Breeding success and juvenile survival in a reintroduced captive-bred population of Asian houbara bustards in the United Arab Emirates

Abstract

Identifying factors influencing breeding success in endangered species is vital for undertaking appropriate conservation measures. The reintroduced population of the captive-bred Asian houbara bustard Chlamydotis macqueenii in reserves of the western United Arab Emirates (UAE) has been closely monitored since releases first began in 2005. Based on 8 yr of monitoring data, we provide novel information on female breeding probability and breeding success within a desert ecosystem. Additionally, we explore factors influencing some breeding parameters. Female breeding probability was on average 0.14 ± 0.31 SD (0.01 ± 0.03 for females less than 1 yr old and 0.23 ± 0.38 for females older than 1 yr). Nest initiation date was influenced by temperature and time. Rainfall during a breeding season increased its length. The estimated nest survival rate for 23 d was 0.52, and was negatively influenced by nest initiation date. Chick survival rate to the age of 6 wk was 0.50 ± 0.39 SD, and survival rate of juveniles in their first year was 0.64 ± 0.02 SE. Our results highlight the ability of captive-bred released houbara in the UAE to breed and of wild born juveniles to survive, 2 vital prerequisites for a successful reintroduction programme. Furthermore, these breeding parameters are similar to the very few that have been reported in other studies of wild resident houbara populations. However, population recruitment rate was low (0.04 individuals per female), resulting mainly from low female breeding probability under harsh weather conditions.

Timing of Release Influence Breeding Success of Translocated Captive-Bred Migrant Asian Houbara Bustard

“…Age had positive effects on breeding parameters, resulting in older females nesting earlier, having a higher breeding probability, laying larger eggs, and having a higher re-clutching probability. These findings are consistent with previous results on resident Asian houbara in UAE (Azar et al, 2018), African houbara in Morocco (Bacon et al, 2017), and supporting the compelling evidence of age effect on breeding parameters (Christians, 2002;Williams, 2012).…”

“…In the houbara, the laying time in the season is a major factor in the regulation of breeding success, affecting females' investment in terms of clutch size, egg volume and re-clutching probability (Bacon et al, 2017;Azar et al, 2018). This is usually explained in relation to underlying physiological mechanisms determining female breeding investment such as reduction in food availability or increase in predation intensity (Decker et al, 2012).…”

“…Eight parameters were evaluated: (1) breeding probability, estimated from tracked females monitored for a minimum of 60 days on breeding range, (2) nest initiation date, measured for all nesting attempts, as day of year (DOY), estimated from the mean incubation stages of all eggs in the clutch (Combreau et al, 2002) or by subtracting the species average incubation period (23 days) from the observed hatching date, (3) egg volume, calculated following Hoyt (1979), ( 4) clutch size, given as the maximum number of eggs observed in a nest, (5) daily nest survival (DNS), the daily probability of a nest to survive, (6) hatching rate, the proportion of hatched eggs to clutch size, (7) female re-clutching probability following nest failure, estimated from tracked females, (8) chick survival, estimated from tracked females seen with chicks after hatching. Productivity (number of chicks per female on breeding range), was the product of breeding probability, clutch size, nest survival, hatching rate, and chick survival (Azar et al, 2018).…”

“…Juveniles released in autumn can nest following their first full migration when they are around 1 year old, whereas juveniles released in spring can nest shortly after their release on the breeding ground and prior to their first migration, resulting in different life histories and experiences prior to key events (breeding and migration). Assessing reproductive success requires evaluation of all composite traits involved, beginning with the female decision to breed through egg laying and incubation, and ending with chick survival traits, all of which influence productivity (Azar et al, 2018). Here, we provide the first estimates of breeding traits of captive-bred migrant houbara using a large-scale data set from 519 houbara nests monitored between 2013 and 2018 in Uzbekistan and central Kazakhstan (two regions in the core breeding range of migrant Asian houbara), and we investigate (1) the effects of female origin (wild vs. captive-bred), (2) timing of release (autumn vs. spring), and (3) age on eight breeding parameters.…”

The potential distribution of wintering and breeding populations of Asian HoubaraChlamydotis macqueeniiin Iran

“…However, we observed a decreasing trend in occurrence of the breeding populations with increasing temperature, whereas this trend was opposite for the wintering populations. The probability of chick survival may decrease in areas with relatively higher temperatures (Koshkin et al 2016, Azar et al 2018) such as the hot and dry deserts of the south and central Iran. Wintering houbaras select habitats with mild winters as such areas provide more food.…”