Thrush Species Research Articles

Do Avian Frugivores Absorb Fruit Sugars Inefficiently? How Dietary Nutrient Concentration Can Affect Coefficients of Digestive Efficiency

Fruit-eating birds are thought to inefficiently digest and/or assimilate nutrients from fruits. Contradicting this established premise, I found that Cedar Waxwings Bombycilla cedrorum and three thrush species absorbed fruit sugars efficiently, comparable to levels of sugar assimilation shown by nectar-feeding birds. Relatively low sugar digestive efficiencies by birds eating Lonicera morowii fruit could be explained by the especially low sugar solute concentration of this fruit's pulp. Sugar digestive efficiency is a proportional measure of sugar extraction from ingested sugar solutions. When most ingested water is excreted with unabsorbed sugars, digestive efficiency will decline as fruit sugar concentration decreases if sugars are reduced to relatively constant, minimum concentrations in excreted water. Under this circumstance, fecal nutrient concentration may be more appropriate for comparisons of how well animals utilize nutrients from foods that differ in their concentrations of dissolved or dispersed nutrients. Efficient absorption of fruit sugars by Cedar Waxwings and thrushes contradicts the premise that sugary, bird-dispersed fruits challenge the digestive systems of avian frugivores so that nutrient utilization is impaired. Because simple sugars (glucose and fructose) are readily assimilated, digestive processing of sugary fruits is more rapid than processing of foods containing complex nutrients. Thus, fruits represent accessible, energy-rich foods from which nutrients are efficiently absorbed by avian frugivores.

Interspecific synchrony and asynchrony in the fruiting phenologies of congeneric bird-dispersed plants in Panama

Plants potentially compete for seed dispersal. Selection may favour temporally segregated fruiting phenologies to minimize this competition and also to maintain resident populations of dispersal agents. Alternatively, selection may favour temporally aggregated fruiting phenologies when the effectiveness of seed dispersal agents varies seasonally or when large, synchronous fruit displays enhance dispersal. These evolutionary scenarios assume that plants share seed dispersal agents. This assumption and temporal overlap in fruiting phenologies were evaluated for the Miconia and Psychotria of central Panama. These two genera accounted for 18 and 27%, respectively, of 1096 fleshy fruits found in regurgitation or faecal samples taken from 2054 birds of 103 species netted in the forest understorey. Two species of manakins accounted for 62% (123/200) of all Miconia fruit taken. Three species of manakins and three species of migratory thrushes accounted for 97% (282/292) of all Psychotria fruits taken. There is a high potential for intrageneric competition for seed dispersal for both plant genera. Null model analyses showed that the fruiting phenologies of Miconia (14 species) are segregated in time, while fruiting of Psychotria (21 species) is highly aggregated. The Miconia were found in up to 24% of the diet samples for the two manakin species, suggesting that Miconia may be a critical resource for both species. The Psychotria fruited when the diversity of understorey fruits was greatest, suggesting a high potential for both intra- and extrageneric competition. The abundance and nomadism of the six bird species that consumed most Psychotria fruit peaked when the Psychotria fruited, supporting the enhancement hypothesis.

Trends in the abundance of farmland birds: a quantitative comparison of smoothed Common Birds Census indices

1. Widespread declines in the populations of many British farmland birds have occurred since the early 1970s. We must understand the causes of these declines tomake recommendations about conservation and agricultural management, andthis can be approached by investigating the relationships, across species, betweenabundance and agricultural change. We describe novel, quantitative approaches to the interpretation of abundance indices from which reliable inferences about conservation status can be made. 2. We calculated farmland Common Birds Census indices for 42 species, smoothed the series to reveal underlying trends and estimated confidence intervals for the changes in abundance. 3. Between 1968 and 1995, the abundance of 12 species declined significantly andthat of 14 species increased. 4. Specialization was the only significant determinant of changes in abundance (of 10 tests against species characteristics): 13 farmland specialists declined, on average, by 30%, whilst 29 more generalist species underwent an average increase of 23%, confirming that farmland birds should engender conservation concern. 5. Smoothed abundance curves, transformed to emphasize trend direction and timing, were then compared quantitatively to identify whether groups of species had shared common trends. 6. Species tended not to be strongly grouped, but small groups of species with common trends were identified. Similarities in ecology among grouped species clarify the possible environmental causes of their population trends, indicating future research priorities. 7. The groups identified included: one group consisting of three thrush species Turdus and the skylark Alauda arvensis L. which all declined from the mid‐1970s after being stable previously; one group comprising three trans‐Saharan migrant warblers (Sylvidae), whose abundance fell in the early 1970s and later increased; and a diverse group of six smoothly increasing species. 8. Turning points were identified as where each species’ population trend turned significantly, revealing critical periods during which populations are likely to have been affected by environmental change. 9. Three collections of downward turning points were found, including one in the mid‐1970s when many farmland bird declines began. Four other periods each included many upturns. The groups of turning points should facilitate the identification of environmental changes which have had widespread effects. Management prescriptions can then be designed to reverse or to mirror such key changes and thereby focus conservation effort effectively.

Bird ringing in Britain and Ireland in 1995

This is the 59th annual report of the British Trust for Ornithology's Ringing Scheme and reports on the data received in 1995. 859,252 birds of 261 species were ringed. New species added to the Ringing Scheme's list were Hermit Thrush and Brünnich's Guillemot. There were small increases in the numbers of full‐grown birds (+0.3%) and nestlings (+2.1%) ringed. Changes in numbers of individual species, which cannot be explained by changes in ringer effort, included increases in Redstart and Cetti's Warbler and decreases in Long‐eared Owl and Brambling. It was probably the lack of cold weather which reduced the number of recoveries (12,415, down by 6%). The development of the Scientific Strategy of the BTO Ringing Scheme is discussed. Analysis of ringing and recovery data for Song Thrush showed that the significant change in the survival rate of juvenile birds is sufficient to explain the decline in population size. Work on Canada Geese identified factors associated with mobility which should be taken into account when considering control measures. Standardised summer catches at 114 Constant Effort Sites (CES) indicated good numbers of breeding song‐birds and good or average breeding success. However, declining catches of several finch and thrush species continued in 1995. Recovery data for over 50 species were provided to ornithologists for their research work.

Competence of a migratory bird, red-bellied thrush ( Turdus chrysolaus), as an avian reservoir for the Lyme disease spirochetes in Japan

To evaluate the competence of migratory birds as reservoirs for the Lyme disease spirochetes, we examined two species of migrants, Red-bellied thrush ( Turdus chrysolaus) and Black-faced bunting ( Emberiza spodocephala) in Nemuro, the northern part of Japan. Spirochetes were found in four individual birds out of 11 T. chrysolaus, three isolates were detected from the skins and the other one was obtained from the liver. No spirochete was found to be infected in 20 E. spodocephala. As far as we know, this is the first record of direct detection of the spirochetes from migratory birds in Japan. The spirochetes were also isolated from immature ixodid ticks, Ixodes persulcatus, fed on those species of birds. The spirochetes were transmitted trans stadially to the next stage, when infected ticks molted. All of the isolates from birds and ticks were identified as Borrelia garinii by our ribotyping and flagellin gene sequence analyses. Our results strongly suggest that the migratory birds are reservoirs in the transmission of the Lyme disease spirochetes in Japan.

Incidence of Second Broods by Wood Ducks in Alabama and Georgia

Second brood production by wood ducks (Aix sponsa) nesting in eastcentral Alabama and westcentral Georgia was -6.9 and 11.5% of successful nests in 1985 and 1986, respectively. There was a negative correlation (r = -0.86) between latitude and percent of hens producing second broods. Second broods increased production of flight-stage birds an estimated 1.1-2.6% in 1985 and 2.0-4.7% in 1986. The interval between hatch of the first clutch and initiation of the second clutch was 15-51 days in 1985 and 17-72 days in 1986. Thus, because wood duck females remain with their broods from 31 to 60 days, we concluded that some females that double-brooded either abandoned the first brood to initiate a second nest, initiated the second nest concurrent with brood rearing, or initiated the second nest after loss of the first brood. J. WILDL. MANAGE. 52(3):426-431 Most species of birds raise only 1 brood/year because time required for courtship, nest-building, incubation, and rearing young precludes fledging a second brood during the breeding season. However, some groups such as passeriforms and columbiforms regularly fledge >2 broods/reproductive period (Lack 1968, Westmoreland et al. 1986). Waterfowl normally do not hatch >1 clutch/ season, but many species renest if the first clutch is destroyed (Bellrose 1980). Wood ducks are an exception; however, because production of 2 broods has been recorded with regularity (Fredrickson and Hansen 1983). Double-brooded females were those that successfully hatched 2 broods in 1 reproductive season (Fredrickson and Hansen 1983). Brood survival was not assumed, although some ducklings from first and second broods of double-brooded females ultimately survived to flight stage. Fredrickson and Hansen (1983) also noted that existing reports of second broods were from above 36*N latitude and suggested that the frequency of double broods may be higher farther south. In passerines, for example, 2 species of thrushes (Turdus merula and T. philomelos) nesting in northern Europe fledge only 1 brood/ season, but conspecifics nesting farther south fledge 2-3 broods/season (Mayer-Gross and Perrins 1962). The objectives of our study were to document the frequency of second broods by wood ducks nesting in eastcentral Alabama and westcentral Georgia, assess the effect of latitude on the occurrence of second broods, and estimate the contribution of second broods to production. We thank D. E. Temple, W. D. Rundle, and the staff at Eufaula National Wildlife Refuge for their interest and assistance during this project. M. K. Causey, R. E. Mirarchi, and N. R. Holler reviewed the manuscript. This project was funded by the Alabama Division of Game and Fish through Federal Aid in Wildlife Restoration, Project W-44. This is publication 15871210 of the Alabama Agricultural Experiment Station.

Long‐term defence of fruit by Mistle Thrushes Turdus viscivorus

In an area of south‐central England Mistle Thrushes Turdus viscivorus regularly defend fruit‐hearing plants (four kinds of tree, ivy and mistletoe) against intruders from autumn to early spring. Holly Ilex aquifolium is by far the most important of the plants defended. To be suitable for defence, a tree must be free‐standing and of moderate size. Observations were carried out over three winters, one mild, one very severe and one intermediate. During the mild winter hollies were successfully defended until the Mistle Thrushes gave up active defence with the onset of breeding activities. During the very severe winter nearly all defended hollies were overwhelmed by invading flocks of other thrush species during the very cold spells. Mistle Thrushes in possession of a fruit supply conserve it by feeding on undefended fruit near‐by if it is available, and to a large extent on the ground when conditions are suitable. Defended fruit trees are generally avoided by other species living in the vicinity. Hence depletion of fruit from defended trees is much slower than from undefended trees, and consequently the fruit may last for several months and provide a food supply in dry weather in spring and early summer for Mistle Thrushes and other species.Fieldfares and Blackbirds show similar, but less well developed, fruit‐guarding behaviour. Fruit‐defence is clearly related to the bird's size, but other physical and behavioural adaptations may be involved. The most important characteristic of holly fruit making it suitable for defence, apart from the dimensions and spatial relationship of the tree, is its ability to last for many months without significant deterioration.

The Distribution of an Avian Guild along a Temperate Elevational Gradient: The Importance and Expression of Competition

A guild of ground—foraging, insectivorous birds which seasonally occupy montane temperate forests was investigated. By examining the roles of interspecific competition and specific habitat selection, I have dissected the factors controlling the distribution patterns of the guild members along extensive elevational gradients. The guild was composed of Hylocichla mustelina (Wood Thrush), Catharus fuscescens (Veery), C. guttatus (Hermit thrush), C. ustulatus (Swainson's Thrush), and C. minimus (Gray—cheeked Thrush). The five thrush species are sympatric on high mountains in the northeastern United States, but as one proceeds southward down the Appalachian Mountain chain, the species drop out one at a time. Anecdotal information indicated that the species showed elevational amptitude expansion as members of the guild dropped out with decreasing latitude. As a consequence of the opportunity for ecological release in southern latitudes, the thrush guild was ideally suited for testing the role of competition in determining distributional limits of the species when sympatric. I studied the behavioral interactions and habitat selection of the five species in sympatry on high mountains in the northeastern United States. The species have distinct distributions along these elevational gradients, but large spatial overlaps between adjacent species were observed. To test for significant differences in habitat selection, the breeding territories of these species were quantified by measuring 55 structural habitat variables. Using stepwise discriminant function analysis, I detected statistically significant differences in the species' breeding habitats. By employing a subset of 9 of the initial 55 variables, over 77% of the Northeastern habitat quantifications were assigned to the correct species group. Additional information extracted from the structural niche analysis indicated the habitat niche breadth of each species and the degree of habitat overlap between adjacent species, and provided insight into the limiting similarity allowed between these coexisting species. Song playback was used to test the contribution of behavioral interactions to the observed distribution patterns. All species showed greater response to conspecific song. The results indicated that over interspecific behavioral interactions contributed little or nothing to the observed distributional and specific habitat selection patterns of these species. To test the contribution of interspecific competition to the habitat selection patterns detected on Northeastern mountains, a subset of the five—member guild was studied on Southeastern mountains. In the Smoky Mountain range only H. mustrelina and C. fuscescens breed. By employing identical quantification techniques, I tested for expansion by these two species into habitat types not occupied when sympatric with the other three species. Evidence of extensive ecological release was obtained, implying a strong role for interspecific competition in Northeastern mountains. Thus, my results further implicate interspecific competition as an integral force contributing to the organization of temperate bird communities.

Oxygen consumption in relation to ambient temperature in five species of forest-dwelling thrushes ( Hylocichla and Catharus)

1. 1. The standard metabolic rates of five forest-dwelling thrushes ( Hylocichla mustelina, Catharus fuscescens, C. guttatus, C. ustulatus and C. minimus) resting in the dark at thermoneutrality during their normal active period averaged 14·8 per cent below values predicted by Aschoff & Pohl (1970) but were nearly identical to the values predicted by Lasiewski & Dawson (1967). 2. 2. Oxygen consumption of these five thrushes is a linear function of air temperature below speciesspecific lower critical temperatures. 3. 3. The only statistically significant difference ( P>0·95) between regression equations relating metabolism below thermoneutrality to ambient temperatures among the five species was that between C. minimus and C. ustulatus. 4. 4. The flatter slope exhibited by C. minimus may represent a metabolic adjustment to the more rigorous environment at high elevations which it alone inhabits.

The Relationships of the Wood Thrush (Hylocichla mustelina): Some Indications from the Electrophoresis of Blood Proteins

The generic relationships of the Wood Thrush (Hylocichla mustelina) have been called into question by the works of Dilger (1956) and Bourns (1967). The four species of North American woodland thrushes presently referred (32nd Supplement to the A.O.U. Checklist 1973) to the genus Catharus i.e., Hermit Thrush (Catharus guttata); Gray-cheeked Thrush (C. minima); Swainson's Thrush (C. ustulata); and Veery (C. fuscescens) were formerly placed in the genus Hylocichla (A.O.U. Check-list 1957) and were long believed to be the closest relatives of the Wood Thrush.

Temperature Regulation of the Pyrrhuloxia and the Arizona Cardinal

Temperature Regulation of the Pyrrhuloxia and the Arizona Cardinal

Relationships between Two Partly Sympatric Species of Thrushes (Catharus) in Mexico

Relationships between Two Partly Sympatric Species of Thrushes (Catharus) in Mexico

A new species of Thrush from Angola

A new species of Thrush from Angola

On Turdus celaenops

Turdus celaenops is a distinct species of thrush confined to the Seven Islands of Izu except Torishima. Its visit to the main island was recorded on five occasions. T. dissimilis of Burma and Yunnan, T. seebohmi of Borneo, T. obsourus, T. hortulorum and T. chrysolaus of the Palacarctic region are considered near relatives to T. celaenops. It is suggested that celaenops, chrysolaus, obscurus and dissimilis were derived from a same ancestral stock on the Asiatic continent and since the arrival of one strain to the Seven Islands, through selections and mutations, the present form, celaenops, was developed. Because the general resemblance in the plumage and the wing formula, celaenops is nearest related to chrysolaus.Yakushimensis, the only known subspecies in Yakushima, is not considered valid and; as these subspecies have been taken only in October, Yakushima birds were probably migrants from the Seven Islands. Parallel cases are phylloscopus occipitalis ijimae and Luscinia akahige tanensis, the Seven Islands breeding subspecies which are known to winter in Yakushima and further south to the Ryukyu Islands.

Description of a new species of ant thrush from Nicaragua

Description of a new species of ant thrush from Nicaragua

III.-Description of a New Species of Thrush from the Island of Grenada, West Indies

III.-Description of a New Species of Thrush from the Island of Grenada, West Indies

Diagnosis of a New Species of Thrush (Turdus celaenops sp. nov.) from Japan

Diagnosis of a New Species of Thrush (Turdus celaenops sp. nov.) from Japan

Wells and Lawrence on the Birds of Grenada, West Indies A Catalogue of the Birds of Grenada, West Indies, with Observations Thereon John Grant Wells George N. Lawrence Description of a New Species of Thrush from the Island of Grenada, West Indies George N. Lawrence

Wells and Lawrence on the Birds of Grenada, West Indies A Catalogue of the Birds of Grenada, West Indies, with Observations Thereon John Grant Wells George N. Lawrence Description of a New Species of Thrush from the Island of Grenada, West Indies George N. Lawrence

On a new Species of Thrush from Timor Laut, with remarks on some rare Birds from that Island and from the Moluccas

On a new Species of Thrush from Timor Laut, with remarks on some rare Birds from that Island and from the Moluccas

6. On certain obscure Species of Siberian, Indian, and Chinese Thrushes

Proceedings of the Zoological Society of LondonVolume 47, Issue 1 p. 803-806 6. On certain obscure Species of Siberian, Indian, and Chinese Thrushes Henry Seebohm, Henry SeebohmSearch for more papers by this author Henry Seebohm, Henry SeebohmSearch for more papers by this author First published: January 1879 https://doi.org/10.1111/j.1096-3642.1879.tb02719.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume47, Issue1January 1879Pages 803-806 RelatedInformation