Wild-reared aplomado falcons survive and recruit at higher rates than hacked falcons in a common environment

Brown, Jessi L.; Collopy, Michael W.; Gott, Erin J.; Juergens, Paul; Montoya, Angel B.; Hunt, W. Grainger

doi:10.1016/j.biocon.2006.02.021

Cited by 47 publications

(45 citation statements)

References 28 publications

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“…In any case, our results provide no support for a simple behavioural origin of the difference in body condition, as neither activity patterns nor diet differed between released and wild birds. Whatever determined body condition in surviving released birds studied, the poor condition apparently translated into low survival rates: Just like in many other studies of captive-reared animals (Brown et al 2006;Le Gouar et al 2008;Parish and Sotherton 2007), we found that survival in Mallards was extremely low after release into the wild. Models fitting best with our data suggest that survival of released Mallards during their first year in the wild was less than 0.04.…”

Section: Discussionmentioning

confidence: 68%

Low survival after release into the wild: assessing “the burden of captivity” on Mallard physiology and behaviour

Guillemain

Elmberg

et al. 2011

Eur J Wildl Res

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Captive-reared animals used in reinforcement programs are generally less likely to survive than wild conspecifics. Digestion efficiency and naive behaviour are two likely reasons for this pattern. The Mallard is a species with high adaptability to its environment and in which massive reinforcement programs are carried out. We studied physiological and behavioural factors potentially affecting body condition and survival of captive-reared Mallards after being released. Digestive system morphology and an index of body condition were compared among three groups: captive-reared birds remaining in a farm (control), captive-reared birds released into the wild as juveniles (released) and wild-born birds (wild). We also compared behaviour and diet of released vs. wild Mallards. Finally, we conducted a 1-year survival analysis of captive-reared birds after release in a hunting-free area. Gizzard weight was lower in control Mallards, but the size of other organs did not differ between controls and wild birds. The difference in gizzard weight between released and wild birds disappeared after some time in the wild. Diet analyses suggest that released Mallards show a greater preference than wild for anthropogenic food (waste grain, bait). Despite similar time-budgets, released Mallards never attained the body condition of wild birds. As a consequence, survival probability in released Mallards was low, especially when food provisioning was stopped and during harsh winter periods. We argue that the low survival of released Mallards likely has a physiological rather than a behavioural (foraging) origin. In any case, extremely few released birds live long enough to potentially enter the breeding population, even without hunting. In the context of massive releases presently carried out for hunting purposes, our study indicates a low likelihood for genetic introgression by captive-reared birds into the wild population.

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Section: Discussionmentioning

confidence: 68%

Low survival after release into the wild: assessing “the burden of captivity” on Mallard physiology and behaviour

Guillemain

Elmberg

et al. 2011

Eur J Wildl Res

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“…'Soft releases' are often assumed to increase the initial survival of translocated animals (Kleiman 1989, Bright andMorris 1994), but some experiments have questioned this assumption (Armstrong and Seddon 2008). The hacking method that we used has been effective for the establishment of other populations of translocated raptors (e.g., Cade et al 1988, Cade and Jones 1993, Jones et al 1995, Hunt et al 2013, although the survival of hacked raptors can be lower than that of wild- reared birds (Kauffman et al 2003, Brown et al 2006. Regardless, because we only released juveniles, the translocation of wild-caught individuals and our use of hacking likely served to increase only juvenile survival.…”

Section: Discussionmentioning

confidence: 99%

Strategic monitoring of reintroductions in ecological restoration programmes

Ewen

Armstrong

2007

Ecoscience

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“…Studies to date of re‐introduced birds of prey do not show a clear picture: some indicate that released birds perform less well than wild‐bred ones (e.g. Brown et al. 2006), whereas others show no difference (Nicoll et al.…”

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confidence: 99%

Growth and demography of a re‐introduced population of White‐tailed Eagles Haliaeetus albicilla

Evans

Wilson

Amar

et al. 2009

Ibis

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White‐tailed Eagles Haliaeetus albicilla became extinct in Britain in 1918 following prolonged persecution. Intensive conservation efforts since the 1970s have included the re‐introduction of the species to Britain through two phases of release of Norwegian fledglings in western Scotland in 1975–85 and 1993–98. Population growth and breeding success have been monitored closely to the present day, aided by the use of patagial tags to individually mark most released birds as well as a high proportion of wild‐bred nestlings. This study reviews the growth and demography of this re‐introduced population, and makes comparisons with other European populations. For the first time, we compare the demographic rates of released and wild‐bred birds in the Scottish population. Breeding success in the Scottish population has increased over time as the average age and experience of individuals in the population have increased, and success tends to be higher where one or both adults are wild‐bred. Current levels of breeding success remain low compared with some other populations in Europe, but similar to those in Norway where weather conditions and food availability are likely to be most similar. Survival rates in Scotland are similar to those recorded elsewhere, but survival rates of released birds are lower than those of wild‐bred birds, especially during the first 3 years of life. Despite the effect of lower survival rates of released birds in limiting overall population growth rate, the recent rate of growth of the Scottish population remains high relative to other recovering populations across Europe. Differences in demographic rates of wild‐bred and released birds suggest that in future re‐introduction programmes, steps to maximize the success and output of the earliest breeding attempts would help ensure the most rapid shift to a population composed largely of wild‐bred birds, which should then have a higher rate of increase.

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Wild-reared aplomado falcons survive and recruit at higher rates than hacked falcons in a common environment

Cited by 47 publications

References 28 publications

Low survival after release into the wild: assessing “the burden of captivity” on Mallard physiology and behaviour

Low survival after release into the wild: assessing “the burden of captivity” on Mallard physiology and behaviour

Strategic monitoring of reintroductions in ecological restoration programmes

Growth and demography of a re‐introduced population of White‐tailed Eagles Haliaeetus albicilla

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