TURKEY VULTURES (CATHARTES AURA) FROM SOUTHERN CALIFORNIA ARE EXPOSED TO ANTICOAGULANT RODENTICIDES DESPITE RECENT BANS

SAGGESE, MIGUEL D.; 8 AUTHORS; CASALINS, L.; OJEDA, V. ; POPPENGA, R.

JOURNAL OF RAPTOR RESEARCH

RAPTOR RESEARCH FOUNDATION INC

Lugar: Lawrence, Kansas; Año: 2024

0892-1016

Secondary poisoning with anticoagulant rodenticides (ARs) has been identified as animportant threat for raptor conservation worldwide. In 2019, the California StateLegislature passed Assembly Bill 1788, made effective in 2020, prohibiting or limitingthe use of second-generation Anticoagulant Rodenticides (SGARs) in the state, as afollow-up to the California Department of Pesticide Regulation banning of SGARimplemented in 2014. Currently, the adherence to these recent restrictions on ARs insouthern California is unknown. To assess if these bans prevented exposure of wildlifeto ARs, we investigated 1) the prevalence of exposure to eight different ARs in theblood of Turkey Vultures (Cathartes aura) before and after the 2019 ban, and 2) thedistribution of resights of wing-tagged Turkey Vultures included in this study to assesswhere exposure might occur. Of 27 Turkey Vultures tested for eight ARs, one out of 11sampled in 2017 had detectable (trace) but not quantifiable levels of difethialone, andtwo out of 16 (12.5%) sampled in 2021 had detectable levels of diphacinone (one had8 ppb, another indicated as positive without quantification). Overall, the prevalence ofexposure to ARs was 11.1 % (3 out of 27), 7.4% for diphacinone and 3.7% fordifethialone. Based on 93 resightings of 20 of our wing-tagged Turkey Vultures, all but one remained within the areas of Los Angeles, San Bernardino, Orange, Riverside andSan Diego counties of southern California. Our study suggests that the exposure risk ofTurkey Vultures to ARs persisted despite recent restrictions. Our small sample sizeand reliance on blood in live vultures rather than liver in deceased ones may beunderestimating true ARs exposure in our study population. We propose a continuedand integrated monitoring approach that includes ARs investigation in both freeranging(blood samples) and deceased (liver samples) Turkey Vultures for effectivelarge-scale monitoring. This approach will assess compliance with current and futurebans and regulations regarding the use of these poisons in California.