Temporal Variation in Bird and Resource Abundance Across an Elevational Gradient in Hawaii

Hart, Patrick J.; Woodworth, Bethany L.; Camp, Richard J.; Turner, Kathryn; McClure, Katherine M.; Goodall, Katherine; Henneman, Carlene; Spiegel, Caleb S.; LeBrun, Jaymi J.; Tweed, Erik J.; Samuel, Michael D.

doi:10.1525/auk.2011.10031

Cited by 32 publications

(57 citation statements)

References 30 publications

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“…Our results show that malaria infection is lowest in highelevation forests where climate is less favourable for mosquito populations and malaria parasite development (Ahumada et al 2004, Samuel et al 2011. As a result, these high-elevation forests currently provide a relatively disease-free refuge v www.esajournals.org for susceptible honeycreepers (Ahumada et al 2004, Atkinson andLaPointe 2009b).…”

Section: Discussionmentioning

confidence: 72%

“…We also used fp to calculate an index of the relative contribution of native species (in pairs) to infecting susceptible mosquitoes IM j,k ¼ fp j,k 3 IB j /IB k , where IB is the number of infected birds for each species calculated as the proportion of infectious birds 3 P. Our approach assumes that avian species have equal likelihood of becoming infected by mosquitoes, which is supported by experimental studies showing 98% infection of all three species from a single bite by an infectious mosquito (Samuel et al 2011: Appendix B; C. T. Atkinson, unpublished data). Both equations were solved using Bayesian analyses which included the species and elevation specific parameters and variances on the right-hand-side of the equations.…”

Section: Vector-host Interactionmentioning

confidence: 89%

“…There were broad similarities in substrate age, rainfall, and vegetation for sites within the same altitudinal zone. Intensity of disease transmission varies across this landscape primarily driven by seasonal and altitudinal differences in both temperature and rainfall that affect abundance of Culex quinquefasciatus and the intrinsic incubation of P. relictum (Ahumada et al 2004, Ahumada et al 2009, Samuel et al 2011. Mean monthly temperatures range from 248C at low elevation to approximately 138C at high elevation.…”

Section: Study Species and Areamentioning

confidence: 99%

“…of AD captured in winter). We enhanced model parameter estimates using Bayesian priors for the estimated malaria fatality rates (m) for the three native species based on experimental laboratory studies from high and low elevation Amakihi, Apapane, and Iiwi (Atkinson et al 1995, Yorinks and Atkinson 2000, Samuel et al 2011, Atkinson et al 2013). We used a beta distribution (b(survivors þ 1, fatalities þ 1)) to estimate priors based on the number of survivors and fatalities in laboratory studies for each species: Iiwi b(2, 9), Apapane b(6, 4), Amakihi b(13, 19), and lowelevation Amakihi b(11, 2).…”

Section: Epizootiological Modelingmentioning

confidence: 99%

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Avian malaria in Hawaiian forest birds: infection and population impacts across species and elevations

et al. 2015

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Abstract. Wildlife diseases can present significant threats to ecological systems and biological diversity, as well as domestic animal and human health. However, determining the dynamics of wildlife diseases and understanding the impact on host populations is a significant challenge. In Hawai'i, there is ample circumstantial evidence that introduced avian malaria (Plasmodium relictum) has played an important role in the decline and extinction of many native forest birds. However, few studies have attempted to estimate disease transmission and mortality, survival, and individual species impacts in this distinctive ecosystem. We combined multi-state capture-recapture (longitudinal) models with cumulative age-prevalence (crosssectional) models to evaluate these patterns in Apapane, Hawai'i Amakihi, and Iiwi in low-, mid-, and high-elevation forests on the island of Hawai'i based on four longitudinal studies of 3-7 years in length. We found species-specific patterns of malaria prevalence, transmission, and mortality rates that varied among elevations, likely in response to ecological factors that drive mosquito abundance. Malaria infection was highest at low elevations, moderate at mid elevations, and limited in high-elevation forests. Infection rates were highest for Iiwi and Apapane, likely contributing to the absence of these species in low-elevation forests. Adult malaria fatality rates were highest for Iiwi, intermediate for Amakihi at mid and high elevations, and lower for Apapane; low-elevation Amakihi had the lowest malaria fatality, providing strong evidence of malaria tolerance in this low-elevation population. Our study indicates that hatch-year birds may have greater malaria infection and/or fatality rates than adults. Our study also found that mosquitoes prefer feeding on Amakihi rather than Apapane, but Apapane are likely a more important reservoir for malaria transmission to mosquitoes. Our approach, based on host abundance and infection rates, may be an effective alternative to mosquito blood meal analysis for determining vector-host contacts when mosquito densities are low and collection of blood-fed mosquitoes is impractical. Our study supports the hypothesis that avian malaria has been a primary factor influencing the elevational distribution and abundance of these three species, and likely limits other native Hawaiian species that are susceptible to malaria.

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Section: Discussionmentioning

confidence: 72%

Section: Vector-host Interactionmentioning

confidence: 89%

Section: Study Species and Areamentioning

confidence: 99%

Section: Epizootiological Modelingmentioning

confidence: 99%

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Avian malaria in Hawaiian forest birds: infection and population impacts across species and elevations

et al. 2015

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“…Approximately 41% of bird families have mixed diets that include fruit to varying degrees (Jordano, 1992), which suggests that tracking food resources other than fruit can have implications that reach beyond the distribution and demographics of the consumer, since tracking a non-fruit resource may influence consumption of fruit in the area. For instance, 'ōhi'a (Metrosideros polymorpha) flowers significantly predicted the abundance of Japanese whiteeyes (Zosterops japonicus) in Hawai'i (Hart et al, 2011), where it has become an important frugivore (Foster and Robinson, 2007). However, these cross-resource type interactions have limited current data, therefore, we will focus on fruit tracking.…”

Section: Resource Tracking By Vertebratesmentioning

confidence: 99%

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

2017

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Mutualistic interactions between species are crucial for the maintenance and functioning of the community. Current research has shown the importance of not only understanding the structure of these mutualistic interaction networks but also their temporal dynamics. Temporal changes in species abundance, such as those caused by vertebrate resource tracking, may create temporal variability in a network though neighborhood effects and influence the directedness of dispersal. While much research has been done on resource tracking, neighborhood effects, and directed dispersal individually, little research has been done into their interrelationships and, therefore, theory of how resource tracking can influence frugivory and seed dispersal networks remains poorly developed. We use the available literature to show the prevalence of resource tracking by vertebrate frugivores and hypothesize how, through neighborhood effects, resource tracking may influence short-term variation in network properties. We then discuss how resource tracking can influence long-term network properties by altering the dispersal of plant species. Lastly, we use this information to hypothesize how the introductions of new species into a community may alter the influence of resource tracking on frugivory and seed dispersal. While trait matching and links that are not possible between species in a community (i.e., forbidden links) play a large role in determining the structure of a network, temporal change in the abundance of species due to resource tracking may also affect the properties of networks. By increasing our understanding of the role resource tracking has in the temporal variability of frugivory and seed dispersal networks, we can better determine the full extent of species interactions and provide valuable information for the conservation of ecological communities.

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When Worlds Collide: Challenges and Opportunities for Conservation of Biodiversity in the Hawaiian Islands

Atkinson

Pratt

Banko

et al. 2013

Conservation Biology

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Temporal Variation in Bird and Resource Abundance Across an Elevational Gradient in Hawaii

Cited by 32 publications

References 30 publications

Avian malaria in Hawaiian forest birds: infection and population impacts across species and elevations

Avian malaria in Hawaiian forest birds: infection and population impacts across species and elevations

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

When Worlds Collide: Challenges and Opportunities for Conservation of Biodiversity in the Hawaiian Islands

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