Data and code to analyze reproductive rates of California Condors in the first two decades of reintroduction in California

In the first comprehensive assessment of the reproductive rates of
critically endangered California Condors (Gymnogyps californianus)
recovering from complete extirpation in the wild, we analyzed 20 years
(1999–2018) of data from condor flocks in southern and central California.
We found that several anthropogenic threats affected reproductive rates:
(1) coastal space use by female condors was associated with lower hatch
probability, presumably due to marine mammal foraging and associated DDE
exposure, (2) trash ingestion by chicks decreased fledging probability
prior to implementation of trash management in 2007, and (3) all parent
deaths during rearing resulted in chick or early fledgling deaths, and
most parental deaths were due to lead poisoning. We also detected several
effects on reproductive rates of the complex individual-based management
of condors, which involves ongoing releases of captive-bred individuals
and health interventions including treatment of lead poisoning.
Recruitment rates were lower for new release sites, which we attribute to
a lack of individual- and flock-level experience. In addition, the number
of free-flying days in the wild was positively associated with female and
male recruitment and with female rebreeding probabilities, indicating that
removing individuals from the wild may reduce their breeding success.
Finally, probabilities of recruitment, rebreeding, and fledging all
increased with age, and given the age distribution skew of the recovering
flocks towards younger individuals, overall reproductive success was lower
than would be expected at the stable age distribution. Thus, reproductive
rates should increase over time as the mean age of California Condors
increases if current and emerging threats to reproduction, including the
loss of breeders due to lead poisoning, can be addressed.