Louse flies, or flat flies, are a parasitic group that live on birds and suck their blood. They are known to transmit diseases such as avian malaria. In new research, Denise Wawman recruited licensed bird ringers to collect louse flies, acting as citizen scientists.
Over 170 ringing groups and individual bird ringers collected over 3500 flies which left the birds that they were ringing. Denise then identified the flies under a microscope and plotted their current ranges, before comparing them with the ranges that were published in the early 1960s by Dennis Hill.
Several species of louse flies that are known to have diverse bird hosts have shifted their ranges over 300km (about 200 miles) north since the early 1960s – with one colonising Wales and Ireland since the last study. Another species, usually found on swallows, has recently established itself throughout England and Wales, despite not being found in the UK in the 1980s. An increasing number of parasites that are capable of transmitting diseases may increase the risk of some diseases in birds.
Denise was expecting species to have shifted their ranges due to climate change, but was surprised at how far north they had moved. She said:
“Most species have shifted their ranges more slowly, for example, dragonflies have, on average, moved northwards by about 74km in 25 years. As parasite species shift their ranges, species that may not have met before are more likely to do so, potentially bringing diseases to new hosts.”
It is possible that these flies may be carrying diseases, and that these could be transmitted between bird species. If other parasites, such as ticks, are also present on the same bird, they might also catch a disease, with the risk that some infections could be passed to other species that they bite. Denise added:
“These are large flies for the size of their avian hosts – it’s equivalent to a human having a fly the size of a shore crab on their face. Even Miriam Rothschild and Theresa Clay, who studied fleas, thought that these flies were “particularly repellent insects”. Bird ringers were very happy to be rid of them as they have a tendency to leave the birds and crawl around in their hair!”
Denise plans to investigate which species of these flies are present on which birds, and to look at the disease-causing organisms which can be found within them, while continuing to monitor the ranges of species present in the region.
To read more about this research, published in Medical and Veterinary Entomology, visit: https://doi.org/10.1111/mve.12795
