Do headstart programs work? Survival and body condition in headstarted Mona Island iguanas Cyclura cornuta stejnegeri

Abstract

Headstarting refers to the raising of hatchlings in captivity and subsequently releasing them into the wild and it is a widely used tool to protect endangered species by increasing survivorship. Evaluating the success of headstart programs is necessary but challenging. We evaluated a headstart program for the endangered Mona Island iguana Cyclura cornuta stejnegeri by analyzing demographic and spatial data and by comparing growth rate, body condition, and external parasitic load of headstarted and wild iguanas. Hatchlings were released at about 3 yr age. Minimum survival rate was 40.3 %, at 7.6 to 48.3 mo after release. Most migrated from the release site back to the rearing facilities about 633 m away. Density around the rearing facility increased from 7.5 to 11.5 iguanas ha-1 (25 of 75 captures were headstarted iguanas). Released headstarted iguanas exhibited growth rates similar to the maxima observed in captive and wild mid-sized iguanas. Growth rates decreased immediately prior to release, indicating that husbandry practices ought to be reviewed. There was no evidence for an effect of captivity on susceptibility to external parasites. Increased local density indicates that the program was successful. However, the longer-term success remains unknown, as most headstarted iguanas returned to the headstart facility without establishing territories typical for adult wild Mona iguanas.

Temperature-Dependent Sex Determination and Contemporary Climate Change

“…For example, release of headstarted Mona Island iguana ( Cyclura cornuta stejnegeri -a species with GSD) at 3 years of age has resulted in an increase in the density of adults on Mona Island relative to islands where headstarting programs were not in effect [Pérez-Buitrago et al, 2008]. Elasticity analysis generally supports the principle that increasing the survivorship of juvenile age classes will enhance the growth rates of reptile populations [e.g.…”

Survivorship and Spatial Patterns of an Urban Population of Texas Horned Lizards

“…Headstart programs, in which individuals of a threatened or endangered species are hatched or raised in captivity (Burke 2015), are used as a management strategy for a variety of lizard species (Pérez‐Buitrago et al 2008, Santos et al 2009). Texas horned lizard headstart and captive breeding programs are now common practice in several Texas zoos, with hatchlings released just prior to brumation (i.e., period of below ground inactivity or torpor during the winter season), and no active monitoring after release (Cuthbert 2018, Scudder 2018).…”

Assessing conservation tools for an at-risk shorebird: Feasibility of headstarting for American OystercatchersHaematopus palliatus

“…One tool that has received considerable attention for the management of declining or threatened avian populations is headstarting, or the artificial incubation of eggs and subsequent placement of newly hatched chicks in original or foster nests. Also referred to as ‘hatch-and-switch’, headstarting has been used in various forms for cranes, shorebirds, passerines and other endangered birds (Powell et al 1997, Robertson et al 2005, King et al 2013, Lobo and Marini 2013) and has also been employed for the conservation of iguanas (Perez-Buitrago et al 2008, Escobar et al 2010). Headstarting appears to be most effective as a tool to avoid likely nest failures when productivity is lost during incubation and when parents can be enticed to remain at nests through the placement of artificial eggs (Elliott et al 2001).…”