Ovarian cycle, reproductive performance and breeding seasonality of Amazonian yellow-footed tortoises (Chelonoidis denticulatus) in the wild

Studies of the reproductive functional morphology of chelonians are important to understand the reproductive phy-
siology, anatomy, and endocrinology of these species. However, data on the reproduction of this group have been
difficult to obtain because of their cryptic habits and as a result the consequent inefficiency of conventional field
methods in detecting individuals in the wild. In this study, we obtained reproductive organs from 347 adult female
yellow-footed tortoises (Chelonoidis denticulatus), one of the most hunted and traded land vertebrates in South
America, donated by local sellers in a wild meat market in the Peruvian Amazon. We described the species’ re-
productive cycle and the influence of climatic factors on reproductive performance. Of the sampled females, 116
(33.4%) were gravid and 231 (66.6%) were non-gravid, including 215 vitellogenic (62.0%) and 16 non-vitellogenic
(4.6%). The mean number of ovarian follicles per female declined from 28.5 (< 10 mm diameter), to 7.1 follicles
(20–40 mm) to 3.2 follicles > 40 mm. Gravid females had in average 3.7 shelled eggs in the oviduct, with a mean egg
diameter of 53.7 mm. The estimated annual reproductive potential in gravid females was 5.1 eggs per clutch, ranging
from one to 22 eggs. There was a strong positive relationship between the diameter of shelled eggs and the straight
carapace length of gravid females. The final phase of the folicular growth, the most demanding energetic process in
chelonian reproduction, correlated with annual rainfall peak, while oviposition was estimated to occur in the dry
season. The yellow-footed tortoise should be considered an opportunistic seasonal breeder, though capable of re-
producing throughout the year. Reproductive yields are linked to climatic events that influence food availability in the
environment. To improve the sustainable use of this species, adult females should be harvested primarily during
reproductive quiescence, from the end of the laying period in the late dry season to the mid-rainy season when large
follicles appear, to avoid taking gravid females. Our results are useful not just to better understand the reproductive
biology of terrestrial chelonians but can inform the conservation management of harvested species.