15–20 Viner, condor mortality

Over the past 30 years, the California condor (Gymnogyps californianus) population has rebounded from 22 individuals to more than 200 birds living in the wild. Historical impacts on the population have been mostly anthropogenic. In this study, we explore mortality and cause of death data from condors that died during the years 2010–2014 and compare these to mortality data described by Rideout et al. in 2012, covering the years 1992–2009. Also, morphologic and genetic analysis of the upper gastrointestinal (GI) tract contents was performed on the 2010–2014 condor mortalities to determine animal origins of the last meal eaten. The maximum population at risk within this time frame was 329 birds. During this time, 88 condors died and underwent postmortem examination, and 41 birds were lost to tracking efforts and presumed dead (39% crude mortality rate; 129/329). A cause of death was determined for 66 of the 88 necropsied birds. Lead toxicosis remained a significant negative factor in condor population recovery, being related to the deaths of 37 adult and juvenile condors (56% proportional mortality rate). Cattle were less often part of the last meal of lead-intoxicated condors than condors that succumbed to other causes of death. Based on these data, continued efforts to mitigate the impact of lead on California condors should be pursued.