Tag: Dolichonyx oryzivorus

Natural and induced magnetization in the bobolink, dolichonyx oryzivorus (aves: icteridae)

Bobolink (Dolichonyx oryzivorus) Science Article 1 abstract The magnetic characteristics of the heads from 28 bobolinks [Icteridae:Dolichonyx oryzivorus (L.)] were analysed using remanence magnetometers. Thenatural remanent magnetization of 12 freshly preserved heads averaged 3-20xl0~7electromagnetic units (e.m.u.) (le.m.u. = 103Am~’) and was oriented horizontallyfrom side to side. An electromagnet was used to induce magnetization with externalfield […]

Male and Female Reproductive Strategies in the Polygynous Bobolink

Bobolink (Dolichonyx oryzivorus) Science Article 6 abstract Most species of birds are socially monogamous, however approximately 8% of bird species are polygynous. By mating polygynously,females lose paternal care, but might gain access to a superior territory or male. We examined five factors that affect polygyny inbobolinks: territory size, perching sites, predation rate, insect abundance, and […]

Multiple paternity in a territorial passerine: the bobolink

Bobolink (Dolichonyx oryzivorus) Science Article 8 abstract Electrophoretic and behavioral evidence corroborate the conclusion that Bobolink (Dolichonyx oryzivorus) females occasionally copulate with more than one male, whichresults in the insemination of a single clutch of eggs by those males. In 2 of 12 families from which blood samples were obtained from the mother, the putative […]

Factors affecting how male and female bobolinks apportion parental investments

Bobolink (Dolichonyx oryzivorus) Science Article 7 abstract Male and female Bobolinks (Dolichonyx oryzivorus) adjust the amount of time spent brooding and provisioning nestlings at primary nests in light of prevailing weather conditions and food availability. Males brood nestlings less and feed them more (mg/h) when food is scarce, regardless of weather conditions. Primary (i.e., first-mated) […]

Does the avian ophthalmic nerve carry magnetic navigationalinformation?

Bobolink (Dolichonyx oryzivorus) Science Article 3 abstract The bobolink (Dolichonyx oryzivorus) uses the earth’s magnetic field as one source of directional information for its migratory orientation. However, the location and structure of the magnetoreceptors that transduce the magnetic information to the nervous system are unknown. Because treatment with a strong magnetic pulse results in a […]

Photoperiodism and the annual testicular cycle of the bobolink (dolichonyx oryzivorus), a trans equatorial migrant, as compared with two temperate zone migrants

Bobolink (Dolichonyx oryzivorus) Science Article 5 abstract It is now quite generally accepted that seasonal changes in day-length play animportant role in the temporal regulation of several annual cyclic phenomena inmany birds of the northern hemisphere. Best known is the effect of photoperiodson the annual cycle of the testes, but evidence is accumulating that there […]

Spatial responses of bobolinks (dolichonyx oryzivorus)near different types of edges in northern iowa

Bobolink (Dolichonyx oryzivorus) Science Article 2 abstract Habitat edges are well-studied components of fragmented landscapes, yet factorsmediating edge effects remain unclear. We report how different types of edges surroundingpatches may affect spatial distributions of Bobolink (Dolichonyx oryzivorus), a declining, area-sensitive songbird that breeds in grasslands. We expected Bobolinks to be less abundant near edges, and […]

Preliminary Study in whether land management affects dialect formation in Bobolinks

Bobolink (Dolichonyx oryzivorus) Science Article 4 abstract Song dialects occur when individuals share similarity in song phrases at the group level. Most hypotheses regarding formation and maintenance of dialects attempt to explain how females select mates through preferences for local song types (Payne et al. 1981; Baker & Cunningham 1985; Rothstein & Fleischer 1987). Anastasia […]