Ecology 6th Edition by Charles Krebs

Exercise 10

By treating house martins (Delichon urbica) with antimalarial drugs, Marzal et al. (2005) were able to show that the malarial blood parasites in Spain reduced production of young birds by about 40%. In Denmark house martins do not carry this malarial parasite. Would you expect the population density of these birds to be higher in Denmark? Why or why not?