Increase in Avian Malaria at Upper Elevation in Hawai‘i

Abstract Hawaiian honeycreepers (Aves: Drepanidinae) evolved in the absence of mosquito-borne diseases such as avian malaria (Plasmodium spp.). Malaria has been largely responsible for the recent wave of extinctions and endangerment among Hawaiian forest birds, which began by the 1920s. Most honeycreepers, especially endangered species, now persist only in forests above 1500 m elevation, where cool temperatures prevent effective malaria development in mosquitoes. We report here that prevalence of malaria in Hawaiian forest birds at 1900 m on the island of Hawai‘i has more than doubled over a decade. This increase was associated with breeding of mosquitoes and warmer summertime air temperatures. We also report direct evidence of tolerance to malaria, and a possible cost of tolerance, in wild native birds. Tolerance is adding to a reservoir of malaria at upper elevations even while vectors are rare and air temperatures are too low for complete development of the parasite in the vector. The data provide a glimpse of how malaria is becoming an emergent infectious disease at upper elevations.

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Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

Pacific Conservation Biology ◽

10.1071/pc100181 ◽

2010 ◽

Vol 16 (3) ◽

pp. 181 ◽

Cited By ~ 1

Author(s):

Katherine Tucker-Mohl ◽

Patrick Hart ◽

Carter T. Atkinson

Keyword(s):

Avian Malaria ◽

Native Hawaiian ◽

Forest Birds ◽

Dry Forest ◽

Natural Resistance ◽

Native Forest ◽

Dry Forests ◽

Plasmodium Relictum ◽

Hawaiian Forest Birds ◽

Native Birds

Hawaii?s native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural ?refuges? from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

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Ecology and diagnosis of introduced avian malaria in Hawaiian forest birds

Fact Sheet ◽

10.3133/fs20053151 ◽

2005 ◽

Cited By ~ 2

Author(s):

Carter T. Atkinson

Keyword(s):

Avian Malaria ◽

Forest Birds ◽

Hawaiian Forest Birds

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Mitigating Future Avian Malaria Threats to Hawaiian Forest Birds from Climate Change

PLoS ONE ◽

10.1371/journal.pone.0168880 ◽

2017 ◽

Vol 12 (1) ◽

pp. e0168880 ◽

Cited By ~ 12

Author(s):

Wei Liao ◽

Carter T. Atkinson ◽

Dennis A. LaPointe ◽

Michael D. Samuel

Keyword(s):

Climate Change ◽

Avian Malaria ◽

Forest Birds ◽

Hawaiian Forest Birds

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Epizootiology and Effect of Avian Pox on Hawaiian Forest Birds

The Auk ◽

10.1093/auk/119.4.929 ◽

2002 ◽

Vol 119 (4) ◽

pp. 929-942 ◽

Cited By ~ 10

Author(s):

Charles van Riper ◽

Sandra G. van Riper ◽

Wallace R. Hansen

Keyword(s):

Introduced Species ◽

Forest Birds ◽

Native Forest ◽

Wet Season ◽

Altitudinal Distribution ◽

Negative Effect ◽

Activity Cycles ◽

Avian Pox ◽

Hawaiian Forest Birds ◽

Native Birds

Abstract We determined prevalence and altitudinal distribution of forest birds infected with avian pox at 16 locations on Hawaii, from sea level to tree line in mesic and xeric habitats, during 1977–1980. Isolates from lesions were cultured in the laboratory for positive identification of Poxvirus avium. Infected birds from the wild were brought into the laboratory to assess differences in the course of infection in native versus introduced species. We also documented distributions and activity cycles of potential avian pox vectors.>Native forest birds were (1) more susceptible to avian pox infection than were introduced species, (2) most likely to be infected during the wet season, and (3) found to have a higher prevalence in mesic when compared to xeric forests. Avian pox occurred in forest birds at all elevations, but highest levels were in the mid-elevational ranges (∼1,200 m) where vectors and native birds had the greatest overlap. Temporal and elevational differences in prevalence were apparent throughout the annual cycle. Avian pox probably did not reach epizootic proportions on Hawaii until after introduction of the mosquito and domestic birds in the early 1800s, and since then has had a negative effect on the population dynamics of native forest birds. Today, this introduced disease is an important factor that should be considered in future conservation efforts that are directed at the recovery of native forest birds in Hawaii.

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Avian malaria Plasmodium relictum in native Hawaiian forest birds: epizootiology and demographic impacts on ‵apapane Himatione sanguinea

Journal of Avian Biology ◽

10.1111/j.1600-048x.2009.04915.x ◽

2010 ◽

Vol 41 (4) ◽

pp. 357-366 ◽

Cited By ~ 75

Author(s):

Carter T. Atkinson ◽

Michael D. Samuel

Keyword(s):

Avian Malaria ◽

Native Hawaiian ◽

Forest Birds ◽

Plasmodium Relictum ◽

Hawaiian Forest Birds

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Wildlife disease and conservation in Hawaii: Pathogenicity of avian malaria (Plasmodium relictum) in experimentally infected Iiwi (Vestiaria coccinea)

Parasitology ◽

10.1017/s003118200007582x ◽

1995 ◽

Vol 111 (S1) ◽

pp. S59-S69 ◽

Cited By ~ 187

Author(s):

C. T. Atkinson ◽

K. L. Woods ◽

R. J. Dusek ◽

L. S. Sileo ◽

W. M. Iko

Keyword(s):

Body Weight ◽

Food Consumption ◽

Native Species ◽

Avian Malaria ◽

Low Dose ◽

Native Hawaiian ◽

Forest Birds ◽

High Dose ◽

Plasmodium Relictum ◽

Hawaiian Forest Birds

SUMMARYNative Hawaiian forest birds are facing a major extinction crisis with more than 75% of species recorded in historical times either extinct or endangered. Reasons for this catastrophe include habitat destruction, competition with non-native species, and introduction of predators and avian diseases. We tested susceptibility of Iiwi (Vestiaria coccinea), a declining native species, and Nutmeg Mannikins (Lonchura punctulata), a common non-native species, to an isolate ofPlasmodium relictumfrom the island of Hawaii. Food consumption, weight, and parasitaemia were monitored in juvenile Iiwi that were infected by either single (low-dose) or multiple (high-dose) mosquito bites. Mortality in both groups was significantly higher than in uninfected controls, reaching 100% of high-dose birds and 90% of low-dose birds. Significant declines in food consumption and a corresponding loss of body weight occurred in malaria-infected birds. Both sex and body weight had significant effects on survival time, with males more susceptible than females and birds with low initial weights more susceptible than those with higher initial weights. Gross and microscopic lesions in malaria fatalities included massive enlargement of the spleen and liver, hyperplasia of the reticuloendothelial system with extensive deposition of malarial pigment, and overwhelming anaemia in which over 30% of the circulating erythrocytes were parasitized. Nutmeg Mannikins, by contrast, were completely refractory to infection. Our findings support previous studies documenting high susceptibility of native Hawaiian forest birds to avian malaria. This disease continues to threaten remaining high elevation populations of endangered native birds.

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