LOW PREVALENCE OF HAEMOSPORIDIANS IN BLOOD AND TISSUE SAMPLES FROM HUMMINGBIRDS

Illuminating the Mysteries of the Smallest Birds: Hummingbird Population Health, Disease Ecology, and Genomics

Hummingbirds share biologically distinctive traits: sustained hovering flight, the smallest bird body size, and high metabolic rates fueled partially by nectar feeding that provides pollination to plant species. Being insectivorous and sometimes serving as prey to larger birds, they fulfill additional important ecological roles. Hummingbird species evolved and radiated into nearly every habitat in the Americas, with a core of species diversity in South America. Population declines of some of their species are increasing their risk of extinction. Threats to population health and genetic diversity are just beginning to be identified, including diseases and hazards caused by humans. We review the disciplines of population health, disease ecology, and genomics as they relate to hummingbirds. We appraise knowledge gaps, causes of morbidity and mortality including disease, and threats to population viability. Finally, we highlight areas of research need and provide ideas for future studies aimed at facilitating hummingbird conservation.

Diversity, distribution, and methodological considerations of haemosporidian infections among Galliformes in Alaska

Using samples spanning 10-degrees of latitude in Alaska, we provide the first comparative assessment of avian haemosporidia distribution of Arctic Alaska with subarctic host populations for four species of grouse and three species of ptarmigan (Galliformes). We found a high overall prevalence for at least one haemospordian genus (88%; N = 351/400), with spruce grouse (Canachites canadensis) showing the highest prevalence (100%; N = 54/54). Haemoproteus and Plasmodium lineages were only observed within grouse, while Leucocytozoon species were found within both grouse and ptarmigan. Further, different Leucocytozoon lineages were obtained from blood and tissue samples from the same individual, potentially due to the differential timing and duration of blood and tissue stages. Using different primer sets, we were able to identify different Leucocytozoon lineages within 55% (N = 44/80) of sequenced individuals, thereby detecting coinfections that may have otherwise gone undetected. The commonly used Haemoproteus/Plasmodium primers amplified Leucocytozoon for 90% (N = 103/115) of the products sequenced, highlighting the potential value of alternate primers to identify intra-genus coinfections and the importance of obtaining sequence information rather than relying solely on PCR amplification to assess parasite diversity. Overall, this dataset provides baseline information on parasite lineage distributions to assess the range expansion associated with climate change into Arctic regions and underscores methodological considerations for future studies.

Prevalence and diversity of haemosporidians in a migratory high-elevation hummingbird in North America

Hummingbirds (Trochilidae) are sensitive to environmental changes because of their extraordinary ecology, metabolism, and the highest red blood cell counts found in any vertebrate. These physiological attributes may render hummingbirds particularly susceptible to the effects of haemosporidian (blood parasite) infections. Much of the research on haemosporidians in hummingbirds has been conducted in South America; less is known about haemosporidian diversity and prevalence in North America. We sought to determine the prevalence and diversity of haemosporidians in a high-elevation species, the Broad-tailed Hummingbird (Selasphorus platycercus). Blood samples (N = 314) from 25 sites in Colorado and Wyoming were screened for haemosporidians using microscopy (n = 311) and PCR (n = 301). Both microscopy and sequencing diagnostic techniques detected haemosporidians in the same 5 hummingbirds, with an overall prevalence of 1.59%. Positive samples were sequenced at the cytochrome b gene and identified Haemoproteus archilochus and two Haemoproteus sp. not previously detected in North America. No parasites of the genera Plasmodium or Leucocytozoon were detected. Our study provides the first report of the prevalence and diversity of haemosporidians in Broad-tailed Hummingbirds in the Rocky Mountains.