Unsustainable human activities and habitat loss have driven many of the world’s birds to near extinction – now one in eight bird species is under severe threat. According to the IUCN Redlist, at least 190 bird species are listed as ‘critically endangered’ meaning that there are likely fewer than 250 mature individuals remaining in the wild. Unfortunately, the status of the world’s bird species is steadily declining. More birds are either being added to the growing list of endangered species or being up-listed to higher levels of threat. It is estimated that 80% of the world’s bird species are currently in decline. Threats, such as deforestation, habitat conversion for agriculture, invasive species and persistent hunting, are continuing to push these species closer towards extinction.
Conservation action, including research and intensive management, too often is thought about only in the context of large-sized and attention-grabbing mammals. However, the Conservation Centers for Species Survival is both an advocate and practitioner for more actions directed at avian species; especially those that benefit from the consortium’s special care and space resources for husbandry management and its vast research experience. C2S2 member institutions and their collective skills already have helped to understand the basic biology of 15 bird species, which in many cases, has led to their successful recovery including their return to nature.
C2S2’s avian portfolio currently is focused on three North American birds, each protected under the Endangered Species Act: Attwater’s prairie chicken (a subspecies), masked bobwhite quail (subspecies) and whooping crane (species). All have experienced drastic population declines, mostly due to habitat loss, and each has two common characteristics – reliance on the need for ex situ (captive) breeding, and a goal to establish self-sustaining populations through reintroduction of animals back to nature. Each of the recovery programs associated with these subspecies/species has benefited from C2S2 advice or direct assistance. Partners have included the U.S. Fish & Wildlife Service (USFWS) and the U.S. Geological Survey (USGS).
Attwater’s prairie chicken (Tympanuchus cupido attwateri)
The Attwater’s prairie chicken is one of the most endangered birds in the U.S. with fewer than 100 individuals left in the wild, largely in the Attwater Prairie Chicken National Wildlife Refuge located in Colorado County, Texas. Attwater’s are endemic to the coastal prairie habitat found along the Gulf of Mexico, and require expanses of prairie habitat to carry out their life functions – shorter grasses for mating, taller grasses for nesting and cover. It is thought that the unique and elaborate mating rituals performed by the males serve as inspiration for traditional dances performed by some Native American Plains Indians. Nevertheless, loss and fragmentation of the critically important coastal prairie ecosystem has pushed this species to the brink of extinction. Since 1992, Fossil Rim Wildlife Center of C2S2 has worked with USFWS, supplying 955 birds for release as well as others to partner ex situ facilities in order to maintain the captive flock.
However, the challenges of recovering the Attwater’s prairie chicken go far beyond producing and releasing young. C2S2 has provided input on understanding the causes of mortality in the offspring of captive born birds that mate successfully in nature. We also have proposed the survival and reproductive benefits of mother-reared prairie chickens (and other bird species) in reintroduction programs – C2S2 has extensive experience in this arena. C2S2 specialists also have promoted the need for more habitat to create additional release sites to increase the chances of achieving self-sustainability for this subspecies. Lastly, Fossil Rim Wildlife Center and C2S2 are leading the development of a practical database to help identify and track the factors that help achieve breeding and reintroduction success. Such a system will have wide-ranging utility for other endangered species recovery programs.
Masked bobwhite quail (Colinus virginianus ridgwayi)
The masked bobwhite quail currently exists as a single population of about 500 individuals living in a captive facility in the Buenos Aires National Wildlife Refuge (BANWR) near the Altar Valley in Arizona. Birds may or may not remain in nature, but if so at extremely low density. This dark hooded, geographically distinct relative of the northern bobwhite is primarily found in grassy savanna habitats and dense grasslands. One of the major challenges to recovering the masked bobwhite quail is determining the suitability of the local habitat, including need for restoration and the identification of suitable future release sites. A related priority is understanding the quality of current quail population that has been in captivity for generations and ensuring its long-term viability.
Led by San Diego Zoo Global and Fossil Rim Wildlife Center, C2S2 is providing guidance and assistance to the Masked Bobwhite Quail Recovery Team, especially in assessing the viability and ensuring the sustainability of the captive flock. This can include design and staffing of a new facility at BANWR that will improve the intensive management environment and better allow retaining gene diversity to increase chances for successful subspecies reintroduction in both the U.S. and Mexico.
Whooping crane (Grus americana)
The whooping crane is one of the rarest birds in North America and is emblematic of wildlife conservation in the U.S. Standing at about five feet tall, the whooping crane is the tallest bird in North America and has a wingspan of nearly 8 feet. These cranes are also very long lived – up to 40 years, and form monogamous pair bonds. A damaging combination of habitat loss and over-hunting pushed this once popular bird to near extinction, with only 15 birds remaining in 1941. Captive breeding began in 1966 and the development of three breeding centers, along with substantial information on husbandry and reproductive biology has not only allowed the species to recover adequately, but also has permitted successful reintroduction in 2001. Currently, there are about 350 whooping cranes living in nature and about 150 in captive facilities. Reproductive technology, especially artificial insemination has played a key role in ensuring that sexually incompatible, but genetically appropriate pairs reproduce.
Because of the original small population, it is essential that every genetically valuable individual breeds to retain all remaining gene diversity. There also is a need to ramp up chick production to ensure adequate bird numbers for reintroduction.
C2S2 has been involved in both providing advice and direct assistance in the recovery program. Current emphasis has been on research collaboration with the Patuxent Wildlife Research Center in Laurel, MD. Led by C2S2 partner, the Smithsonian Conservation Biology Institute, this partnership is now exploring infertility that has been observed in certain birds. This work, which includes a shared graduate student, is benefiting from the extensive experience of C2S2 in semen quality assessments and fecal hormone monitoring to understanding fertility status. Identifying and correcting causes of low reproduction will help boost chick numbers available for reintroductions. C2S2 also is advising on the concept of mother-reared chicks as candidates for release.