Pesticides: The most threat to the conservation of the Andean condor (Vultur gryphus)

Highlights

• Pesticide poisoning is currently the greatest threat to the Andean condor.

• Poisonings affect adult condors more than immature ones.

• The most commonly used poison is Carbofuran, and to a lesser extent Palation.

• Condor poisonings have reached alarming levels that could lead to extinction.

Introduction

Within human-wildlife conflicts, the use of poisoned carcasses to control predators has worried the international scientific and conservation community, due to the serious consequences it has on natural populations and their ecosystems. In many countries it is illegal and there is evidence that it affects a large number of non-target species (Mateo-Tomás et al., 2012; Woodroffe et al., 2005). Among the species most susceptible to this practice are the vultures, because they are specialized scavengers being more susceptible to consuming poisoned carcasses (Márquez et al., 2012). This, altogether with other threats, is declining the natural populations of vultures in almost all the world (Buechley and Şekercioğlu, 2016; McClure et al., 2018; Ogada et al., 2016). There is a great deal of evidence of this threat and its effect on wildlife in Europe, Asia and Africa (Cano et al., 2016; Loveridge et al., 2018; Murn and Botha, 2017). However, there are no studies about vulture poisoning or their effect they may have on natural populations in South America.

The Andean Condor (Vultur gryphus) is the largest scavenging bird and is endemic to South America. The species' range extends across the Andean mountains from sea level to heights >7000 m (Ferguson-Lees and Christie, 2001; Jácome et al., 2005). Currently the species is considered as “Near Threatened” worldwide and populations are declining due to anthropic causes (BirdLife, 2019). The global population is estimated at 6700 mature individuals in the entire distribution area with populations descending from south to north (BirdLife, 2019). For Argentina, there are no population estimates so far, only some local estimates (Cailly-Arnulphi et al., 2013; Gargiulo, 2012; Lambertucci, 2010). According to the Ministerio de Ambiente y Desarrollo Sustentable de la Nación (MAyDS) and Aves Argentinas (AA), the species is considered “Threatened” due to population reductions. Because condors cross the international border between Argentina and Chile daily, flying up to 300 km/day and with very large home ranges that can reach up to 53,000 km² (Lambertucci et al., 2014), individuals from these countries are often considered a single population (Cuesta, 2000).

The conservation concerns that affect condors are similar to those that other vultures in the world (Lambertucci and Speziale, 2009). Although lead poisoning is being widely studied (Plaza et al., 2018; Plaza and Lambertucci, 2019; Wiemeyer et al., 2017) poisonings due to the consumption of carrion poisoned by cattle ranchers and the effect that this practice can have on the natural populations of condors, has not yet been addressed.

In Argentina, since August 1991, the Andean Condor Conservation Program (PCCA) has been working on the integral conservation of this species (Jácome and Astore, 2016). Among its main lines of action, in 2001, the Andean Condor Rescue Center (CRCA) was created, dedicated to the rescue and rehabilitation of wild condors throughout the country. The CRCA, thanks to collaboration agreements with the Secretaries of National and Provincial Environment, National Gendarmerie, National Parks Administration and with the support of Rural Police, was able to carry out rescued condors in the 14 provinces where this species lives. In each province first aid is given to the rescued specimens and, once stabilized, they are derived, through Aerolineas Argentinas, to the rehabilitation and breeding centers in human isolation of the PCCA that operate in Buenos Aires City (Ecoparque Bs As), Escobar (Foundation Temaikèn) and in San Carlos, Mendoza (Foundation Cullunche) to complete their rehabilitation protocol. In the framework of the PCCA, both the specimens from the parental and artificial breeding program, as well as the specimens rehabilitated by the CRCA, are derived to in situ conservation plans being released in natural environments, taking into account their flight experience (Astore et al., 2017).

In this paper, we analyze the records in the Andean Condor Rescue Center (CRCA) since its creation to the present, in order to study the casuistry associated with poisoned carcasses. The specific aims are i) to determine if the sex and age of the specimens are related to poisoning, ii) to identify temporal and spatial factors associated with poisoning and iii) to calculate the rate of poisoning from condors released and tagged with GPS-satellite transmitters.