Determination of seasonality in southern hairy-nosed wombats (Lasiorhinus latifrons) by analysis of fecal androgens

Little is known about the reproductive biology of Australia's critically en dangered northern hairy-nosed wombat (Lasiorhinus krefftii), largely due to its cryptic nature and the difficulty in accessing the small remaining pop ulation of about 70 animals. Using the noninvasive technique of fecal stero id analysis, we have examined the endocrinology of the more common yet clos ely related southern hairy-nosed wombat (Lasiorhinus latifrons). The aims o f this study were to 1) develop and validate fecal androgen analysis in thi s species, 2) examine and compare seasonal differences in fecal and plasma androgens in male wombats, and 3) correlate seasonal differences in androge ns with changes in male accessory glands (prostate and bulbourethral gland) . Fecal androgens were extracted in ether; concentrated; separated by HPLC into testosterone (T), dihydrotestosterone (DHT), and 5 alpha-androstane-3 alpha,17 beta-diol (Adiol) fractions; and quantitated by RIA. The concentra tions of androgens in fecal pellets from 14 wild southern hairy-nosed womba ts as determined by RIA varied over the range 6.6-25.0 ng/g dry weight for T, 4.0-24.2 ng/g dry weight for DHT, and 0-34.8 ng/g dry weight for Adiol. For each androgen, a highly significant linear correlation was observed bet ween plasma and fecal concentrations. When individuals were grouped into ei ther breeding season (pellets collected between August-November) or nonbree ding season (collected between February-April), significant (P < 0.05) diff erences between seasons were observed for both plasma and fecal T, plasma D HT, and fecal Adiol. For all androgens, the mean fecal and plasma concentra tions were higher during the breeding season than the nonbreeding season. A significant (P < 0.001) correlation was observed between fecal T and prost ate weight, while DHT and Adiol correlations were nonsignificant. Significa nt correlations were observed, however, between all three fecal androgens a nd bulbourethral gland weight. These studies demonstrate that fecal T is a valid indicator of reproductive status in the mate southern hairy-nosed wom bat, with significant correlations observed between fecal T, plasma T, and prostate and bulbourethral gland weights. These findings have important imp lications for the study of the reproductive endocrinology of the critically endangered northern hairy-nosed wombat.