Changes in Timing, Duration, and Symmetry of Molt of Hawaiian Forest Birds

Freed, Leonard A.; Cann, Rebecca L.

doi:10.1371/journal.pone.0029834

Cited by 36 publications

(56 citation statements)

References 49 publications

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“…In the same study, primary-feather asymmetry decreased as the amount of subcutaneous fat stored during molt increased. In a nonexperimental study, the causal effect of food limitation on molt asymmetry was demonstrated for a group of Hawaiian forest avian species (Freed and Cann 2012). It was also found that Common Whitethroats (Sylvia communis) starting molt late in the season showed a higher degree of asymmetry in feather replacement than early-molting individuals (Hall and Fransson 2001), and the authors suggested that this pattern could be attributed to high metabolic rate caused by the stress of molting late in the year.…”

Section: Discussionmentioning

confidence: 94%

Relationship of Hemoglobin Concentration to Packed Cell Volume in Avian Blood Samples

Velguth

Payton²,

Hoover³

2010

Journal of Avian Medicine and Surgery

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Section: Discussionmentioning

confidence: 94%

Relationship of Hemoglobin Concentration to Packed Cell Volume in Avian Blood Samples

Velguth

Payton²,

Hoover³

2010

Journal of Avian Medicine and Surgery

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“…During 2005, prevalence of non-normal molt was lowest in the closed forest site, but became highest in 2006 (Freed and Cann 2012). This reversal was associated with increased density of white-eyes in the closed forest area and decreased density in the open forest area between 2005 and 2006 (Fig.…”

Section: Speciesmentioning

confidence: 90%

“…Changes included lower mass, lower fat, shorter legs, and shorter bills (Freed et al 2008a,b;, which generated lower juvenile and adult survival. In addition, we identified changes in timing, duration, and symmetry of molt of all native species, with increasingly lower survival during the winter months of 2000(Freed and Cann 2012. These changes in molt have been experimentally induced by severe food limitation in other birds (Murphy et al 1988, Swaddle andWitter 1994).…”

Section: Speciesmentioning

confidence: 99%

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Increase of an introduced bird competitor in old-growth forest associated with restoration

Freed¹,

Cann²

2012

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Citation: Freed LA, Cann RL (2012) Increase of an introduced bird competitor in old-growth forest associated with restoration. NeoBiota 13: 43-60. doi: 10.3897/neobiota.13.2946 AbstractMany successful invasions involve long initial periods in which the invader exists at low densities followed by sudden population increases. The reasons for such time-lags remain poorly understood. Here we document a sudden increase in density of the introduced Japanese white-eye (Zosterops japonicus) in a restoration area contiguous with old-growth forest at Hakalau Forest National Wildlife Refuge on the Island of Hawaii. The refuge, with very high density of native birds, existed in a pocket of low whiteeye density that persisted for at least 20 years since the late 1970s. The refuge began an extensive native trees restoration project in 1989 within a 1314 ha abandoned pasture above old-growth forest. This area was soon colonized by white-eyes and their population grew exponentially once the trees had grown tall enough to develop a canopy. This increase was in turn followed by significantly more white-eyes in the open and closed forests adjacent to the restoration area. Competition between white-eyes and native species was documented on study sites within these forests. Density data indicate that competition was more widespread, with loss of tens of thousands of native birds in the 5371 ha area surveyed. Our results are consistent with the view that ecological barriers may delay the population increase of invaders and that human-derived activities may help invaders cross these barriers by creating new ecological opportunities. Control of white-eye numbers may be essential for recovery of native species.

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“…Frog muscle tissue turns over roughly 60-80 days (Cloyed et al 2015), Hawaiian bird feather molt takes about 90-120 days (Freed and Cann 2012), and bat wing membrane tissue turnover is about 50 days (Roswag et al 2015). Because the turnover rates for all these tissues are within 2-6 months, we felt that all samples collected for isotope analyses reflected the resource base for that year and should be comparable.…”

Section: Sample Collectionmentioning

confidence: 99%

Different prey resources suggest little competition between non-native frogs and insectivorous birds despite isotopic niche overlap

Smith

Beard

Shiels³

2016

Biol Invasions

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Non-native amphibians often compete with native amphibians in their introduced range, but their competitive effects on other vertebrates are less well known. The Puerto Rican coqui frog (Eleutherodactylus coqui) has colonized the island of Hawaii, and has been hypothesized to compete with insectivorous birds and bats. To address if the coqui could compete with these vertebrates, we used stable isotope analyses to compare the trophic position and isotopic niche overlap between the coqui, three insectivorous bird species, and the Hawaiian hoary bat. Coquis shared similar trophic position to Hawaii amakihi, Japanese white-eye, and red-billed leiothrix. Coquis were about 3 % less enriched in d 15 N than the Hawaiian hoary bat, suggesting the bats feed at a higher trophic level than coquis. Analyses of potential diet sources between coquis and each of the three bird species indicate that there was more dietary overlap between bird species than any of the birds and the coqui. Results suggest that Acari, Amphipoda, and Blattodea made up[90% of coqui diet, while Araneae made up only 2% of coqui diet, but approximately 25% of amakihi and white-eye diet. The three bird species shared similar proportions of Lepidoptera larvae, which were *25% of their diet. Results suggest that coquis share few food resources with insectivorous birds, but occupy a similar trophic position, which could indicate weak competition. However, resource competition may not be the only way coquis impact insectivorous birds, and future research should examine whether coqui invasions are associated with changes in bird abundance.

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Changes in Timing, Duration, and Symmetry of Molt of Hawaiian Forest Birds

Cited by 36 publications

References 49 publications

Relationship of Hemoglobin Concentration to Packed Cell Volume in Avian Blood Samples

Relationship of Hemoglobin Concentration to Packed Cell Volume in Avian Blood Samples

Increase of an introduced bird competitor in old-growth forest associated with restoration

Different prey resources suggest little competition between non-native frogs and insectivorous birds despite isotopic niche overlap

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