Which birds participate in mass concentrations of Bramblings Fringilla montifringilla?—Ring recoveries, biometry, age and sex composition Lukas Jenni Original Article Open access 30 July 2021 Pages: 1 - 17
Cross the sea where it is narrowest: migrations of Pacific Swifts (Apus pacificus) between Sakhalin (Russia) and Australia Pavel KtitorovWieland HeimLuke Gibson Original Article 23 July 2021 Pages: 19 - 26
Seasonal differences in migration strategies of Red Kites (Milvus milvus) wintering in Spain Jorge García-MacíaJavier Vidal-MateoVicente Urios Original Article Open access 29 July 2021 Pages: 27 - 36
Migration and non-breeding ecology of the Yellow-breasted Chat Icteria virens Kristen A. MancusoKaren E. HodgesChristine A. Bishop Original Article Open access 15 October 2021 Pages: 37 - 50
Underestimated scale of songbird offshore migration across the south-eastern North Sea during autumn Vera BrustOmmo Hüppop Original Article Open access 13 October 2021 Pages: 51 - 60
Fuel management, stopover duration and potential flight range of pied flycatcher Ficedula hypoleuca staying in South-West France during autumn migration Jean-Marc FourcadePhilippe FontanillesLaurent Demongin Original Article 16 November 2021 Pages: 61 - 70
All-season space use by non-native resident Mandarin Ducks (Aix galericulata) in northeastern Germany Ulrike E. SchlägelWolfgang Mädlow Original Article Open access 20 October 2021 Pages: 71 - 82
Female breeding dispersal to higher quality habitats in a philopatric top predator Andreas OtterbeckAndreas LindénPatrik Byholm Original Article Open access 10 December 2021 Pages: 83 - 92
Contrasting patterns of geographical song variation in two closely related passerine species with a simple song Ivana CzocherováLucia RubáčováTereza Petrusková Original Article 14 August 2021 Pages: 93 - 104
Vocal behavior and microgeographic variation in song types in a Neotropical songbird Juliana Rodríguez-FuentesCarlos Daniel CadenaJorge Enrique Avendaño Original Article 27 September 2021 Pages: 105 - 119
Vocal behaviour of Sclater’s Wrens, a duetting Neotropical songbird: repertoires, dawn chorus variation, and song sharing Marcos Quiroz-OlivaJ. Roberto Sosa-López Original Article 20 October 2021 Pages: 121 - 136
Diet of nestling Barn Swallows in an agroecosystem: insights from fecal DNA barcoding and feather stable isotopes (δ13C, δ15N) Jackson W. KusackGreg W. MitchellKeith A. Hobson Original Article 23 July 2021 Pages: 137 - 150
Essential amino acid requirements of granivorous and omnivorous songbirds and the provision of natural foods Lillie A. LangloisScott R. McWilliams Original Article 26 July 2021 Pages: 151 - 163
Changing places: spatial ecology and social interactions of female and male Montagu’s Harrier (Circus pygargus) in the Spanish Extremadura Brigitte Berger-GeigerGeorg HeineC. Giovanni Galizia Original Article Open access 03 August 2021 Pages: 165 - 179
Head and body orientation of the White Stork Ciconia ciconia during incubation: effect of wind, apex predators and power lines Adam ZbyrytŁukasz JankowiakPiotr Tryjanowski Original Article Open access 28 July 2021 Pages: 181 - 189
Chemical analysis reveals sex differences in the preen gland secretion of breeding Blue Tits Barbara A. CaspersReinaldo MarfullPeter Korsten Original Article Open access 11 August 2021 Pages: 191 - 198
Differences in transcription regulation of diurnal metabolic support to physiologically contrasting seasonal life-history states in migratory songbirds Aakansha SharmaSubhajit DasVinod Kumar Original Article 30 August 2021 Pages: 199 - 212
Body composition of American Woodcock during fall staging: a validation of the non-invasive deuterium dilution method Clayton L. GrahamScott R. McWilliams Original Article 26 September 2021 Pages: 213 - 222
Linking environmental indicators to blood, feather and claw δ18O in the Saffron Finch (Sicalis flaveola) in the central Brazilian savannas Fábio José Viana CostaKeith A. HobsonGabriela Bielefeld Nardoto Original Article 19 November 2021 Pages: 223 - 234
Measuring circulating triglycerides in free-living birds: evaluation of a field-usable point-of-care analyzer for American woodcock Christopher M. RoelandtAmber M. RothJill C. Witt Original Article 25 November 2021 Pages: 235 - 241
Strong evidence supporting a relationship between colour pattern and apparent survival in common crossbills Blanca Fernández-EslavaDaniel AlonsoJuan Arizaga Original Article Open access 23 September 2021 Pages: 243 - 249
Influence of age and body condition on breeding performance in Common Kingfisher Alcedo atthis M. CepkováM. BalážováL. Rubáčová Original Article 13 August 2021 Pages: 251 - 261
Effects of elevated nest box temperature on incubation behaviour and offspring fitness-related traits in the Collared Flycatcher Ficedula albicollis Aneta ArctRafał MartykaLars Gustafsson Original Article Open access 09 December 2021 Pages: 263 - 272
No evidence that declining Whinchat Saxicola rubetra are currently limited by the availability of apparently suitable breeding habitat within the UK uplands Andrew J. StanburyIrena TománkováDavid J. T. Douglas Original Article 02 September 2021 Pages: 273 - 283
Swallows nesting on buildings showed positive population trends except when having deeply forked tails Masaru HasegawaEmi Arai Original Article 05 October 2021 Pages: 285 - 289
Genetic diversity and differentiation of the widespread migratory Demoiselle Crane, Grus virgo, on the northern edge of the species’ distribution Elena A. MudrikElena I. IlyashenkoDmitry V. Politov Original Article 06 August 2021 Pages: 291 - 299
Characterization of an extinct seabird colony on the island of Santa Luzia (Cabo Verde) and its potential for future recolonizations Maria AlhoJosé Pedro GranadeiroPaulo Catry Original Article 18 August 2021 Pages: 301 - 313
Cranium of an Eocene/Oligocene pheasant-sized galliform bird from western North America, with the description of a vascular autapomorphy of the Galliformes Gerald MayrJames L. GoedertRenate Rabenstein Original Article Open access 15 October 2021 Pages: 315 - 326
Diversification across the Isthmus of Tehuantepec explains the phylogeographic arrangement of the widespread bright-rumped Attila (Attila spadiceus; Tyrannidae) and reveals the existence of two major lineages Patrícia MendonçaCleyssian DiasPéricles Sena do Rêgo Short Communication 02 September 2021 Pages: 327 - 332
Trichomonas gallinae infections in the naïve host Montifringilla nivalis subsp. nivalis Sebastian DirrenStéphanie BorelFränzi Korner-Nievergelt Short Communication Open access 08 November 2021 Pages: 333 - 337
