Honolulu, HI, United States
Honolulu, HI, United States

Time filter

Source Type

Reed J.M.,Tufts University | Desrochers D.W.,Dalton State College | Vanderwerf E.A.,Pacific Rim Conservation | Scott J.M.,The College of Idaho
BioScience | Year: 2012

One-third of the bird species listed under the US Endangered Species Act are endemic to Hawaii. One requirement of delisting a species is the elimination or abatement of threats to that species. More than 95% of Hawaii's threatened and endangered species face multiple threats that cannot be eliminated (e.g., alien mammalian predators, invasive alien plants that alter habitat structure, disease). However, because we can manage many of the threats at scales at which the achievement of recovery goals is possible, these species could be delisted if conservation partners committed to the implementation of stewardship agreements to maintain viable populations following those populations' delistings. © 2012 by American Institute of Biological Sciences. All rights reserved. Request permission to photocopy or reproduce article content at the University of California Press's Rights and Permissions Web site at .


Animals often exhibit predictable geographic variation in morphology, and such ecogeographic patterns reflect local adaptation to varying environmental conditions. The most common of these patterns are termed Bergmann's, Allen's, and Gloger's rules. I studied morphological variation in the Hawaii Elepaio (Chasiempis sandwichensis) and the Oahu Elepaio (C. ibidis), forest birds endemic to the Hawaiian Islands. I measured body size and plumage color of 223 live elepaios captured at 36 sites on Hawaii and 132 live elepaios captured at 23 sites on Oahu, and I examined 132 museum specimens from an additional 22 locations on Hawaii. I used multiple regressions to examine relationships of elepaio body size and plumage color to elevation and annual rainfall on each island. Size of Hawaii Elepaios varied among sites and was related to elevation and rainfall. Wing chord, tail length, and body mass had positive relationships with elevation, as predicted by Bergmann's rule. Proportional bill length and proportional tarsus length were inversely related to elevation, as predicted by Allen's rule. In Hawaii Elepaios, 17 of 20 plumage color variables were related to rainfall. Elepaios in wetter areas were more heavily pigmented and had fewer and smaller white markings, as predicted by Gloger's rule. Plumage color of Oahu Elepaios showed similar but weaker patterns and only two of 20 plumage characters were related to rainfall. All body-size and plumage-color measurements had smoothly clinal distributions, with no large gaps with respect to elevation or rainfall. Putative subspecies of the Hawaii Elepaio differed in mean value of several plumage characters, but there was overlap in plumage color among subspecies and variation within them, and none of the three subspecies was diagnosable from both other subspecies by any plumage character using the 75% rule. Elepaios differed morphologically among sites only a few kilometers apart because of their sedentary behavior and the steep gradients in temperature and elevation and limited climatic variation of the tropical environment of the Hawaiian Islands. Morphological variation in elepaios is smoothly clinal because there are few dispersal barriers and elepaios inhabit areas with a range of climates and vegetation. Although my results did not support the designation of subspecies within the Hawaii Elepaio, morphological and underlying genetic variation is important, and conservation of elepaios with varying phenotypes would preserve evolutionary potential and ability to adapt to climate change. © The American Ornithologists' Union, 2011.


Van Der Werf E.A.,Pacific Rim Conservation | Young L.C.,Pacific Rim Conservation
Auk | Year: 2011

Accurate estimates of demographic rates are fundamental to understanding population dynamics and can provide insights into the ecology and conservation of a species. We used multistate mark-recapture models to estimate apparent annual survival, encounter probability, and life-stage transitions in Laysan Albatrosses (Phoebastria immutabilis) at Kaena Point, Hawaii, from 2003 to 2010. Four-state models of prebreeders, breeders, failed breeders, and skipped breeders overestimated survival by 1-3% and underestimated skipped breeding by 5-6%, but five-state models that included a state for unobserved skipped breeders performed better. Survival did not vary among years and was highest in prebreeders (mean ± SE = 0.996 ± 0.010) and lower in successful breeders (0.932 ± 0.023) than in failed breeders (0.963 ± 0.018), suggesting a cost to reproduction. Survival was similar in males and females among prebreeders, breeders, and failed breeders, but survival of males was lower among skipped breeders. Encounter probability was related to monitoring effort; more frequent visits and use of field-readable auxiliary bands and remote cameras resulted in higher encounter rates. With sufficient effort, all skipped breeders were observed at the colony even though they did not breed. Recruitment averaged 24% in females and 21% in males and varied among years. Breeding frequency averaged 0.807 ± 0.028 and varied among years. Successful breeders were more likely than failed breeders to skip the next breeding season. Estimates of all demographic rates except recruitment were similar to estimates for Laysan Albatrosses from Midway in the 1960s despite differences in methodology. This information can help measure population dynamics, breeding population sizes, population trends, and efficacy of conservation actions. © The American Ornithologists' Union, 2011.


Vanderwerf E.A.,Pacific Rim Conservation | Young L.C.,Pacific Rim Conservation
Marine Ornithology | Year: 2014

The Red-tailed Tropicbird Phaethon rubricauda is a widespread but uncommon seabird that nests in the tropical Pacific and Indian oceans. The majority of the global population nests in the predator-free Northwestern Hawaiian Islands. In the Southeastern Hawaiian Islands, the species is restricted by non-native predators to steep coastal cliffs and small islets. We studied the breeding biology of Red-tailed Tropicbirds on O'ahu from 2005 to 2013, while we also controlled predatory non-native mongooses Herpestes auropunctatus and rats Rattus spp. with traps and poison bait stations to protect nests. Egg-laying peaked in March, hatching peaked in April and fledging peaked in July. The mean ± standard error incubation period was 44.2 ± 0.4 d (n = 155) and the mean fledging period was 82.3 ± 0.6 d (n = 127). The number of tropicbird chicks fledged increased steadily each year from seven to 26 in response to predator control, and reproductive success increased as predator control methods improved. Our results demonstrate that, with management, seabird colonies can thrive on islands inhabited by people and predators. More management is needed on high islands like O'ahu to enhance seabird populations and to help mitigate the projected impacts to seabirds of sea level rise associated with climate change.


Young L.C.,Pacific Rim Conservation | VanderWerf E.A.,Pacific Rim Conservation
Proceedings of the Royal Society B: Biological Sciences | Year: 2014

Same-sex pairing is widespread among animals but is difficult to explain in an evolutionary context because it does not result in reproduction, and thus same-sex behaviour often is viewed as maladaptive. Here, we compare survival, fecundity and transition probabilities of female Laysan albatross in different pair types, and we show how female-female pairing could be an adaptive alternative mating strategy, albeit one that resulted in lower fitness than male-female pairing. Females in same-sex pairs produced 80% fewer chicks, had lower survival and skipped breeding more often than those in male-female pairs. Females in same-sex pairs that raised a chick sometimes acquired a male mate in the following year, but females in failed same-sex pairs never did, suggesting that males exert sexual selection by assessing female quality and relegating low-quality females into same-sex pairs. Sexual selection by males in a monomorphic, non-ornamented species is rare and suggests that reconsideration is needed of the circumstances in which alternative reproductive behaviour evolves. Given the lack of males and obligate biparental care in this species, this research demonstrates how same-sex pairing was better than not breeding and highlights how it could be an adaptive strategy under certain demographic conditions. © 2013 The Author(s) Published by the Royal Society. All rights reserved.


Vanderwerf E.A.,Pacific Rim Conservation
Conservation Biology | Year: 2012

The majority of bird extinctions since 1800 have occurred on islands, and non-native predators have been the greatest threat to the persistence of island birds. Island endemic species often lack life-history traits and behaviors that reduce the probability of predation and they can become evolutionarily trapped if they are unable to adapt, but few studies have examined the ability of island species to respond to novel predators. The greatest threat to the persistence of the Oahu Elepaio (Chasiempis ibidis), an endangered Hawaiian forest bird, is nest predation by non-native black rats (Rattus rattus). I examined whether Oahu Elepaio nest placement has changed at the individual and population levels in response to rat predation by measuring nest height and determining whether each nest produced offspring from 1996 to 2011. Average height of Oahu Elepaio nests increased 50% over this 16-year period, from 7.9 m (SE 1.7) to 12.0 m (SE 1.1). There was no net change in height of sequential nests made by individual birds, which means individual elepaios have not learned to place nests higher. Nests ≤3 m off the ground produced offspring less often, and the proportion of such nests declined over time, which suggests that nest-building behavior has evolved through natural selection by predation. Nest success increased over time, which may increase the probability of long-term persistence of the species. Rat control may facilitate the evolution of nesting height by slowing the rate of population decline and providing time for this adaptive response to spread through the population. © 2012 Society for Conservation Biology.


Young L.C.,Pacific Rim Conservation
Proceedings. Biological sciences / The Royal Society | Year: 2014

Same-sex pairing is widespread among animals but is difficult to explain in an evolutionary context because it does not result in reproduction, and thus same-sex behaviour often is viewed as maladaptive. Here, we compare survival, fecundity and transition probabilities of female Laysan albatross in different pair types, and we show how female-female pairing could be an adaptive alternative mating strategy, albeit one that resulted in lower fitness than male-female pairing. Females in same-sex pairs produced 80% fewer chicks, had lower survival and skipped breeding more often than those in male-female pairs. Females in same-sex pairs that raised a chick sometimes acquired a male mate in the following year, but females in failed same-sex pairs never did, suggesting that males exert sexual selection by assessing female quality and relegating low-quality females into same-sex pairs. Sexual selection by males in a monomorphic, non-ornamented species is rare and suggests that reconsideration is needed of the circumstances in which alternative reproductive behaviour evolves. Given the lack of males and obligate biparental care in this species, this research demonstrates how same-sex pairing was better than not breeding and highlights how it could be an adaptive strategy under certain demographic conditions.


News Article | October 29, 2016
Site: www.sciencedaily.com

Understanding population dynamics is crucial for the conservation of long-lived species like albatrosses, but collecting data on albatrosses before they reach adulthood and begin to breed is challenging. A new study from The Condor: Ornithological Applications provides the first direct estimates of the population size and annual survival of young birds in Oahu's Laysan Albatross population, giving important new insights into the demographics of these "prebreeders." Husband-and-wife team Eric VanderWerf and Lindsay Young of Pacific Rim Conservation spent 14 years banding 477 Oahu albatrosses as chicks and monitoring what became of them. Contrary to the prevailing belief that young albatrosses remain at sea until they're ready to breed, VanderWerf and Young found that 2% of birds first returned to the colony as one-year-olds, 7% as two-year-olds, and 17% as three-year-olds. These early returners provided a rare window into the lives of young birds, allowing VanderWerf and Young to determine that prebreeders make up almost half of the Oahu population. Once they made it through their first year after fledging, the annual survival of these young birds was very high, estimated at about 97%. One threat to albatross populations is the mosquito-borne disease known as avian pox virus. "Although albatrosses and many other seabirds have strong immunity to avian pox virus, this disease has a negative long-term effect on their survival and chance of obtaining a mate," says VanderWerf. "As more albatrosses relocate to higher islands like Oahu in response to sea level rise, where mosquitoes are more prevalent, this disease, and perhaps others, will become a more important threat to the species, so we need to understand more about it and how to prevent its transmission." "This study provides novel insight into early life stage demographics of a long-lived seabird from the long-term study of a small and highly tractable colony. It is an excellent example of the value of long-term demographic studies for long-lived species such as albatrosses," according to Oregon State University's Robert Suryan, a seabird ecologist who was not involved in the study. "These results are highly relevant to the study, conservation, and management of long-lived species."


News Article | October 26, 2016
Site: phys.org

A new study provides a rare window the lives of young Laysan Albatrosses on Oahu. Credit: E. VanderWerf Understanding population dynamics is crucial for the conservation of long-lived species like albatrosses, but collecting data on albatrosses before they reach adulthood and begin to breed is challenging. A new study from The Condor: Ornithological Applications provides the first direct estimates of the population size and annual survival of young birds in Oahu's Laysan Albatross population, giving important new insights into the demographics of these "prebreeders." Husband-and-wife team Eric VanderWerf and Lindsay Young of Pacific Rim Conservation spent 14 years banding 477 Oahu albatrosses as chicks and monitoring what became of them. Contrary to the prevailing belief that young albatrosses remain at sea until they're ready to breed, VanderWerf and Young found that 2% of birds first returned to the colony as one-year-olds, 7% as two-year-olds, and 17% as three-year-olds. These early returners provided a rare window into the lives of young birds, allowing VanderWerf and Young to determine that prebreeders make up almost half of the Oahu population. Once they made it through their first year after fledging, the annual survival of these young birds was very high, estimated at about 97%. One threat to albatross populations is the mosquito-borne disease known as avian pox virus. "Although albatrosses and many other seabirds have strong immunity to avian pox virus, this disease has a negative long-term effect on their survival and chance of obtaining a mate," says VanderWerf. "As more albatrosses relocate to higher islands like Oahu in response to sea level rise, where mosquitoes are more prevalent, this disease, and perhaps others, will become a more important threat to the species, so we need to understand more about it and how to prevent its transmission." "This study provides novel insight into early life stage demographics of a long-lived seabird from the long-term study of a small and highly tractable colony. It is an excellent example of the value of long-term demographic studies for long-lived species such as albatrosses," according to Oregon State University's Robert Suryan, a seabird ecologist who was not involved in the study. "These results are highly relevant to the study, conservation, and management of long-lived species." Explore further: Oldest known seabird is back at Midway Atoll near Hawaii More information: "Juvenile survival, recruitment, population size, and effects of avian pox virus in Laysan Albatross (Phoebastria immutabilis) on Oahu, Hawaii, USA" October 26, 2016, americanornithologypubs.org/doi/full/10.1650/CONDOR-16-49.1


News Article | October 26, 2016
Site: www.eurekalert.org

Understanding population dynamics is crucial for the conservation of long-lived species like albatrosses, but collecting data on albatrosses before they reach adulthood and begin to breed is challenging. A new study from The Condor: Ornithological Applications provides the first direct estimates of the population size and annual survival of young birds in Oahu's Laysan Albatross population, giving important new insights into the demographics of these "prebreeders." Husband-and-wife team Eric VanderWerf and Lindsay Young of Pacific Rim Conservation spent 14 years banding 477 Oahu albatrosses as chicks and monitoring what became of them. Contrary to the prevailing belief that young albatrosses remain at sea until they're ready to breed, VanderWerf and Young found that 2% of birds first returned to the colony as one-year-olds, 7% as two-year-olds, and 17% as three-year-olds. These early returners provided a rare window into the lives of young birds, allowing VanderWerf and Young to determine that prebreeders make up almost half of the Oahu population. Once they made it through their first year after fledging, the annual survival of these young birds was very high, estimated at about 97%. One threat to albatross populations is the mosquito-borne disease known as avian pox virus. "Although albatrosses and many other seabirds have strong immunity to avian pox virus, this disease has a negative long-term effect on their survival and chance of obtaining a mate," says VanderWerf. "As more albatrosses relocate to higher islands like Oahu in response to sea level rise, where mosquitoes are more prevalent, this disease, and perhaps others, will become a more important threat to the species, so we need to understand more about it and how to prevent its transmission." "This study provides novel insight into early life stage demographics of a long-lived seabird from the long-term study of a small and highly tractable colony. It is an excellent example of the value of long-term demographic studies for long-lived species such as albatrosses," according to Oregon State University's Robert Suryan, a seabird ecologist who was not involved in the study. "These results are highly relevant to the study, conservation, and management of long-lived species." "Juvenile survival, recruitment, population size, and effects of avian pox virus in Laysan Albatross (Phoebastria immutabilis) on Oahu, Hawaii, USA" will be available October 26, 2016, at http://americanornithologypubs. (issue URL http://americanornithologypubs. ). About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists' Union in 2016 to become the American Ornithological Society.

Loading Pacific Rim Conservation collaborators
Loading Pacific Rim Conservation collaborators