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Sexual dimorphism in bill size can lead to sex-specific foraging strategies. All 12 extant species of oystercatchers (Haematopus spp.) have sexually dimorphic bills, and most oystercatcher species show intersexual niche partitioning in diet, where males and females eat different prey species in different proportions. Intersexual niche partitioning in diet has not been examined in American Oystercatchers (Haematopus palliatus). This study tested for intersexual niche partitioning in diet in a population of American Oystercatchers breeding on two barrier islands in coastal Virginia, U.S.A. in 2022 and 2023. Diet composition, prey size selection, and foraging areas were compared between the sexes (n = 31 males and n = 28 females). Unlike other oystercatcher species, male and female American Oystercatcher diets overlapped by 99%. Both sexes took similar-sized prey across the seven prey species and shared use of 59% of feeding areas. Previous studies on other oystercatcher species may have found intersexual niche partitioning in diet because of highly competitive environments due to high population density or low prey availability. In contrast, the present study in the Virginia barrier islands that found diet overlap between the sexes may be due to a low competitive environment from low breeding densities and sufficient prey abundance. [ABSTRACT FROM AUTHOR]

Male and female Dunlin ( Calidris alpina) exhibit slight plumage and structural differences. Discriminant function analysis based on morphological characteristics can effectively differentiate between sexes in several subspecies of Dunlin. We assessed the level of sexual size dimorphism in a subspecies that breeds in sub-Arctic Canada ( C. a. hudsonia), and used discriminant function analysis to create equations to classify individuals to sex using five body measurements (body mass, head length, culmen length, tarsus length, and flattened wing chord). Females were significantly larger than males for all body measurements. Discriminant function analysis using tarsus length, head length, and body mass correctly classified 87.1% of molecularly sexed females ( n = 31) and 92.6% of males ( n = 27). The classification of an independent sample ( n = 12) resulted in 100.0% correct assignment of sex with 33.3% of individuals falling within the undetermined range. A discriminant function analysis equation is provided for use with non-breeding populations using only structural characteristics with classification accuracies of 83.9% for females and 81.5% for males. The resulting equations from this study have classification accuracies comparable to those equations developed for other Dunlin subspecies and can be used to reliably differentiate sexes of C. a. hudsonia using body measurements collected in the field. [ABSTRACT FROM AUTHOR]

The article focuses on a study on the apparent survival of the American Oystercatcher or Haematopus palliatus on the beaches and in the salt marshes in Virginia. It is said that bird population in beaches has declined while those of birds in salt marshes and shell rakes has risen. The study suggests that birds nesting in salt marsh habitats exhibit 13% greater adult survival than those at coastal beaches. Habitat effects and breeding-site fidelity are cited as factors behind the difference.

The article presents a study about Whimbrels' (Numenius phaeopus) selection of habitat at the vegetation transition area between boreal forest and coastal tundra. The research aimed to establish proof that the wading birds' preferred areas have less shrub/tree cover, and determine the effect of woody vegetation, including other aspects of habitat selection, in their hatching success. Two spatial ranges in Manitoba were studied to gather the needed data.

The article presents a study on foraging habitat quality and behavior of Semipalmated Plovers or Charadrius semipalmatus. Non-breeding plovers followed the foraging sites in southeastern Georgia. Invertebrate density and biomass predicted the foraging rates in pecks/minute and densities in birds/hectare of plovers. Birds did not experience intra-specific competition as shown by the absence of effect of density of foraging birds in their foraging rates at mudflats.