Migrant Landbird Study Group

Promoting collaborative research for migratory landbirds across flyways

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Impact of Trichomonas gallinae infection on Turtle Doves

Study species: Turtle Dove

Research topic: Breeding ecology

Project organiser: Rebecca Thomas

Status: Active

Turtle doves are undergoing huge populations declines- most notably in the UK. Although this UK decline can be attributed to a reduction in breeding productivity and a lack of nesting habitat, a high prevalence of Trichomonas gallinae infection was found in a sample of this population during the breeding season of 2011.

Trichomonas gallinae is a protozoan parasite that lives in the mouth cavity. oesophagus and crop of a bird. Infection can be sub-clinical, which has shown to have a negative impact on some individuals, or clinical with symptoms ranging from excess saliva around the mouth to gross lesions in the oesophagus and oral cavity. This disease is known as trichomonosis. The lesions can grow and result in blocking the oesophagus, leading to starvation and death. Trichomonosis epidemics has had devasting impacts on other avian populations. It has recently been shown to a be a cause of death in both adult and nestling Turtle Doves however the impact on Turtle Dove populations has not been established.

Turtle Dove populations in the UK were screened for the presence of T. gallinae during the years 2012-2015. Another breeding population in France (2014) was screened in addition to over-wintering populations in Senegal (2014-2015) and Burkina Faso (2012).

Prevalence results revealed 100% infection for all populations, with the exception of UK 2013 (96%). There is no baseline data available for Trichomonas infection, so whether this high infection rate has always been the case or the result of an increase over a number of years is unknown.

The next step is investigating the genetic strain composition. Initial results have hinted that this varies between years with a virulent strain (responsible for a trichomonosis epidemic in UK finches) infecting more adult Turtle Doves in 2012 than in the following year. The breeding season of 2012 was also a bad year in terms of observed cases of trichomonosis in Turtle Doves.

Another aim is to establish risk factors of infection with particular strains. Screening samples of the wild bird population has taken place in addition to assessing the presence and persistence of T. gallinae in shared food resources in order to identify potential transmission routes.

The impact of infection is also being investigated with data collected from radio tracking to inform of home ranges, foraging preferences and breeding productivity.