Avian scavenger crisis - The urgent need to look in to the trophic cascades, and loss of critical ecosystem functions

The avian scavenger crisis: Looming extinctions, trophic cascades, and loss of critical ecosystem functions

Evan R. Buechley and Çağan H. Şekercioğlu

Biological Conservation

Volume 198, June 2016, Pages 220–228

Vultures are the most threatened group of birds, many of the species on the precipice of extinction.  Of the 22 vulture species, nine are critically endangered, three are endangered, four are near threatened, and six are least concern. Diet specialization and taxonomy are leading extinction risk predictors. Dietary toxins are main threat for 59% of all avian scavengers, 88% of vultures. Vulture declines is  expected to cause trophic cascades and disease outbreaks. Currently, 73% of vulture species are extinction-prone (near threatened, vulnerable, endangered, critically endangered and extinct) and 77% have declining populations. Against this backdrop only 13% of avian facultative scavenger species are extinction-prone and 70% have stable or increasing populations. As vultures decline, populations of many facultative scavengers are growing. This causes trophic cascades from increased predation, competition, and invasion. Vultures' highly specialized digestive systems efficiently eradicate diseases when consuming carrion, whereas facultative scavengers are more susceptible to contract and transmit diseases among themselves and to humans. The researchers urge immediate action, particularly by regulating lethal dietary toxins, to prevent the extinction of vultures and loss of respective ecosystem services.