Little evidence that condition, stress indicators, sex ratio, or homozygosity are related to landscape or habitat attributes in declining woodland birds

Amos, J. Nevil; Balasubramaniam, Sasitharan; Grootendorst, L.; Harrisson, Katherine A.; Lill, Alan; Nally, Ralph Mac; Pavlova, Alexandra; Radford, James Q.; Takeuchi, Naoko; Thomson, James Robertson; Sunnucks, Paul

doi:10.1111/j.1600-048x.2012.05746.x

Cited by 21 publications

(15 citation statements)

References 88 publications

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“…Amos et al . () found no relationship between habitat fragmentation, vegetation condition and haematocrit or residual body mass of several woodland bird species, including superb fairy‐wrens. They suggest that such metrics of condition may not be sufficiently sensitive to show any difference caused by habitat change.…”

Section: Discussionmentioning

confidence: 94%

Chronic stress in superb fairy‐wrens occupying remnant woodlands: Are noisy miners to blame?

2019

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Interactions between competing species may be intensified when they are restricted to small patches of remnant habitat, potentially increasing physiological stress in individuals. The effects of interspecific competition on stress in wildlife remain largely unexplored. In Australia, remnant woodlands are often dominated by aggressive honeyeaters, especially the noisy miner (Manorina melanocephala). Harassment of smaller birds by miners may result in their exclusion from suitable woodland habitat. We tested whether the presence of noisy miners is also associated with elevated stress in a model species of small passerine bird, the superb fairy-wren (Malurus cyaneus). We sampled wrens from six sites, three remnant woodlands with noisy miners and three larger fragments of reserved habitat without noisy miners. Differential white blood cell counts were used to infer levels of chronic stress. We also assessed variation in body condition and the prevalence of blood parasites (Haemoproteus spp.) to test for associations between stress and parasitemia. The mean heterophil-to-lymphocyte (H:L) ratio was 1.8 9 higher among superb fairy-wrens living in miner-dominated woodlands, suggesting higher levels of chronic stress. Individuals with higher stress appeared to be in poorer condition, as indicated by fat scores and residual body mass. Prevalence of blood parasites was generally high and was highest in reserved habitat (59%) where miners were absent. Birds with blood parasites living in these habitats had higher H:L ratios but the intensity of infection and H:L ratio was inversely related. Our results suggest that birds persisting in the presence of noisy miners might experience chronic stress, but further study is necessary to separate the relative importance of noisy miner aggression from other potential stressors in small patches of degraded woodland. Stress induced by interspecific aggression should be considered in future studies of wildlife living in remnant vegetation.

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Section: Discussionmentioning

confidence: 94%

Chronic stress in superb fairy‐wrens occupying remnant woodlands: Are noisy miners to blame?

2019

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“…Neither habitat quality, nor the extent of tree‐cover, nor level of fragmentation in our study area influenced the body condition of fuscous honeyeaters, as assessed by morphometric and haematological variables (Amos et al . ). Thus, factors unrelated to reduced genetic connectivity or habitat quality (Ford et al .…”

Section: Discussionmentioning

confidence: 97%

Does reduced mobility through fragmented landscapes explain patch extinction patterns for three honeyeaters?

Harrisson

Pavlova

Amos

et al. 2014

Journal of Animal Ecology

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Summary 1.Habitat loss and associated fragmentation are major drivers of biodiversity decline, and understanding how they affect population processes (e.g. dispersal) is an important conservation goal. In a large-scale test employing 10 9 10 km units of replication, three species of Australian birds, the fuscous honeyeater, yellow-tufted honeyeater and white-plumed honeyeater, responded differently to fragmentation. The fuscous and yellow-tufted honeyeaters are 'decliners' that disappeared from suitable habitat in landscapes where levels of tree-cover fell below critical thresholds of 17 and 8%, respectively. The white-plumed honeyeater is a 'tolerant' species whose likelihood of occurrence in suitable habitat was independent of landscapelevel tree-cover. 2. To determine whether the absence of the two decliner species in low tree-cover landscapes can be explained by reduced genetic connectivity, we looked for signatures of reduced mobility and gene flow in response to fragmentation across agricultural landscapes in the Box-Ironbark region of north-central Victoria, Australia. 3. We compared patterns of genetic diversity and population structure at the regional scale and across twelve 100 km 2 landscapes with different tree-cover extents. We used genetic data to test landscape models predicting reduced dispersal through the agricultural matrix. We tested for evidence of sex-biased dispersal and sex-specific responses to fragmentation. 4. Reduced connectivity may have contributed to the disappearance of the yellow-tufted honey-eater from low tree-cover landscapes, as evidenced by male bias and increased relatedness among males in low tree-cover landscapes and signals of reduced gene flow and mobility through the agricultural matrix. We found no evidence for negative effects of fragmentation on gene flow in the other decliner, the fuscous honeyeater, suggesting that undetected pressures act on this species. As expected, there was no evidence for decreased movement through fragmented landscapes for the tolerant white-plumed honeyeater. 5. We demonstrated effects of habitat loss and fragmentation (stronger patterns of genetic differentiation, increased relatedness among males) on the yellow-tufted honeyeater above the threshold at which probability of occurrence dropped. Increasing extent and structural connectivity of habitat should be an appropriate management action for this species and other relatively sedentary woodland specialist species for which it can be taken as representative.

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“…This variable was found to be the strongest predictor of the presence of the fuscous honeyeater at a site (Radford and Bennett 2007) with values below the threshold of 17% corresponding to very low probability of species occurrence . Four site-scale vegetation condition scores, assessed for Amos et al (2013) using the 'habitat hectares' methodology (Parkes et al 2003) and believed to best represent habitat parameters relevant to breeding, feeding and vocalization of fuscous honeyeaters (Chan 1990), were included in the analysis. These were Large trees, number of large trees (with diameter at breast height greater than 0.7 m) per hectare (range 0-7, mean 2.4, SD 1.8 ), Tree height, average height (in meters) of all trees at a site (range 12-25.6, mean 13.7, SD 11.3), Canopy, projected percent of canopy cover by individual trees that are  80% of their mature height (range 15-30, mean 21, SD 4.0) and Shrubs, the sum of projected cover of small ( 1 m), medium (1-5 m) and large ( 5 m) shrubs (range 0-40, mean 13.7, SD 11.3; Supplementary material Appendix 1) (Parkes et al 2003).…”

Section: Landscape-and Site-scale Habitat Quality Variablesmentioning

confidence: 99%

Song parameters of the fuscous honeyeater Lichenostomus fuscus correlate with habitat characteristics in fragmented landscapes

Goretskaia

Beme

Popova

et al. 2018

Journal of Avian Biology

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Both avian abundance and species richness decline in response to habitat loss and fragmentation. Studying variation in bird song structure across modified landscapes can provide insights into the effects of habitat alterations on coherence of social interactions within populations. Here, we tested whether fragmentation or change of habitat quality within box-ironbark forest of central Victoria impacted cultural connectivity and song characteristics in fuscous honeyeater, a declining common Australian bird. First, we tested whether geographic distance and/or spatially-explicit landscape connectivity models can explain patterns of song similarity across fragmented landscapes. We found no evidence that distance or habitat fragmentation impacts the nature and transmission of fuscous honeyeater song, and concluded that acoustic connectivity at the scale of our study is high. Second, we tested whether variation in habitat quality explains variation in song characteristics. In accordance with acoustic adaptation to habitat structure, birds sang longer songs in sites with more large trees and produced longer common song elements in sites with greater tree height. However, the acoustic adaptation hypothesis cannot explain the finding that in less-disturbed landscapes with higher tree-cover birds sang songs (and song elements) with higher maximum frequency and wider frequency bandwidth. We also found that birds sing longer and more variable songs of wider frequency bandwidth in less disturbed sites with a greater number of large mature trees, which may represent better feeding resources. Our study suggests that changes in song structure with habitat degradation could signal disturbed population processess, such as changes in the acoustic communication among resident birds.

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Little evidence that condition, stress indicators, sex ratio, or homozygosity are related to landscape or habitat attributes in declining woodland birds

Cited by 21 publications

References 88 publications

Chronic stress in superb fairy‐wrens occupying remnant woodlands: Are noisy miners to blame?

Chronic stress in superb fairy‐wrens occupying remnant woodlands: Are noisy miners to blame?

Does reduced mobility through fragmented landscapes explain patch extinction patterns for three honeyeaters?

Song parameters of the fuscous honeyeater Lichenostomus fuscus correlate with habitat characteristics in fragmented landscapes

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