REPRODUCTIVE ECOLOGY OF THE HORSESHOE WHIP SNAKE (COLUBER HIPPOCREPIS) IN THE IBERIAN PENINSULA

-Data on the reproductive ecology of the Horseshoe whip snake (Coluber hippocrepis) are scarce and largely anecdotal in northern Mediterranean populations of this species. Dissections of preserved specimens from the southeast of the Iberian Peninsula, together with field observations, provided information on size at sexual maturity, reproductive and fat body cycling, clutch size, hatching period, and feeding frequency. Males attain sexual maturity at about 500 mm snout-vent length (SVL) and females at 680 mm SVL. As with populations from Northern Africa, males exhibit a prenuptial spermatogenic cycle. The complete reproductive cycle (spermatogenesis, vitellogenesis, mating, shelling, oviposition, incubation, and hatching) occurs within the same calendar year. The northern limit of this spermatogenic cycle also coincides with the northern limit of the distribution of the species. The female reproductive cycle is seasonal, and most sexually mature females reproduce annually. Vitellogenesis is associated with a decline in the fat body level. Oviposition occurs in late June to early July, the mean clutch size is 6.8 eggs, and there is a significant correlation between female size and fecundity. Females feed rarely when gravid. The hatching period begins in late August and lasts to mid-September. Offspring size was 237 to 308 mm SVL, and offspring mass 6.1 to 9.0 g. The reproductive biology of snakes is less well understood than that of any other reptilian group except the crocodilians (Seigel and Ford, 1987). In the Western Palearctic region, most of the studies on reproductive biology of snakes have focused on viperids (Volsoe, 1944; Nilson, 1981; Saint Girons and Duguy, 1992) or colubrids from northern and central Europe (Bourliere and Petter-Rouseaux, 1955; Goodar and Spellerberg, 1980; Naulleau, 1992; Luiselli et al., 1996, 1997), and there are few studies on species inhabiting Mediterranean habitats (but see e reproductive biol gy of snakes is less ll understo d than that of any other r ptilian up except the croc dilians (Seig l and Ford, 7). In the Western Pale rcti region, most of studies on reproductive biology of snakes e focused on viperids (Vols e, 1944; Nilson, 1; Saint Girons and Dug y, 1992) or c lui s from northern and central Europe (BourCheylan et al., 1981; Hailey and Davies, 1987; Agrimi and Luiselli, 1994). Coluber hippocrepis is a long and slender-bodied colubrid, with a total length of up to 1800 mm, and no sexual dimorphism in body size (Feriche et al., 1993). It is found in a variety of warm Mediterranean habitats throughout northern Tunisia and Algeria, most regions of Morocco, and the eastern and southern half of the Iberian Peninsula. The populations inhabiting the Iberian Peninsula have been isolated from the original populations in North Africa since la et al., 1981; Hailey and Davies, 1987; i i and Luiselli, 1 94). hippocrepis is a long and slender-bodl brid, with a tota length of up to 1800 a d no sexual dimorphism in body size i e et al., 1 93). It is found in a variety of editerranean habitats throughout northisia and Algeria, most regions of Mo, a d the eastern and southern half of the i Peninsula. The populations inhabiting 202 This content downloaded from 207.46.13.83 on Sun, 23 Oct 2016 05:04:44 UTC All use subject to http://about.jstor. org/terms REPRODUCTIVE ECOLOGY OF COLUBER HIPPOCREPIS the formation of the Strait of Gibraltar, approximately 5.3 x 106 yr (Busack, 1986; B. Sanchiz, pers. cor.). Although the distribution of the species in southern Europe suggests that males should retain the spermatogenic prenuptial cycle exhibited by the specimens from Morocco (Bons, 1967; Pozuelo, 1974; Saint Girons, 1982), the reproductive biology of the populations from the northern Mediterranean Basin has not