Blood parasites in Galápagos blue-footed boobies appear not to affect bird’s health
Prevalence of Haemoproteus sp. in Galápagos blue-footed boobies: effects on health and reproduction by Dr Larisa Lee-Cruz et al. is the Parasitology Open Paper of the Month for March.
“Blue-footed boobies are likable, funny-looking seabirds. With their bright plumage and flashy blue feet, they are among the favourites of the Galápagos Islands fauna. They are widespread in the archipelago and can be easily seen. However, when we visited the islands in 2007 we saw a lot less blue-footed boobies than expected; many of them were not even breeding. Scattered information on population numbers of these birds and researchers that we contacted who visit regularly the islands, all gave hints that the birds were not as common as a few decades ago. At the same time, several studies were showing concern over the impact of introduced diseases on the native fauna, and blood parasites had already been found in some avian species in the archipelago, including seabirds. Could such parasites be responsible of poor breeding or survival in the Galápagos blue-footed boobies? Were these parasites even present in this species?
As in humans, infection in birds can also have negative consequences. For example, an infected male might not be able to attract a female, an infected female might produce low quality eggs, or infected parents may provide poor care to their offspring. Thus, the presence of blood parasites in wild populations is not a trivial thing. Blood parasites, such as Haemoproteus and Plasmodium, the two types on which we focused, are transmitted by ticks, flies and mosquitoes, all of which are found in the Galápagos feeding on blue-footed boobies. In fact ticks and flies are common ectoparasites of these birds.
Although none of the birds that we sampled tested positive for Plasmodium, a high proportion, sometimes over 50%, of blue-footed boobies tested positive for Haemoproteus on the six different islands on which we sampled adults. On two of these islands, on which we also sampled chicks, these tested positive as well. However, the presence of this parasite did not seem to affect the physiological condition of the birds, nor their reproduction, as breeding success was similar between parasitized and non-parasitized birds. Chicks did not seem to be affected by the parasite either in terms of growth or survival. It is possible that the parasite is present in the blood of the birds but in small amount, and therefore it has no impact in practical terms. However, the amount of parasites in the blood can vary in time depending on factors that can promote or suppress the reproduction of the parasite within each individual. A regular and repeated sampling of the birds could aid in establishing if there is variation in the amount of parasites circulating in their blood, what factors could be associated with this variation, if found, and if it affects the birds in some detrimental way that could be associated with the population decline.”
Prevalence of Haemoproteus sp. in Galápagos blue-footed boobies: effects on health and reproduction is an Open Access article and is therefore freely available to all.
Photo credit: Arnaud Bataille