Anthropogenic mortality threatens the survival of Canarian houbara bustards

Abstract

Anthropogenic mortality is a major cause of global mortality in terrestrial vertebrates. Quantifying its impact on the dynamics of threatened species is essential to improve their conservation. We investigated cause-specific mortality in Canarian houbara bustards (Chlamydotis undulata fuertaventurae), an endangered subspecies endemic to the Canary Islands. We monitored 51 individuals tagged with solar-powered GSM/GPRS loggers for an average of 3.15 years, and recorded 7 casualties at aerial lines (13.73% of the sample; 5 at power lines, 2 at telephone lines), 1 (1.96%) at a wire fence, 4 road kills (7.84%) and 1 case of predation by cat (1.96%). Cox proportional hazards models showed that anthropogenic and natural annual mortality rates were similar (respectively, 6.20% and 6.36% of the individuals). We estimate that 33–35 houbaras die each year in the Canary Islands due to anthropogenic causes. Population viability models using these data and juvenile productivity values obtained over seven years predicted the extinction of the species in 50 years. Eliminating anthropogenic mortality, the population could be recovered, but would still require management actions to improve habitat quality. Conservation measures to reduce anthropogenic mortality due to power line fatalities, roadkills and predation by cats, as well as to increase productivity, are urgently needed, particularly on Fuerteventura, where houbaras are on the brink of extinction.

Blunt Force Trauma in the Canarian Houbara Bustard (<em>Chlamyd-Otis Undulata Fuertaventurae</em>) Produced by Collision with Over-Head Lines

“…The state of decomposition was established during necropsy, resulting in 7 animals being fresh, and 2 carcasses were incipiently decomposed. 7 of the 9 animals ported a GPS transmitter attached to the back with elastic bands included in another study performed by the Natural Sciences History Museum of Madrid (CSIC) [1]. Two cases were found under a high-voltage power line, whereas the remaining animals were found near medium-voltage electric lines or phone lines (case 2).…”

“…power lines, phone lines, telegraph wires, etc.) caused by collision and electrocution has been linked to decline of diverse avian species around the world [1][2][3][4]. However, most studies report estimation of mortalities due to power line collisions by documentation of the presence of carcasses along the electric or communication lines, and confirmation of trauma with standardized necropsies are not so commonly performed [2][3][4][5][6].…”

“…Although overhead lines constitute a possible hazard for all birds during flight, certain species, such as the bustards, tend to be more predisposed to collision [1,8,9].…”

“…The Canarian houbara bustard (Chlamydotis undulata fuertaventurae) is an endemic subspecies of houbara located in Fuerteventura, Lanzarote and La Graciosa in the Canarian Archipelago (Spain) [10] that has been closely monitored during the last years by different scientists [1,10,11]. This subspecies is considered "in danger" on the Spanish Red List [11] and as "vulnerable" by the IUCN (2009) [12], with an estimated population of 525-750 individuals according to different authors [1,11,13,14]. Power line collisions have been recognized as a significant problem for the conservation of these animals [1,6] and recent investigations predict the extinction of the subspecies in 50 years due to anthropogenic mortality [1].…”

“…This subspecies is considered "in danger" on the Spanish Red List [11] and as "vulnerable" by the IUCN (2009) [12], with an estimated population of 525-750 individuals according to different authors [1,11,13,14]. Power line collisions have been recognized as a significant problem for the conservation of these animals [1,6] and recent investigations predict the extinction of the subspecies in 50 years due to anthropogenic mortality [1].…”