Ornithology

Wintering Black Terns Foraging Among Manta Rays in Coastal Guerrero, Mexico

by Keith Larson

Larson, K. W., and J. E. Martinez Leyva. 2007. Wintering Black Terns Foraging Among Manta Rays in Coastal Guerrero, Mexico. Waterbirds 30:448–449. doi: 10.1675/1524-4695(2007)030[0448:WBTFAM]2.0.CO;2.

Águia-cinzenta (Harpyhaliaetus coronatus) eo Gavião-real-falso (Morphnus guianensis) em Santa Catarina e Rio Grande do Sul: prioridades e desafios para …

by Ismael Franz

Predação da cobra d'água Helicops infrataeniatus (Serpentes, Colubridae) pela maria-faceira Syrigma sibilatrix (Aves, Ardeidae) no sul do Brasil.

by Ismael Franz

Dois casos de leucismo em quero-quero Vanellus chilensis (Molina, 1782) no sul do Brasil

by Ismael Franz

A new host record for Philornis (Diptera, Muscidae)

by Ismael Franz

Primeiros registros de Sula dactylatra lesson, 1831 (Pelecaniformes: Sulidae) no estado do Rio Grande do Sul, Brasil

by Ismael Franz

Ninhos de joão-de-barro Furnarius rufus (Aves, Passeriformes, Furnariidae) construídos sobre o solo no sul do Brasil

by Ismael Franz

Redescoberta de Mackenziaena severa (Lichtenstein, 1823)(Aves: Thamnophilidae) no limite sul de sua distribuição geográfica, Rio Grande do Sul, Brasil

by Ismael Franz

Bird community in a forest patch isolated by the urban matrix at the Sinos River basin, Rio Grande do Sul state, Brazil, with comments on the possible local …

by Ismael Franz

Registro da pomba-do-orvalho Patagioenas maculosa (Aves: Columbidae) no estado de Santa Catarina, sul do Brasil

by Ismael Franz

O atobá-pardo Sula leucogaster no Rio Grande do Sul, sul do Brasil: sete novos registros documentados e revisão do status regional de ocorrência

by Ismael Franz

The winter range of Nearctic Purple Sandpipers Calidris maritima on the East Atlantic flyway

by Gunnar Thor Hallgrimsson

Published 2012 in Ardea 100: 13-18

Iceland has a large resident population of Purple Sandpipers Calidris maritima, but is also believed to be a wintering... more Iceland has a large resident population of Purple Sandpipers Calidris maritima, but is also believed to be a wintering area for other populations and is a stopover site for migrants. To determine the wintering areas of those that prepare for westward migration to the Nearctic in spring, Purple Sandpipers were colour-ringed on the coast of southwest Iceland in May 2003 and 2005. We searched for colour-ringed birds along the coasts of Iceland, the European mainland and Britain, particularly in winter 2005/06. Out of 326 marked birds, 82 were re-sighted during 2003 to 2009, of which 69 were seen during winter (October to March) 2005/06. Most sightings (55) in winter 2005/06 were from southwest Iceland, extending the known winter range of this population toIceland. Resightings from northern Scotland confirmed the evidence from biometrics that this wintering population originates from the Nearctic. The maximum number of colour-marked Purple Sandpipers in Britain and Ireland in winter 2005/06 was estimated at about 65, which was approximately a quarter of the marked sample estimated to be alive. Therefore, the majority of the colour-ringed birds must have wintered elsewhere, most likely in Iceland. There was no evidence of sexual segregation according to whether they wintered in Iceland or Britain. However, those that were colour-ringed before 15 May were more likely to be seen in Iceland than in Britain, whereas those colour-ringed after 15 May were more likely to be seen in Britain, indicating that the migration from Britain takes place mainly after mid-May. Although there have been no ringing recoveries, biometry data suggest that Purple Sandpipers that prepare for westward migration in Iceland in spring, breed in Canada. This population shows a unique winter range for a wader that includes Greenland, Iceland and northwest Europe along the East Atlantic flyway.

Impacts of grassland farming on the Whinchat (Saxicola rubetra): appropriate conservation measures for a threatened grassland bird in the Goms valley, Switzerland

by Gavino Strebel

MSc Dissertation, University College London

The Whinchat, a meadow-breeding passerine, is a typical example of a farmland bird that has strongly declined in the... more The Whinchat, a meadow-breeding passerine, is a typical example of a farmland bird that has strongly declined in the last decades in many parts of Europe. The main reason for its decline has been ascribed to an onset of the mowing period, which leads to nest loss and has made the bird disappear from most lowland areas in Europe. In Switzerland, a population stronghold remains in the Goms valley, which, however, is increasingly threatened by earlier mowing. In this study, the conflict between the breeding phenology and the mowing schedule has been established for seven sites on different expositions in the Goms valley. Detailed records of areas mown were compared with key data collected on breeding phenology and Whinchat territories in order to quantify the magnitude of this conflict, which strongly affects the survival of Whinchat populations. The conflict was most pronounced in the intensively farmed, early mown valley bottoms while being less distinctive for meadows mown on the slopes. Differences were also found between sites. Based on the analysis of the conflict, recommendations for the conservation of the important inneralpine population in the Goms valley were made. The findings show that in order to halt the decline of Whinchats in the Goms valley, it is necessary to postpone mowing until the 7th of July at the least.

Breeding Double-Crested Cormorants and Wading Birds on Isla Alcatraz, Sonora, México

by Jennifer Duberstein

Food availability and offspring sex in a monogamous seabird: insights from an experimental approach

by Sarah Leclaire

Sex allocation theory predicts that parents should favor offspring of the sex that provides the greatest fitness... more Sex allocation theory predicts that parents should favor offspring of the sex that provides the greatest fitness return. Despite growing evidence suggesting that vertebrates are able to overcome the constraint of chromosomal sex determination, the general pattern remains equivocal, indicating a need for experimental investigations. We used an experimental feeding design to study sex allocation during 3 years in black-legged kittiwakes (Rissa tridactyla). Intense male–male competition for securing a breeding site is common in this species in which males are heavier and larger than females. Hence, we hypothesized that parents producing fledglings in better than average condition, as supplementarily fed pairs do, would increase their fitness return by producing sons. Conversely, producing daughters would be a better tactic for Unfed parents. Hence, we predicted that Fed parents produce more sons than Unfed parents. This prediction is particularly expected if sexual dimorphism arises as early as during chick rearing, suggesting strong selective pressures for optimal male development. Our results showed that 1) males were heavier and larger than females prior to fledging and that 2) Fed parents produced relatively more male hatchlings than Unfed parents. We interpret this result in terms of a Trivers–Willard-type process. Furthermore, our data revealed that Unfed parents significantly overproduced female hatchlings, whereas offspring sex ratio was balanced among Fed parents. Because the 3 reproductive seasons we considered were particularly poor food years, Unfed parents may have overproduced daughters to avoid the apparent higher reproductive costs of raising sons.

AN ETHNOORNITHOLOGICAL APPROACH TO HUMAN-BIRD RELATIONS AMONG THE MOPAN MAYA OF BELIZE

by Kerry Hull

Eagles in Mesoamerican Thought and Mythology

by Kerry Hull

Co-authored with Rob Fergus

Three possible nest-relief factors in the American Kestrel (Falco sparverius)

by Juan Martínez-Gómez

Journal of Raptor Research  25:: 88-89. 1991.

Raptor conservation in Veracruz

by Juan Martínez-Gómez

Journal of Raptor Research 26: 184-188. 1992

This article presents aspects of raptor conservation, including training of local students, developing networks to... more This article presents aspects of raptor conservation, including training of local students, developing networks to monitor bird trade and to protect natural areas, establishing banding stations in Veracruz, ecotourism, and cooperative efforts among raptor biologists in North America and Veracruz. Because 67 raptor species are found in Veracruz, Mexico, and because the most northern high rainforest of the continent is located in this Mexican State, a major conservation effort in this region is certainly warranted.

Sexual size dimorphism and food requirements of nestling birds

by Juan Martínez-Gómez

Canadian Journal of Zoology 71: 2541-2545. 1993.

The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio,... more The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.