Renesting Propensity of Reintroduced Eastern Migratory Whooping Cranes

Laying additional clutches of eggs, or renesting, can provide birds with more opportunities to breed each season, ultimately increasing reproductive potential. This is important for long-lived species like cranes, that produce relatively few offspring annually. The reintroduced Eastern Migratory Population (EMP) of endangered Whooping Cranes relies on releases of captive-reared juveniles for population growth. Using long-term nest monitoring data, we assessed the renesting propensity of 105 unique pairs of Whooping Cranes during 2005–2024 (n = 359). We used a two-tiered analysis of binomial generalized linear mixed-effects models to evaluate the effects of 15 individual covariates, related to parental age or experience, nest management geography, or chronology. Overall, 37.3% of pairs renested following failed first nesting attempts. We documented higher renesting rates from breeding females that were older or had more years of nesting experience (37.1% increase for each unit increase in female age), pairs outside of the regions in which captive-reared cranes were released (264.0% increase in “other” region compared to Necedah), or that had nests fail earlier in the season (10.1% decline for each day later in the season a first nest failed). Additionally, when eggs were collected from first nests as a part of nest management, pairs were more likely to renest (69.4% renested) than if their nest failed naturally (27.3% renested). Low rates of natural reproduction limit growth rates in the EMP, so understanding effects of management actions and limitations on breeding are important conservation tools which can be applied to other endangered species.