Age, fertility and reproductive behavior in cuban crocodiles,Crocodylus rhombifer, at the smithsonian's national zoological park

Abstract

The Smithsonian's National Zoological Park (NZP) has a long history with Cuban crocodiles, Crocodylus rhombifer, beginning in 1900's when the first animals arrived at the NZP. Today, the Zoo has two breeding groups of C. rhombifer and has observed and analyzed reproductive behavior and fertility rates over the last three years. Fertility rates were determined initially by observing the formation of an opaque band that forms on the shell of a fertile egg, called banding. The fertility rates by banding were later compared to the observation made after opening the eggs to verify fertility. In addition to tracking fertility, nesting and agonistic behavior were also observed. Several notable observations were documented over the same period. These included a male predating a nesting female's eggs, increased aggression between two females housed together, the continued development of a partially banded egg, and the discovery of 19 additional egg shells post oviposition by both females in the enclosure. Here we discuss the nest phenology, fertility and behavior of the five exhibited C. rhombifer at the Smithsonian's National Zoological Park over a 3-year period. Zoo Biol. 34:278-284, 2015. © 2015 Wiley Periodicals Inc.

Crocodilian perivitelline membrane‐bound sperm detection

“…Historically there has been an implied relationship between banding rates and fertility (Augustine & Watkins, ; Deitz & Hines, ; Tryon, ; Webb, Buckworth, Sack, & Manolis, , Webb, Manolis, Buckworth, & Sack, ). As crocodilian eggs begin to develop within the female pre‐oviposition, EEM could occur before the development of the band (Ferguson, ).…”

“…Despite the presence of sperm in every egg, there were differences in developmental rates. Differences in developmental rates may be a result of social grouping as crocodilians are behaviorally complex (Augustine, Pryes, & Evans, ; Augustine & Watkins, ; Brien, Lang, Webb, Stevenson, & Christian, ; Brien, Webb, Lang, McGuinness, & Christian, , ; Garrick & Lang, ; Garrick, Lang, & Herzog, ; Lang, ; Thorbjarnarson & Hernández, ; Vliet , , ). In captive crocodilian groups, competition for resources leads to the establishment of dominance hierarchies instead of established territories (Brien et al, ) and increased competition leads to agonistic behaviors (Drummond, ; Lovern & Jenssen, ).…”

“…Three reproductive female C. rhombifer are housed on exhibit at the Smithsonian's National Zoological Park (NZP). All three females (F1, F2, and F3) seasonally breed and lay eggs (Augustine & Watkins, ). Five animals are housed in two breeding cohorts, a pair (M1 and F1) and a trio (M2, F2, and F3) in adjacent enclosures.…”

Impacts of the season and reproductive status on fecal reproductive and adrenocortical steroid metabolites in zoo Cuban crocodiles (Crocodylus rhombifer)

“…Cuban crocodile populations (Augustine, Pryes, & Evans, 2017;R. Ramos-Targarona et al, 1996) were used to group data into seasons (breeding, nesting, and off season).…”

“…This study demonstrated the utility of measuring excreted steroid metabolites in the C. rhombifer at NZP and found similar seasonal patterns in reproductive hormones to those documented in the blood plasma of other crocodilians (Lance, 1994). Typically, males are behaviorally more aggressive during the breeding season (October-March), defending their territories along the fence line of the habitats (Augustine et al, 2017). Therefore, we expected to see elevated FGM and FAM concentrations in males during the breeding season, as testosterone concentrations are positively correlated with baseline corticosterone (Eikenaar, Husak, Escallon, & Moore, 2012).…”