Dispersal patterns of the endangered Crested Ibis suggest high breeding densities drive natal dispersal

Although dispersal is a key driver of population dynamics and species distributions, we still know little about how it affects the dynamics of endangered and restricted-range species. Density-dependent effects on dispersal, in particular, may be critical for range expansion of recovering populations. After 1981, when the last seven wild individuals of Crested Ibis Nipponia nippon were discovered in China, the species remained confined to a single location (‘original nesting area’ - ONA) until 2000 (< 24 breeding pairs). Then, the breeding population began a significant spatial and numerical expansion toward new breeding sites (‘secondary nesting areas’ - SNA). Our analyses of long-term (1993–2017) individual resighting data (n=193) found that natal dispersal is common (≈77.2%), while breeding dispersal is rare (≈2.1%). Breeding density was negatively related to productivity, and natal dispersal was more likely towards low-density areas. The Weibull distribution provided the best fit ..., , ,