Solutions for Vulture Diseases

Alternatives to diclofenac have been suggested (Gross 2006). The main objective has been to find an anti-inflammatory drug that could treat livestock without killing vultures. For example, toxicologist Gerry Swan and a team from South Africa, Namibia, India, and the United Kingdom argued for meloxicam treatment as an alternative (Swan et al. 2006). Meloxicam was the only NSAID that gave no evidence of kidney damage in vultures. This compound was tested on the African White-backed vulture, which has similar reactions to diclofenac as the Indian vultures. The results showed statistically significant differences in meloxicam and diclofenac. All vultures with the former lived and all those with the latter from a previous study died. The diclofenac-treated vultures had a marked and dose-dependent elevation of uric acid levels compared to controls; meloxicam-treated vultures showed no such differences. The authors acknowledged the small size of the sample and could not rule out the possibility of risk from the safer drug. A study of a larger number of wild and captive White-backed vultures and also Asian vultures affirmed this result. The conclusions were that 'meloxicam is of low toxicity to Gyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India' (Swan et al. 2006: 0395).

Another solution is the development of 'Vulture Restaurants'; places where carcasses are provided for vulture feeding (Clements et al. 2012). These are located in several countries; for example in Europe (Sarrazin et al. 1994; Carrete et al. 2006); Israel (Meretsky and Mannan 1999); and in some African countries (Mundy et al. 1992; Piper et al. 1999). The first such restaurant was developed in Giants Castle Game Reserve in the high Drakensberg of Natal, South Africa in 1966 for Bearded and Cape vultures (Friedman and Mundy 1983). Similar structures have also been developed for condors in North America (Wilbur et al. 1974). The impacts on vultures may be positive or negative, varying regionally depending on contextual factors (Piper 2006).

The provision of safe food benefits vultures (Gilbert et al. 2007; Oro et al. 2008). Other positive impacts include improved survival rates for adults and young (Oro et al. 2008), and possibly improved nesting success (see Gonzalez et al. 2006 for a study of the Spanish Imperial Eagle) although this may vary (e.g., a study by Margalida 2010 for the Bearded Vulture). Piper (2004a: 218) lists positive actions that benefit vultures, which are commented on by other researchers. These include supplementary food provision (Verdoorn 1997b; van Rooyen et al. 1997); provision of bone fragments as a source of calcium supplementation, which reduces osteoporosis (Mundy and Ledger 1976; Richardson et al. 1986); the provision of poison-free food; the attraction of vultures back to previous habitats, as in the case of Cape Griffon, African White-backed, Bearded and Lappet-faced Vultures (Verdoorn 1997b); stabilizing of vulture populations, for example increased nestling survival for Cape griffons (Piper et al. 1999); and hypothetically diverting vultures from lamb-predation (Verdoorn 1997b).

Negative results may occur when some species are favored by superior adaptation or dominance over others (see Margalida 2010; Moreno-Opo et al. 2010). For example the highly social Gyps species may dominate other more solitary vultures (Cortes-Avizanda et al. 2010; see Chapter 1 of this book for a discussion of the sociality of the Gyps vultures). The predictable artificial feeding may also encourage expectation from vultures, possibly changing their behavior (Robb et al. 2008). A possible result would be the alteration of vulture behavior to suit the new pattern (Deygout et al. 2010; Zuberogoitia et al. 2010), affect fecundity (Carrete et al. 2006). A possible solution would be varying the locations and dates of the restaurants, to avoid adaptation (Deygout et al. 2009; Clements et al. 2012). Piper (2004a: 218; see also Piper 2004b) lists negative effects of restaurants. These are: injuries due to fences; the attraction of unwanted species to vulture restaurants, including feral and domestic dogs, Black-backed jackals, Brown hyenas, mongoose spp., porcupines, chacma baboons, warthogs, bushpigs and fly spp., rare cases of cattle illness due to eating bones (i.e., osteophagy); meat theft by local people; power-line collisions and electrocutions when close; bird drownings in reservoirs especially in dry areas; and poisons in the meat, e.g., barbiturates or non-steroidal anti-inflammatory drugs (NSAID's) (Oaks et al. 2004).

Another solution is more effective monitoring. Danielsen et al. 2008 point out that for successful monitoring, accurate data must be compiled at the level of precision required to detect population changes in a particular context at a particular magnitude. The technical, logistical and financial expertise must be available. In some cases such resources are unavailable. For example, in India monitoring of vultures is usually done using road surveys (Prakash et al. 2007), but Clements et al. (2012) noted that in Cambodia the population density of vultures was too low for this method to be effective and the roads were few in areas of vulture habitat. Capture- mark resighting methods were also ineffective, as few vultures could be captured. Also, counting of nest sites does take into account the visibility of the nests. Counting of vultures that visit the vulture restaurants is also problematic, because the number of vultures not attending the feeding points is not known.

Clements et al. (2012) note that increased numbers of vultures recorded in a census might imply three possibilities: increased habitation to regular artificial feeding, declining food sources in other places, or an increasing population. The most important point is the possibility that vultures are habituated to the supplemental feeding sites. This means that more would be counted at these sites, even if the total population remained unchanged. Other factors may also be important. For example, comparing the vultures species that might attend a vulture restaurant in Cambodia, Clements et al. (2012) point out that the Red-headed vulture has a more varied diet than the White-rumped vulture and Slender-billed vulture, preying in some instances on live prey such as reptiles (see also Naoroji 2007). On this point they are therefore less likely to be dependent on vulture restaurants. They may also be more territorial and therefore the location of the feeding centres may be relevant.