Fall migration of radio-tagged Broad-winged Hawks (Buteo platypterus) in California

Capitolo, Phillip J.; Jesus, Lynn J.; Harper, Alan; Fish, Allen M.; Hull, Angus C.

doi:10.1676/1559-4491-132.1.15

Cited by 3 publications

(2 citation statements)

References 12 publications

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“…One explanation is that eBird reports for Common Redpoll in autumn 2016 may have been under-reported in various regions along the migration corridor (Kosmala et al 2016); however, raptors migrating along the Pacific Coast of western North America reportedly travel upwards of 265 km/day (e.g. Broad-winged Hawk Buteo platypterus; Capitolo et al 2020). Our results indicate that prey DNA may be detectable on raptors for several days en route, despite DNA degradation and removal due to individual behaviour, UV degradation or precipitation.…”

Section: Discussionmentioning

confidence: 99%

Falcon fuel: metabarcoding reveals songbird prey species in the diet of juvenile Merlins (Falco columbarius) migrating along the Pacific Coast of western North America

Bourbour

Aylward

Tyson

et al. 2021

Ibis

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During autumn migration, bird-eating raptors are thought to rely on flocks of migrant songbirds (Passeriformes) as a critical resource to fuel the energetic demands of longdistance migration. However, this hypothesis has been challenging to investigate, and the foraging ecology during migration of most migrant raptors remains unexplored. To address these knowledge gaps, our objective was to document the diet of a bird-eating falcon on active migration. We swabbed visible and trace prey residues from the exterior surface of beaks and talons of migrant juvenile Merlins Falco columbarius in the autumn of 2015 and 2016 at a raptor migration monitoring station positioned on the Pacific Coast of western North America. We used a DNA metabarcoding approach and detected the presence of 40 distinct prey species derived from 210 individual prey species detections on 63 of the 72 (87.5%) migrant juvenile Merlins sampled. We detected an average of 3.3 AE 1.6 prey species on individual Merlins. We found that juvenile males selected smaller prey on average compared with juvenile females. Of the prey species detected, over 80% were migratory songbird species within the Pacific Flyway. In 2015, we detected a greater proportion of irruptive migrants in juvenile Merlin diet compared with 2016. In 2016, we found that the proportion of annual migrants consumed by Merlins corresponded to the timing of peak annual songbird migration in the Pacific Flyway. This study represents one of the first detailed descriptions of songbird prey species consumed by a migrating raptor and supports the hypothesis that migrating juvenile Merlins rely on migrant songbirds to support the energetic demands of migration.

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Section: Discussionmentioning

confidence: 99%

Falcon fuel: metabarcoding reveals songbird prey species in the diet of juvenile Merlins (Falco columbarius) migrating along the Pacific Coast of western North America

Bourbour

Aylward

Tyson

et al. 2021

Ibis

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“…Capitolo et al (2020) tracked migrating Broad-winged Hawks (Buteo platypterus), where daily straight-line migration distances were between 110 and 265 km. If Hook-billed Kites migrate at approximately the same rate, then kites in Veracruz would reach Belize in 4-10 d, the estimated lag time between sites based on distance.…”

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confidence: 99%

Intratropical migration of the Hook-billed Kite ( Chondrohierax uncinatus ) in Middle America

Phillips¹,

Wolf²,

Bourbour³

et al. 2023

JFO

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The Hook-billed Kite (Chondrohierax uncinatus) is a specialized and secretive Neotropical raptor that has received little research attention. Despite scattered records of Hook-billed Kite movements, this species was long thought to be non-migratory. We studied the southbound autumn migration of Hook-billed Kites in Veracruz, Mexico, and Belize and investigated whether environmental conditions on their breeding grounds influenced migration. We collected migration count data over 8 years (2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020) in Belize and 25 years (1995-2019) in Veracruz. In Belize, we recorded 39,928 Hook-billed Kites on their southbound autumn migration during a total of 3093.1 count hours, with an autumn seasonal mean (±SE) count of 4991 ± 1083 kites/year, with flocks consisting of up to 200 individuals. In comparison, during a total of 42,531 count hours at two count sites in Veracruz, we recorded 3870 Hook-billed Kites with a seasonal mean (±SE) count of 154.8 ± 12.1 kites/year. Most kites in Veracruz migrated as single individuals or groups of < 4 birds and the largest flock ever recorded had 12 individuals. The mean 95% seasonal passage window of Hook-billed Kites in Belize lasted 44.9 ± 2.5 d (N = 8 years) from 26 October to 9 December compared to an earlier passage from 13 September-11 November in Veracruz (N = 25 years). Precipitation on the breeding grounds had no influence on the timing or magnitude of the kite migration through Belize; whereas, in Veracruz, migration timing occurred later as precipitation north of the count site increased. Notably, age, sex, and color morph classes migrated in mixed flocks; therefore, we detected no signs of differential migration, which is uncommon among raptors. Our study describes, for the first time, the largest known southbound autumn migration of Hook-billed Kites. Working to understand the life histories of tropical raptors provides critical ecological information, which can aid in identifying potential threats, conservation needs, and population statuses.RESUMEN. Chonrrohierax uncinatus es una ave rapaz Neotropical especializada y sigilosa que ha recibido poca atención en la investigación. A pesar de los registros dispersos de los movimientos de C. uncinatus, por largo tiempo se ha pensado que esta especie no es migratoria. Estudiamos la migración de otoño hacia el sur de C. unicnatus en Veracruz, México y Belice e investigamos si las condiciones ambientales en la zona de reproducción influencian la migración. Colectamos datos de conteos migratorios durante 8 años (2013-2020) en Belice y 25 años en Veracruz. En Belice registramos 39,928 individuos durante su migración de otoño hacia el sur durante un total de 3093.1 horas de conteo, con un promedio de los conteos de otoño estacionales (±SE) de 4991 ± 1083 aves/ año, con bandadas compuestas por hasta 200 individuos. En comparación, durante un total de 42,531 horas de conteo en dos sitios en Veracruz, registramos 3870 C. uncinatus con un promedio en los conteos estacionales (±SE) de 154.8 ± 12.1 ave...

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Age-Class Difference in Wintering Distribution of Broad-Winged Hawks

Heveran

Goodrich

Barber

2022

Journal of Raptor Research

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The Broad-winged Hawk (Buteo platypterus) is one of the most easily observed North American raptors during migration, yet little is known about its distribution during the nonbreeding season. To better understand the winter distribution of Broad-winged Hawks by age, we compiled 2164 Broad-winged Hawk sightings with age data and 25,797 sightings without age data reported to eBird during the nonbreeding period from 2000–2020. The mean latitude of adult birds was significantly farther south than the mean latitude of immatures, with broad overlap in the distribution of both age classes from the United States through South America. The distribution of birds that were not aged overlapped the distribution of both age classes. A higher proportion of immatures was observed in the United States through Central America, with a mean latitude of 15.69°N, whereas adults were concentrated in Central and South America (with a mean latitude of 9.93°N). When only birds wintering south of the United States were analyzed, immatures were still found farther north than adults, although the latitude difference was less. The winter age class distribution for Broad-winged Hawks could result from short-stopping behavior occurring more often in immatures than adults. Further research is needed to understand how geographic, sex, and age class groups may differ in winter distributions and the implications of these patterns. Citizen science data from eBird proved useful in examining broad-scale patterns in Broad-winged Hawk winter distribution and is a valuable resource to scientists evaluating avian distributions.

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Fall migration of radio-tagged Broad-winged Hawks (Buteo platypterus) in California

Cited by 3 publications

References 12 publications

Falcon fuel: metabarcoding reveals songbird prey species in the diet of juvenile Merlins (Falco columbarius) migrating along the Pacific Coast of western North America

Falcon fuel: metabarcoding reveals songbird prey species in the diet of juvenile Merlins (Falco columbarius) migrating along the Pacific Coast of western North America

Intratropical migration of the Hook-billed Kite ( Chondrohierax uncinatus ) in Middle America

Age-Class Difference in Wintering Distribution of Broad-Winged Hawks

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