When conservation management becomes contraindicated: impact of food supplementation on health of endangered wildlife

Abstract

Understanding the conditions that force the implementation of management actions and their efficiency is crucial for conservation of endangered species. Wildlife managers are widely and increasingly using food supplementation for such species because the potentially immediate benefits may translate into rapid conservation improvements. Supplementary feeding can also pose risks eventually promoting undesired, unexpected, subtle, or indirect, and often unnoticed, effects that are generally poorly understood. For two decades, intensive food supplementation has been used in attempting to improve the breeding productivity of the Spanish Imperial Eagle, Aquila adalberti, one of the most endangered birds of prey in the world. Here, we examined the impact of this intensive management action on nestling health, including contamination, immunodepression, and acquisition of disease agents derived from supplementation techniques and provisioned food. Contrary to management expectations, we found that fed individuals were often inadvertently "medicated" with pharmaceuticals (antibiotics and antiparasitics) contained in supplementary food (domestic rabbits). Individuals fed with medicated rabbits showed a depressed immune system and a high prevalence and richness of pathogens compared with those with no or safe supplementary feeding using non-medicated wild rabbits. A higher presence of antibiotics (fluoroquinolones) was found in sick as opposed to healthy individuals among eaglets with supplementary feeding, which points directly toward a causal effect of these drugs in disease and other health impairments. This study represents a telling example of well-meaning management strategies not based on sound scientific evidence becoming a "contraindicated" action with detrimental repercussions undermining possible beneficial effects by increasing the impact of stochastic factors on extinction risk of endangered wildlife.

Diversionary feeding: an effective management strategy for conservation conflict?

“…Poor food quality can also promote disease occurrence. Spanish imperial eagle (Aquila adalberti) populations receive supplementary food to increase breeding productivity, but the use of domestic rabbits containing high levels of antibiotics and anti-parasitic drugs causes higher pathogen abundance and a depressed immune system compared to those fed with wild rabbits (Blanco et al 2011). Supplemental feeding is often used as a 'quick fix', with little attention to long-term consequences for the target species (Blanco 2006).…”

Carcass Provisioning to Support Scavengers: Evaluating a Controversial Nature Conservation Practice

“…Third, as well as potential competition arising within the guild of avian scavengers, more local effects such as increased predation of ground nesting birds near feeding stations was recorded (Cortés-Avizanda et al 2009b). Fourth, there is concern that vulture health may be adversely affected by the consumption of medicated livestock as was shown for Spanish Imperial Eagles Aquila adalberti (Blanco et al 2011). However, the impact of vulture feeding stations was shown in some cases to be beneficial to non-target species, for example supporting rare carrion feeding invertebrates (Martín-Vega and Baz 2011).…”

Effect of supplementary feeding on reproductive success of hihi (stitchbird, Notiomystis cincta) at a mature forest reintroduction site

“…Shea 1998;Blanco et al 2011;Ewen et al 2015). The need for supportive management can be particularly true for reintroduced populations because their small population size during establishment makes them particularly vulnerable to stochastic extinction and potentially Allee effects (Converse et al 2013).…”

“…The use of supplementary food is not always accompanied by critical evaluation of its need or success at improving population growth (Oro et al 2008;Blanco et al 2011) however, and this has led to supplementary feeding being criticised as a dogmatic approach in conservation (Martinez-Abrain & Oro 2013). In addition, some studies have reported negative effects on the species being fed, or on other species in the wider recipient ecosystem (Pérez-González et al 2010;Blanco et al 2011;Robb et al 2011).…”

“…In addition, some studies have reported negative effects on the species being fed, or on other species in the wider recipient ecosystem (Pérez-González et al 2010;Blanco et al 2011;Robb et al 2011). In addition, conservation of threatened species is costly and funding is limited; so managers need to critically evaluate how resources are allocated against the objectives of management (Armstrong et al 2007).…”