Avian malaria-mediated population decline of a widespread iconic bird species

Abstract

Parasites have the capacity to affect animal populations by modifying host survival, and it is increasingly recognized that infectious disease can negatively impact biodiversity. Populations of the house sparrow ( Passer domesticus ) have declined in many European towns and cities, but the causes of these declines remain unclear. We investigated associations between parasite infection and house sparrow demography across suburban London where sparrow abundance has declined by 71% since 1995. Plasmodium relictum infection was found at higher prevalences (averaging 74%) in suburban London house sparrows than previously recorded in any wild bird population in Northern Europe. Survival rates of juvenile and adult sparrows and population growth rate were negatively related to Plasmodium relictum infection intensity. Other parasites were much less prevalent and exhibited no relationship with sparrow survival and no negative relationship with population growth. Low rates of co-infection suggested sparrows were not immunocompromised. Our findings indicate that P. relictum infection may be influencing house sparrow population dynamics in suburban areas. The demographic sensitivity of the house sparrow to P. relictum infection in London might reflect a recent increase in exposure to this parasite.

Host phylogeny matters: Examining sources of variation in infection risk by blood parasites across a tropical montane bird community in India

“…These parasites are transmitted by arthropod vectors, with Plasmodium being transmitted by culicid mosquitoes, and Haemoproteus by ceratopogonid biting midges and hippoboscid louse flies [ 21 , 23 ]. Avian haemosporidians can impose strong selective pressures on bird hosts as they are known to reduce longevity [ 24 ], host fitness [ 25 , 26 ], individual host condition [ 27 ] and have led to severe population declines [ 28 – 31 ]. Previous research has revealed that avian haemosporidian parasites vary widely in their host range, with Plasmodium lineages often being generalists infecting a broad range of host species and Haemoproteus lineages often being specialists infecting one or few closely related host species [ 32 – 34 ] but this pattern is not universal [ 35 , 36 ].…”

Host Phylogeny Matters: Examining Sources of Variation in Infection Risk by Blood Parasites Across a Tropical Montane Bird Community in India

“…These parasites are transmitted by arthropod vectors, with Plasmodium being transmitted by Culicid mosquitoes, and Haemoproteus by Ceratopogonid biting midges and Hippoboscid louse ies [17,19]. Avian haemosporidians can impose strong selective pressures on bird hosts as they are known to reduce longevity [20], host tness [21,22], individual host condition [23] and have led to severe population declines [24][25][26][27]. Previous research has revealed that avian haemosporidian parasites vary widely in their host range, with Plasmodium lineages often being generalists infecting a broad range of host species and Haemoproteus lineages often being specialists infecting one or few closely related host species [28,29].…”

Artificial light at night amplifies seasonal relapse of haemosporidian parasites in a widespread songbird

“…For haemosporidian parasites, fitness costs for birds can be highly variable [25]. In some cases, haemosporidians have caused dramatic population declines in hosts such as some Hawaiian honeycreepers (e.g., Vestiaria coccinea) and possibly house sparrows (Passer domesticus) in Europe [59,60]. Relapse of chronic infections under ALAN in anthropogenic habitats could accordingly either facilitate infection-related population declines in less tolerant avian hosts or increase parasitemia in tolerant species that instead serve as sources of infection for generalist vectors, thereby increasing transmission in the local avian community.…”