W is the body weight (g), w i is the weight at weaning age (g), r is the body growth rate (g/day), and A is the postnatal age (days).…”

“…For this reason, and to avoid potential biases associated with aging adult rabbits using this method, we only estimated the age of animals under 500 g at their first capture; this is almost half the weight considered for Oca adults 19 where W is the body weight (g), w i is the weight at weaning age (g), r is the body growth rate (g/day), and A is the postnatal age (days). Postnatal age has been described as 21 days for both subspecies 55 . We used as body growth rate the same recommended by Dunnet 54 (i.e.…”