: Reintroduction of captive‐reared animals has become increasingly popular in recent decades as a conservation technique, but little is known of how demographic factors affect the success of reintroductions. We believe whether the increase in population persistence associated with reintroduction is sufficient to warrant the cost of rearing and relocating individuals should be considered as well. We examined the trade‐off between population persistence and financial cost of a reintroduction program for Crested Coots (Fulica cristata). This species was nearly extirpated from southern Europe due to unsustainable levels of hunting and reduction in amount and quality of habitat. We used a stochastic, stage‐based, single‐sex, metapopulation model with site‐specific parameters to examine the demographic effects of releasing juveniles or adults in each population for a range of durations. We parameterized the model with data from an unsuccessful reintroduction program in which juvenile captive‐bred Crested Coots were released between 2000 and 2009. Using economic data from the captive‐breeding program, we also determined whether the strategy that maximized abundance coincided with the least expensive strategy. Releasing adults resulted in slightly larger final abundance than the release of nonreproductive juveniles. Both strategies were equally poor in achieving a viable metapopulation, but releasing adults was 2–4 times more expensive than releasing juveniles. To obtain a metapopulation that would be viable for 30 years, fecundity in the wild would need to increase to the values observed in captivity and juvenile survival would need to increase to almost unity. We suggest that the most likely way to increase these vital rates is by increasing habitat quality at release sites.
This short communication reports on the first record of Audouin's Gulls Larus audouinii breeding in captivity and on the behaviour of some individuals released as fledglings. During the period 1995-2000 a hand-reared male returned to its natal site and responded, year after year, to the translocation of a captive group of Audouin's Gulls for nesting site selection. The potential role of philopatry and conspecific attraction as conservation tools for this vulnerable seabird after an eight year experiment are discussed.
Ecological traps, in combination with other factors, can reduce population sizes and even lead to local extinction. Here, we present the first evidence that hunting sites can act as ecological traps for waterfowl: wintering common coots Fulica atra were preferentially attracted to hunting sites in southern European wetlands, and showed decreasing population trends in these sites, compared to non-hunting sites. We demonstrate that the supply of energy-rich supplementary food (grain) triggered the trap. We also show that a behavioural mechanism, acting as an evolutionary load (the tendency to form mixed coot flocks during the winter), decreased population size of a threatened waterfowl species, the crested coot F. cristata. Our results suggest the use of precautionary policies regarding supplementary food in coot and associated diving-duck species, if negative conservation impacts are to be avoided.
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