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Hanapēpē Heights, HI, United States

Glad A.,University of Hawaii at Manoa | Crampton L.H.,Kauai Forest Bird Recovery Project
Journal of Vector Ecology | Year: 2015

Avian malaria is among the most important threats to native Hawaiian forest birds. It is caused by the parasite Plasmodium relictum and is transmitted by the introduced mosquito vector Culex quinquefasciatus. Temperature increases and precipitation declines due to climate change over the last decade may be responsible for the observed recent expansion in the range and prevalence of avian malaria on the Alakai Plateau, Kauai Island. To examine the hypothesis that conditions are now favorable for transmission of malaria on the Plateau, mosquitoes were sampled with CO2 and Reiter oviposition traps at three sites (Kawaikoi, Halepa'akai, and Koke'e) on several occasions between October, 2013 and April, 2014. P. relictum infection was assessed by PCR or dissection under a microscope. We also surveyed mosquito larvae along Halepa'akai and Kawaikoi streams. We observed that Cx. quinquefasciatus is well established on the Alakai Plateau, as mosquitoes were caught on all field trips, except in April at Halepa'akai, and larvae were found throughout the year. We observed differences in adult abundance among sites and microhabitats (stream vs ridge lines). © 2015 The Society for Vector Ecology.

Atkinson C.T.,U.S. Geological Survey | Utzurrum R.B.,University of Hawaii at Hilo | Lapointe D.A.,U.S. Geological Survey | Camp R.J.,University of Hawaii at Hilo | And 4 more authors.
Global Change Biology | Year: 2014

Transmission of avian malaria in the Hawaiian Islands varies across altitudinal gradients and is greatest at elevations below 1500 m where both temperature and moisture are favorable for the sole mosquito vector, Culex quinquefasciatus, and extrinsic sporogonic development of the parasite, Plasmodium relictum. Potential consequences of global warming on this system have been recognized for over a decade with concerns that increases in mean temperatures could lead to expansion of malaria into habitats where cool temperatures currently limit transmission to highly susceptible endemic forest birds. Recent declines in two endangered species on the island of Kaua'i, the 'Akikiki (Oreomystis bairdi) and 'Akeke'e (Loxops caeruleirostris), and retreat of more common native honeycreepers to the last remaining high elevation habitat on the Alaka'i Plateau suggest that predicted changes in disease transmission may be occurring. We compared prevalence of malarial infections in forest birds that were sampled at three locations on the Plateau during 1994-1997 and again during 2007-2013, and also evaluated changes in the occurrence of mosquito larvae in available aquatic habitats during the same time periods. Prevalence of infection increased significantly at the lower (1100 m, 10.3% to 28.2%), middle (1250 m, 8.4% to 12.2%), and upper ends of the Plateau (1350 m, 2.0% to 19.3%). A concurrent increase in detections of Culex larvae in aquatic habitats associated with stream margins indicates that populations of the vector are also increasing. These increases are at least in part due to local transmission because overall prevalence in Kaua'i 'Elepaio (Chasiempis sclateri), a sedentary native species, has increased from 17.2% to 27.0%. Increasing mean air temperatures, declining precipitation, and changes in streamflow that have taken place over the past 20 years are creating environmental conditions throughout major portions of the Alaka'i Plateau that support increased transmission of avian malaria. © 2014 John Wiley & Sons Ltd.

Behnke L.A.H.,Colorado State University | Pejchar L.,Colorado State University | Crampton L.H.,Kauai Forest Bird Recovery Project
Condor | Year: 2015

Limited resources for biodiversity conservation demand strategic science-based recovery efforts, particularly on islands, which are global hotspots of both endemism and extinction. The Akikiki (Oreomystis bairdi) and the Akekee (Loxops caeruleirostris) are critically endangered honeycreepers endemic to the Hawaiian island of Kauai. Recent declines and range contraction spurred investigation of the habitat characteristics influencing range-wide occupancyof these species. We surveyed Akikiki and Akekee and habitat covariates within 5 study areas on the Alakai Plateau of Kauai along a gradient of forest conditions. Occupancy rates for both species increased from west to east along theplateau (Akikiki: ψ=0.02 6 0.07 to 0.55 6 0.21; Akekee: ψ=0.03 6 0.10 to 0.53 6 0.33), but were low throughout the ranges of both species. Canopy height was positively correlated with occupancy for both species, which suggests thedamage done by hurricanes in 1982 and 1992 may be one factor restricting these birds to the most intact forest remaining. Vegetation surveys revealed several key differences in forest composition and structure between areas, indicative of broader changes occurring across the plateau. Invasive plants such as Himalayan ginger (Hedychium gardnerianum) were dominant in the western portion of the plateau, where there was a corresponding decline innative plant cover. Conversely, ground disturbance by feral ungulates was higher in more eastern native-dominated areas. These results highlight the need to protect habitat in the regions where Akikiki and Akekee occupancy ishighest, and restore habitat in other parts of their range. These actions should occur in concert with the mitigation of other known threats to Hawaiian honeycreepers such as avian disease. Without significant investment to address thesethreats and protect suitable habitat for these species, it is unclear how long these birds will persist. © 2016 Cooper Ornithological Society.

Hammond R.L.,Northern Arizona University | Crampton L.H.,Kauai Forest Bird Recovery Project | Foster J.T.,Northern Arizona University | Foster J.T.,University of New Hampshire
Condor | Year: 2015

Two forest bird species endemic to the island of Kauai in the Hawaiian Archipelago were listed under the U.S. Endangered Species Act in 2010 due to recent population declines. This research represents the first comprehensive breeding biology study of both species, the 'Akikiki or Kauai Creeper (Oreomystis bairdi) and 'Akeke'e or Akekee (Loxops caeruleirostris). The 2-year study was initiated in 2012 to determine if low nesting success may be a cause of their population declines. We monitored 20 'Akikiki and 8 'Akeke'e nests to assess basic nesting biology parameters (e.g., brood size; nest height; length of construction, incubation, and nestling periods) and to derive estimates of nesting success and investigate causes of failure. In general, 'Akikiki and 'Akeke'e breeding biology was similar to other insectivorous Hawaiian honeycreepers. Mean nest height for 'Akikiki and 'Akeke'e was high (9.2 ± 2.3 m SD and 11.1 ± 2.3 m SD, respectively) compared to most Kauai forest birds. Nesting success, calculated using program MARK, was 0.77 ± 0.12 SE for 'Akikiki and 0.71 ± 0.17 SE for 'Akeke'e. Three 'Akikiki and 2 'Akeke'e nests failed. One 'Akikiki nest failed due to nest predation and the other 2 to unknown causes. One 'Akeke'e nest failed due to poor nest attendance and the other to hatching failure. Nest sample sizes were small and should be considered with caution; however, these results suggest that low nesting success may not be a primary cause of decline in these species. Future research on both species should assess post-fledging, juvenile, and adult survival as potential causes of their populations' declines. Determining which demographic parameters currently have the largest negative impact on these populations is imperative for guiding effective management actions to conserve these species. © 2015 American Ornithologists' Union.

Hammond R.L.,Northern Arizona University | Hammond R.L.,Prairie Research Institute | Crampton L.H.,Kauai Forest Bird Recovery Project | Foster J.T.,Northern Arizona University | Foster J.T.,University of New Hampshire
Journal of Avian Biology | Year: 2016

Forests of the Hawaiian archipelago are a global hotspot for conserving avian diversity and contain among the world's most imperiled species. Demographic studies are necessary to determine primary causes of Hawaiian forest bird population declines. We conducted research on the nesting success of multiple bird families on the island of Kaua'i, allowing us to investigate the importance of factors related to breeding biology on forest bird declines at a community scale. Our study included two Hawaiian honeycreepers, 'anianiau Magumma parva and 'apapane Himatione sanguinea, a native monarch flycatcher, Kaua'i 'elepaio Chasiempis sclateri, and one introduced species, Japanese white-eye Zosterops japonicus. Data from 123 nests showed that nesting success ± SE, estimated using program MARK, was low for 'apapane (0.23 ± 0.10), but did not vary substantially among our other study species ('anianiau = 0.56 ± 0.09, Kaua'i 'elepaio = 0.63 ± 0.08, Japanese white-eye = 0.52 ± 0.11). Causes of nest loss for 51 nest failures included nest predation (43%), unknown (25%), empty after termination with no signs of nest predation (e.g. eggshell or chick remains in nest, disheveled nest) (24%), and abandoned clutch or brood (4% each). Kaua'i 'elepaio suffered more than twice as many nest losses to predation compared to our other study species, but also had the highest nesting success; and, 'apapane suffered least to nest predation, but had the lowest nesting success. Further, rates of nesting success derived in our study were relatively high compared to multi-species studies in mainland tropics. Therefore, although nest predation accounted for the greatest proportion of nest failures, it may not be a cause of forest bird population declines in our system. We suggest that future demographic studies focus on post-fledgling, juvenile, and adult survival, in addition to the importance of double-brooding and renesting attempts on annual reproductive success. Journal of Avian Biology © 2016 Nordic Society Oikos.

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