Vulture carrion potential boon and threat for endangered Iberian lynx: Studies

During a study last year in Spain to assess scavenging by vultures, researchers made a surprising and unexpected find. A small number of Iberian lynx (Lynx pardinus), among the world’s most endangered feline species, readily feasted on the carcasses. According to the study authors, this is one of the first documented instances of such behavior, which could have both positive and negative conservation implications.

Researchers found that 12 out of 17 lynx present in the study area fed on carcasses, including two adults and a youngster who feasted at the same time. They also recorded some of the wild cats scent-marking some of the remains and, in some instances, trying to hide, or “cache,” their bounty. The researchers published the findings in the journal Biological Conservation.

On the one hand, the scientists believe this could be a “potential important resource” for the recovering species in areas where their natural prey, the endangered European wild rabbit (Oryctolagus cuniculus), is seriously depleted because of disease. But the behavior also has caused concern among conservationists, as carcasses can be vectors for disease or for contamination due to lead bullets or poison found in hunted animals.

“We thought this scavenging could be a problem for the lynx,” Jorge Tobajas, lead author of the paper with the University of Córdoba and Institute for Game and Wildlife Management, told Mongabay in an interview. “Maybe there is this overlooked effect of the scavenging behavior because until now the lynx was thought of as a specialist predator in Spain, preying mostly on rabbits.”

Jorge Tobajas and his team recorded Iberian lynx scavenging on carrion specifically placed out for vultures during a study. Such behavior could indicate a potentially positive conservation intervention, when the species’ natural prey is limited. But it could also pose a threat due to the risk of disease transmission. Image courtesy of Rafael Finat.

The European rabbit is the Iberian lynx’s preferred prey. Population declines, primarily due to disease outbreaks, are an ongoing challenge to lynx conservation. Image by Sergey Yeliseev via Flickr (CC BY-NC-ND 2.0).

Iberian lynx recovery

Twenty years ago, Iberian lynx numbers had dwindled to around 200 in the wild — driven to the precipice of extinction by habitat loss, persecution, and possibly by the decline of one of its primary prey species, the European rabbit, due to the introduction of viral hemorrhagic disease (VHD) in Spain. Conservationists feared the cat faced imminent extinction in the wild.

Today, after an extensive reintroduction program — consisting of the release of captive-bred individuals, rewilding, and prey recovery — there are more than 1,300 across the Iberian Peninsula, with the vast majority in Spain and smaller populations in Portugal. Lynx are now expanding their range and conservationists continue to work to connect populations.

The recovery is cause for celebration, says Alejandro Rodríguez, with the Doñana Biological Station, who has studied the Iberian lynx for several decades. In his view, such a rebound would not have been possible without sound scientific understanding of the species’ ecological needs, principally its close dependence on wild rabbits.

But Rodríguez believes it is important not to rest on these conservation laurels. “Recovering the number of lynx to similar levels we had 40 years ago is excellent, but there are still uncertainties about the species’ long-term conservation,” he wrote, adding that according to some estimates lynx numbers may still need to increase fourfold for the species to survive without intensive conservation attention.

Only 12 lynx in total were recorded scavenging carrion. Many questions remain about how rare such behavior may be across the wider population, and how much of a risk it poses. Image courtesy of Rafael Finat.

Jumping the fence

In a separate monitoring project carried out over two years in southern Spain, researchers found that lynx and other species, such as foxes, were entering vulture feeding stations to scavenge. These fenced structures are used widely across Spain to support avian scavenger populations, such as the griffon vulture (Gyps fulvus).

In the study area, only four lynx entered the feeding stations. But according to Carlos Rouco, a wildlife ecologist and associate professor at the University of Sevilla, it’s a cause for concern as there is potentially a high risk for transmission of diseases such as tuberculosis, Aujeszky’s disease (also known as pseudorabies), and hepatitis. Rouco, along with other researchers, recently published a paper detailing their concerns in response to Tobajas’s study.

Even though there are veterinary checks on such carcasses, they are often not sufficient to identify some diseases, Rouco said: “You actually have to collect samples and carry out analysis.

“In other areas where they are using these feeders, [people] should check to make sure they are not creating potential hotspots of pathogens,” he added. “The truth is that many species can actually get inside these feeding stations.”

It’s a situation that has to be approached with caution, however, according to Tobajas. “We shouldn’t be too alarmist,” he says, as any drastic action could negatively impact vulture conservation. Nonetheless, in their recent rebuttal to the paper by Rouco’s group, his research team agrees that the carrion situation requires further monitoring to understand if this lynx behavior is indeed rare or not.

Researchers monitoring vulture feeding stations in southern Spain found that Iberian lynx and other species scaled fences to scavenge on carcasses. They believe such behavior could pose a disease threat to the endangered felid and propose further investigations to identify if lynx in other areas are acting in similar ways. Image courtesy of Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ)/University of Córdoba, Spain.

For Rodríguez, who was not involved in either research project, multiple questions remain and the scavenging would only be a possible cause for concern if such behavior was found to be widespread among the wild cat.

“In my opinion, it is yet to be confirmed that scavenging of subsidized ungulate carrion by Iberian lynx is a general pattern,” Rodríguez wrote in an email to Mongabay. “If so, I would expect ungulate remains to appear quite often in lynx feces, but this has not been observed in diet studies carried out in areas where wild ungulates are very abundant.”

Such rare behavior can be imitated or learnt by offspring without necessarily spreading to wider populations, he added. “Ungulate carcasses resulting from hunting are typically removed, and whether carrion availability could be high enough to promote [lynx] scavenging needs to be closely examined.”

The researchers agree that further investigation is needed to identify whether this scavenging behavior truly exists, is widespread, and poses a real conservation threat. Rouco and his colleagues also suggest that steps could be taken as a precaution to “predator-proof” vulture feeding stations in Spain and elsewhere around the world where scavenging behavior by threatened terrestrial species is identified.

“A good [enclosure] design costs money,” he said. “So, it depends how much you want to invest in a proper fence that is proofed against other non-target species.”

Citations:

Tobajas, J., Finat, R., Ferreras, P., & Margalida, A. (2023) Iberian lynxes scavenging on ungulate carcasses: An overlooked important resource and potential risk for an endangered predator. Biological Conservation, 277, 109855. doi:10.1016/j.biocon.2022.109855

Gonzálvez, M., Jiménez-Ruiz, S., Paniagua, J., Rouco, C., & García-Bocanegra, I. (2023) Vulture feeding stations threaten Iberian lynx. Biological Conservation, 109960. doi:10.1016/j.biocon.2023.109960

Tobajas, J., Finat, R., Ferreras, P., & Margalida, A. (2023) Can vulture feeding stations have detrimental effects on Iberian Lynx conservation? Biological Conservation, 109971. doi:10.1016/j.biocon.2023.109971

This article by Sean Mowbray was first published by Mongabay.com on 4 April 2023. Lead Image: The Iberian lynx is a conservation success story. In the early 2000s, its numbers had dwindled to around 200. Today, after extensive conservation efforts, the species numbers more than 1,300 individuals. Image by Animal Record via Flickr (CC BY 2.0).

What you can do

Support ‘Fighting for Wildlife’ by donating as little as $1 – It only takes a minute. Thank you.

DONATE NOW

Fighting for Wildlife supports approved wildlife conservation organizations, which spend at least 80 percent of the money they raise on actual fieldwork, rather than administration and fundraising. When making a donation you can designate for which type of initiative it should be used – wildlife, oceans, forests or climate.