How conservationists’ wing tags are actually endangering the Cape vulture
In a bid to save Cape vultures from extinction, conservationists fit them with wing tags. But a new study has found the tags are endangering the birds’ lives.
Researchers at the Max Planck Institute of Animal Behaviour in Germany and VulPro, a SA vulture conservation organisation, found that wing tags limit the movement and speed of vultures, compared with birds fitted with bands around their legs.
According to results published in the journal Animal Biotelemetry, conservationists have been fitting vultures with wing tags for over a decade.
The tags’ advantage is that they are large and “conspicuous enough for individuals to be identified from far away”. Smaller leg bands are “harder to notice and record the unique number”.
VulPro founder Kerri Wolter said: “After receiving many grounded and injured vultures from incorrect placement of wing tags, we felt there was an immediate need to find out exactly what these tags were doing to the flight of birds and whether this technique was, in fact, hindering the species rather than protecting them.”
Max Planck Institute researchers used GPS devices to track 27 Cape vultures
“marked with either patagial [wing] tags or leg bands”.
The GPS devices, which were mounted on the birds' backs, recorded the birds' positions as often as every minute for 24 hours a day, according to the study.
The recordings enabled the researchers to examine the birds' “flight performance, including occurrence of flight, proportion of time spent flying in a day, daily distance travelled and ground speed”.
Researchers observed that birds fitted with wing tags “covered a much smaller area in comparison to the leg band group”. They were less likely to take flight and, when doing so, flew at lower ground speed compared to individuals wearing leg bands.
“Though we did not measure the effects of patagial tags on body condition or survival, our results strongly suggest that patagial tags have severe adverse effects on vultures' flight performance,” said Max Planck research group leader Teja Curk.
The institute's Kamran Safi said vultures are scavengers, and by feeding on dead animals they play an important role in the ecosystem by preventing the spread of infectious diseases, recycling organic material into nutrients and stabilising food webs.
“Therefore, restricted flight potential and a reduction in the area covered by these birds, caused by improper tag attachment, can have far-reaching consequences at the ecosystem level,” he said.