Archive eggs: A research and management tool for avian conservation breeding

Abstract

Worldwide, approximately 168 bird species are captive‐bred for reintroduction into the wild. Programs tend to be initiated for species with a high level of endangerment. Depressed hatching success can be a problem for such programs and has been linked to artificial incubation. The need for artificial incubation is driven by the practice of multiclutching to increase egg production or by uncertainty over the incubation abilities of captive birds. There has been little attempt to determine how artificial incubation differs from bird‐contact incubation. We describe a novel archive (data‐logger) egg and use it to compare temperature, humidity, and egg‐turning in 5 whooping crane (Grus americana) nests, 4 sandhill crane (G. canadensis) nests, and 3 models of artificial incubator; each of which are used to incubate eggs in whooping crane captive‐breeding programs. Mean incubation temperature was 31.7° C for whooping cranes and 32.83° C for sandhill cranes. This is well below that of the artificial incubators (which were set based on a protocol of 37.6° C). Humidity in crane nests varied considerably, but median humidity in all 3 artificial incubators was substantially different from that in the crane nests. Two artificial incubators failed to turn the eggs in a way that mimicked crane egg‐turning. Archive eggs are an effective tool for guiding the management of avian conservation breeding programs, and can be custom‐made for other species. They also have potential to be applied to research on wild populations. © 2012 The Wildlife Society.

Trading off hatching success and cost in the captive breeding of Whooping Cranes

“…We have now demonstrated an association between high daily temperatures and decreased daily egg turning during incubation and low hatch success. Therefore, in addition to Smith et al's (2012) recommendations for Whooping Crane artificial incubation protocols to include a dry-bulb temperature of 33-34°C and machine turning of the eggs, to maximize hatching success our results indicate that that daily mean temperatures remain below 33.64°C (the temperature at which 70% of eggs successfully hatch).…”

“…An open, and important, question is how the incubation environment affects fitness of hatchlings, as this may have consequences for the success of conservation translocation programmes. Smith et al (2012) suggested that a more successful artificial incubator would incubate at a lower temperature, would have greater variance in temperature, and have a rate of egg turning that allowed for a more even representation of egg positions relative to current models. We have now demonstrated an association between high daily temperatures and decreased daily egg turning during incubation and low hatch success.…”

“…To confirm that the variance and mean of temperature, humidity and egg turning rate were significantly higher and less variable during artificial incubation than natural incubation (Smith et al . 2012), we predicted that low variability in temperature and humidity, high temperature and humidity, and a low number of egg turns would be characteristic of artificial incubation compared to natural incubation. Finally, to inform captive breeding management, we developed a stochastic simulation to predict the expected number of hatched eggs when using Whooping Crane incubation, Sandhill Crane incubation and an artificial incubator, and discuss trade‐offs between cost and breeding output in the selection of captive breeding practises.…”

“…2011; Smith et al . 2012). We therefore hypothesized that low variability in temperature and humidity, high mean temperature and humidity, and a low number of egg turns would lead to greater hatching failure of Sandhill/Whooping Crane eggs.…”

“…In a further study, Smith et al . (2012) found that the variance and mean of temperature, humidity and egg turning rate were significantly higher and less variable during artificial incubation than crane incubation. Notably, changes in these environmental parameters are known to influence hatching outcomes in other avian species (Gabel and Mahan 1996; Deeming 2002b; Deeming 2002c; Hepp and Kennamer 2012; DuRant et al .…”