Mercury concentrations provide an indicator of marine foraging in coastal birds

We examined numbers of rectrices of all subspecies of blue grouse (Dendragapus obscurus), determined from our own studies and reported in the literature. Approximately 8% of all birds had an uneven number of rectrices, with no difference between males and females. More birds from a presumed subspecific "hybrid" population had uneven numbers of rectrices than those from "nonhybrid" samples. Of North American tetraonines, sage grouse (Centrocercus urophasianus) and blue grouse appear most variable in this character. Within subspecies, males and females had the same modal numbers of rectrices. The sexes differed, however, in the overall distribution of numbers of rectrices; most birds with submodal numbers were females and most birds with supermodal numbers, males. Males and females in one hybrid population differed in modal numbers of rectrices: males 20, and females 18. Eighty per cent of all coastal blue grouse had 18 rectrices, with no differences among subspecies. In contrast, all interior subspecies differed from each other. The two northern interior subspecies, D. o. pallidus and D. o. richardsonii, had modes of 20 rectrices, with that for pallidus weaker than that for richardsonii (70 and 81% modal, respectively). Dendragapus obscurus obscurus had a mode of 18 rectrices, not different from that for coastal birds. A small sample of D. o. oreinus was equally divided between birds with 18 and 20 rectrices, suggesting relationships with D. o. pallidus to the north and D. o. obscurus to the east. Northern interior blue grouse emerge as a distinct group with respect to modal number of rectrices, which parallels the pattern for the presence or absence of tail bands. Based on these two characteristics, coastal blue grouse appear more closely related to southern interior than to northern interior subspecies. The blue grouse is the only tetraonine with clear evidence of subspecific variation in numbers of rectrices.

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Declining populations of coastal birds in Great Britain: victims of sea-level rise and climate change?

Environmental Reviews ◽

10.1139/a00-011 ◽

2000 ◽

Vol 8 (4) ◽

pp. 303-323 ◽

Cited By ~ 2

Author(s):

K Norris ◽

P W Atkinson

Keyword(s):

Climate Change ◽

Great Britain ◽

Sea Level Rise ◽

Sea Level ◽

Habitat Loss ◽

Current Status ◽

Anthropogenic Factors ◽

Important Species ◽

Bird Populations ◽

Coastal Birds

Is sea-level rise and (or) climate change responsible for current declines in important coastal bird populations in Great Britain, and how might these processes affect bird populations in future? We review the current status of coastal bird populations in Britain and identify two important species, Common Redshank (Tringa totanus) and Twite (Carduelis flavirostris), whose populations are currently declining. We then review the evidence relating to the causes of these declines. There is evidence that habitat loss, driven by sea-level rise and climate change (e.g., an increase in wind and wave energy reaching the coast due to an increase in the frequency of storms), could have contributed to the decline in Twite. Common Redshank numbers are declining because of changes in grazing management, not sea-level rise. Populations that are currently stable or increasing, such as wintering waders and wildfowl, might in future experience declines in abundance because there is a link between climate, food supply, and bird abundance. There are insufficient reliable data at present to allow us to predict future changes with any confidence. Sea-level rise and climate change are currently important issues facing coastal zone management in Great Britain, and these issues may become even more pressing in future. But, in addition to these environmental processes, coastal bird populations are affected by a range of other anthropogenic factors. Conservationists, therefore, need to identify important bird populations that are (or could be in future) detrimentally affected by any of these activities rather than focusing exclusively on single issues such as sea-level rise. Allowing the sea to breach existing sea defences, thereby creating new saltmarsh, provides a way forward but is not without its practical and political difficulties.Key words: coastal birds, sea-level rise, climate change, population decline, habitat loss, saltmarsh.

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Mixed evidence for effects of stewardship on Least Tern reproductive success in coastal Mississippi

The Condor ◽

10.1093/condor/duaa050 ◽

2020 ◽

Author(s):

Abigail J Darrah

Keyword(s):

Sandy Beaches ◽

Chick Survival ◽

Least Terns ◽

Least Tern ◽

Daily Nest Survival ◽

Coastal Birds ◽

Total Productivity ◽

Work Shifts ◽

Breeding Seasons ◽

Positive Effect

Abstract Disturbance from human activity can cause reduced productivity of coastal birds that nest on sandy beaches. A common method to protect coastal birds from human disturbance is the use of signs and fencing to close off a section of beach used for breeding. This management action requires public compliance and might require enforcement, such as in the use of volunteer stewards stationed at protected colonies that provide education and enforcement. I assessed the effectiveness of active stewardship as a conservation measure to protect nesting Least Terns (Sternula antillarum) in coastal Mississippi by determining if colony-level productivity (fledglings produced per nest) was correlated with stewardship effort (hours that stewards protected each colony), the rate of disturbance from human and natural sources, and additional factors. Observers surveyed 24 Least Tern colonies in Harrison County, Mississippi, twice weekly during the 2017–2019 breeding seasons to record the number of nests present, the fate of marked nests, predator tracks within the colony, and the number of fledglings produced per colony. Concurrently, during their work shifts, stewards recorded all sources and durations of disturbance events that caused the terns to flush or respond with defense. Least Tern daily nest survival increased with colony size and stewardship effort, and was lower during intervals that included weekends and evidence of owl presence. Total productivity was negatively associated with avian predator disturbance rate and the total time adults spent flushed, but was not associated with stewardship effort. The results of this study demonstrate that active stewardship can have a positive effect on Least Tern productivity by increasing nest success, whereas current stewardship practices were not sufficient to increase chick survival, even in a system with a paucity of ground predators.

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Pacific Coast and Southwest Interior Populations of the Hutton's Vireo Differ in Basic Song Parameters

The Condor ◽

10.1093/condor/102.4.911 ◽

2000 ◽

Vol 102 (4) ◽

pp. 911-914

Author(s):

Colette T. Baril ◽

Jon C. Barlow

Keyword(s):

Pacific Coast ◽

Pairwise Comparison ◽

Genetic Differences ◽

Minimum Frequency ◽

Acoustical Properties ◽

Frequency Measurements ◽

Coastal Birds ◽

Comparison Level

Abstract Comparisons of song parameters, including syllable length and maximum and minimum frequency, from six populations of the Hutton's Vireo (Vireo huttoni) show differences in syllable length and minimum frequency measurements. Specifically, syllables produced by Pacific coastal birds tend to be shorter than those from southwest interior populations, although these differences are not statistically significant at the pairwise-comparison level. Syllables produced by most coastal populations have significantly higher mean minimum frequencies when compared with those from interior populations. Differences between songs of coastal and interior populations are consistent with genetic differences that separate the two groups. Differences in song may be attributed to the acoustical properties of coastal versus interior habitats.

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