Epidemiological study of a reintroduction project: northern bald ibis (Geronticus eremita)

Epidemiological study of a reintroduction project: northern bald ibis (Geronticus eremita)

Yolanda RamiroMuseo del Jade

Yolanda Ramiro, Maricruz Camacho, Miguel A. Quevedo, Íñigo Sánchez, José Manuel López, Ursula Höfle

The Northern Bald Ibis is one of the most threatened bird species in the world. Fortunately, a reintroduction project in southwestern Spain has been successfully accomplished generating a breeding colony. Yearly, new zoo-reared juveniles are released for reinforcing this population and offspring of the independent free-living colony are ringed. This creates an exceptional opportunity to compare the different pathogen exposure of nestlings from two origins: an epidemiological hotspot as a zoo (avian/human pathogens), and a natural environment (wetland/migratory bird passage). We evaluated the health status of these populations and hypothesized that the captive-reared bird introduction could lead to a potential risk to the wild population. Blood samples and cloacal swabs were taken from nestlings from the free-living colony (n=21) and Jerez-Zoo (n=25). We tested the exposure to several viruses by commercial blocking ELISAs, and the presence of avian enterobacteria by multiplex PCR. All Escherichia coli isolates were phenotypically screened for resistance against antibiotics. All procedures were carried out under the guidelines and animal welfare ethical code of the Regional government. Hand-raised nestlings showed a significantly higher avian pathogenic E. coli (APEC) prevalence (44%) than free-living nestlings (5%; p<0.01). While Samonella spp. was not isolated. Gentamicin resistance of E. coli was significantly more frequent in hand-reared (80%) than in wild nestlings (50%; p<0.05).  West Nile Virus seroprevalence was significantly higher in free-living (86%) than in captivity nestlings (52%; p<0.05). The prevalence of antibodies against Newcastle Disease Virus was 100% in both populations. However, Avian Influenza Virus antibodies were only detected in hand-reared nestlings (8%). The results confirm the Flaviviruses exposure on wild ibis, and the risk of acquiring APEC and resistant bacterial strains in captive settings. Thus, this work shows the importance of health-screening in ex-situ conservation programs, and the use of monitored populations of reintroduction projects in wildlife health surveillance.

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