Conservation medicine, sustainability, and welfare of an iconic bird: a review of whooping cranes from North America

The whooping crane (WCHR) has returned from the brink of extinction, but remains endangered despite over 40 years of concerted conservation action. The results of a recently completed multi-year health assessment of the... [ view full abstract ]

The whooping crane (WCHR) has returned from the brink of extinction, but remains endangered despite over 40 years of concerted conservation action. The results of a recently completed multi-year health assessment of the Central Flyway population highlight differences from both captive and reintroduced populations that could signal concerns. We found cutaneous chondromas present on 5% of adults; this condition has only been observed in 0.1% of wild sandhill cranes (SACR) from Florida. Seroprevalence to infectious bursal disease virus (IBD) was 70% in adults, compared to 15% in captive adults, 20% in reintroduced migratory adults from the eastern US, and 75% in reintroduced non-migratory cranes from Florida (a population with a history of outbreaks of clinical wasting syndrome and mortality consistent with IBD). Hemosporidia prevalence was 84% compared to 64% in sympatric SACRs, and prevalence of Plasmodium was significantly greater in WHCR (30%) than SACR (7%). Coccidial oocysts were observed in 26% of fecal samples from wintering cranes in Texas, and frequent concentrations of birds at fresh water sources occur during drought periods. Problems with the other strategies for recovery, ex situ captive breeding and reintroduction, are just emerging. Though the captive population of North America is well managed, appears stable, and has few problematic disease concerns, the offspring used for reintroductions may now be limited for success due to inadvertent captive selection and lack of learned behaviors that foster adaptation to the transformed landscapes available to reintroduction programs. An additional direct threat is a recent spate of illegal shootings of WHCRs, which is most destructive to the small, reintroduced populations in the eastern and southern US (13 known incidents since 2010). These phenomena have long-term consequences for overall population viability, and further increase the welfare concerns and human dimensions involved in conservation of one of North America’s most iconic birds.