Bertram, Miranda Rose (2016-08). Disease Risks to Whooping Cranes (Grus americana) Determined by Non-invasive Sampling and Use of the Sandhill Crane (Grus canadensis) as a Surrogate. Doctoral Dissertation. Thesis uri icon

abstract

  • The only self-sustaining wild population of endangered whooping cranes (Grus americana) has grown to approximately 308 individuals. However, the population growth is not consistent with species recovery goals, and the impact of parasite infection on whooping crane populations is largely unknown. Our goal was to quantify the prevalence of fecal parasites and hemoparasites in whooping cranes and to compare the prevalence of infection between whooping and sandhill cranes (Grus canadensis). We assessed the prevalence and phenology of Eimeria oocysts in whooping crane fecal samples collected across two winter seasons (November 2012 - April 2014) at the Aransas National Wildlife Refuge along the Texas Gulf coast. Across both years, 26.5% (n=328) of fecal samples were positive for Eimeria based on microscopy. We noted nematode eggs in 30% (n=327) and 2.7% (n=75) of whooping and sandhill crane fecal samples, respectively. However, sequences from these samples aligned with soil-dwelling nematodes, indicating environmental contamination. We noted trematode eggs in 11.1% (n=63) and 50% (n=20) of whooping and sandhill crane samples, respectively. We identified three species of trematode, one cestode, one acanthocephalan, and one nematode in sandhill cranes on necropsy. Orchipedum jolliei was the most common trematode and was noted in 42% (n=108) of sandhill cranes. The prevalence of O. jolliei was significantly higher in sandhill cranes wintering along the Texas Gulf Coast than in the Texas panhandle or New Mexico. We used three different PCR assays to screen samples for Haemosporida and detected an infection prevalence of 59.5% (n=163) across all birds. Infection prevalence was high in whooping cranes and sympatric sandhill cranes, but significantly lower in allopatric sandhill cranes. Haemoproteus antigonis was present in 46% of samples from both crane species and was phylogenetically distinct from other avian Haemosporida. We demonstrate that non-invasive fecal collections combined with PCR and DNA sequencing techniques provides a useful tool for monitoring coccidia and helminth infection in cranes. We also document a high prevalence of H. antigonis in whooping cranes and sympatric sandhill cranes, supporting the use of sandhill cranes as a surrogate species for understanding health threats to the endangered whooping crane.
  • The only self-sustaining wild population of endangered whooping cranes (Grus americana) has grown to approximately 308 individuals. However, the population growth is not consistent with species recovery goals, and the impact of parasite infection on whooping crane populations is largely unknown. Our goal was to quantify the prevalence of fecal parasites and hemoparasites in whooping cranes and to compare the prevalence of infection between whooping and sandhill cranes (Grus canadensis).

    We assessed the prevalence and phenology of Eimeria oocysts in whooping crane fecal samples collected across two winter seasons (November 2012 - April 2014) at the Aransas National Wildlife Refuge along the Texas Gulf coast. Across both years, 26.5% (n=328) of fecal samples were positive for Eimeria based on microscopy. We noted nematode eggs in 30% (n=327) and 2.7% (n=75) of whooping and sandhill crane fecal samples, respectively. However, sequences from these samples aligned with soil-dwelling nematodes, indicating environmental contamination. We noted trematode eggs in 11.1% (n=63) and 50% (n=20) of whooping and sandhill crane samples, respectively. We identified three species of trematode, one cestode, one acanthocephalan, and one nematode in sandhill cranes on necropsy. Orchipedum jolliei was the most common trematode and was noted in 42% (n=108) of sandhill cranes. The prevalence of O. jolliei was significantly higher in sandhill cranes wintering along the Texas Gulf Coast than in the Texas panhandle or New Mexico.

    We used three different PCR assays to screen samples for Haemosporida and detected an infection prevalence of 59.5% (n=163) across all birds. Infection prevalence was high in whooping cranes and sympatric sandhill cranes, but significantly lower in allopatric sandhill cranes. Haemoproteus antigonis was present in 46% of samples from both crane species and was phylogenetically distinct from other avian Haemosporida.

    We demonstrate that non-invasive fecal collections combined with PCR and DNA sequencing techniques provides a useful tool for monitoring coccidia and helminth infection in cranes. We also document a high prevalence of H. antigonis in whooping cranes and sympatric sandhill cranes, supporting the use of sandhill cranes as a surrogate species for understanding health threats to the endangered whooping crane.

publication date

  • August 2016