Survival of Sooty Falcons (Falco concolor) breeding in Oman

Abstract

Although the Middle East supports a high level of avian biodiversity, the ecology of relatively few species that use the region has been studied in detail. Despite its restricted breeding distribution in the Middle East, and apparent unfavorable conservation status, little is known about the population ecology of the Sooty Falcon (Falco concolor), one of only two falcon species that breeds in the boreal summer. We applied multi-state models to capture-mark-recapture data collected during 2007-2014 in the Sultanate of Oman to estimate, for the first time, the probabilities of capture, age-specific breeding probabilities, and state-specific apparent survival for Sooty Falcon. Capture probability for breeding adults (±1SE) was 0.443 ± 0.088. Annual apparent survival probability for pre-breeders and for breeding adults was 0.570 ± 0.048 and 0.656 ± 0.069, respectively. The probability that 2-, 3-, and 4-year-old falcons returned as breeders was 0.065 ± 0.036, 0.159 ± 0.069, and 0.339 ± 0.211, respectively. In 2013, we radio-tagged five fledgling falcons, and monitored their fates using satellite-based tracking. All initiated their first migration and survived for 48 days following radio-tagging, but four of the five birds died by 70 days post-tagging; only one survived > 100 days. Our results suggest that only about 12 % of fledglings survive to the average age of first breeding (~3.8 years), and that most of first-year mortality occurs during their first migration or soon after they reach their destination. Low apparent survival of pre-breeders could result in low recruitment to the breeding population, and population declines. A comprehensive population-level assessment is urgently needed to accurately determine the status of Sooty Falcons, and to devise flyway-scale conservation plans.