Willow Flycatcher (Empidonax traillii)

2020 ◽  
Author(s):  
James A. Sedgwick
Keyword(s):  
Willow Flycatcher ◽  
Empidonax Traillii

scholarly journals Polygyny and Extra-Pair Paternity in a Population of Southwestern Willow Flycatchers

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 571-578
Author(s):  
Talima Pearson ◽  
Mary J. Whitfield ◽  
Tad C. Theimer ◽  
Paul Keim
Keyword(s):  
Reproductive Success ◽  
Microsatellite Markers ◽  
Mating Strategy ◽  
Male Reproductive Success ◽  
Offspring Survival ◽  
Extra Pair Paternity ◽  
Study Population ◽  
Willow Flycatcher ◽  
Empidonax Traillii ◽  
Disproportionate Number

Abstract Although polygyny can potentially increase male reproductive success, the benefits of this strategy could be offset by losses to extra-pair paternity or reduced offspring survival. We developed microsatellite markers to assess the influence of extra-pair offspring (EPO) on reproductive success and paternity in monogamous and polygynous pairs of the facultatively polygynous Southwestern Willow Flycatcher (Empidonax traillii extimus). Based on genotypes of 140 offspring from 56 clutches over six years, 14% of nestlings in our study population were extra-pair offspring, with 23% of all successful nests containing at least one EPO. We found that polygynous males produced 2.11 ± 0.35 offspring per season, compared to 1.15 ± 0.18 for monogamous males. This increased reproductive success was due primarily to the increased number of nests of polygynous males, as the number of offspring per pair did not differ between monogamous and polygynous males. Twenty of the 140 genotyped nestlings were extra-pair offspring. Sires could be assigned to 16 of these; one polygynous male sired two EPO in one nest, two monogamous males sired eight EPO in two nests, and four nonterritorial males sired six EPO in four nests. Overall, these results indicate that in this population, females of polygynous males did not raise a disproportionate number of EPO as a result of the polygynous mating strategy of their mate, and that both territorial and nonterritorial males sired EPO.

scholarly journals Nestling Sex Ratio in the Southwestern Willow Flycatcher

The Condor ◽  
2002 ◽  
Vol 104 (4) ◽  
pp. 877-881
Author(s):  
Eben H. Paxton ◽  
Mark K. Sogge ◽  
Tracy D. McCarthey ◽  
Paul Keim
Keyword(s):  
Sex Ratio ◽  
Molecular Genetic ◽  
Small Population ◽  
Geographic Isolation ◽  
Breeding Populations ◽  
Population Sizes ◽  
Genetic Techniques ◽  
Willow Flycatcher ◽  
Empidonax Traillii ◽  
Negative Impacts

AbstractUsing molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts.Cociente de Sexos en Polluelos de Empidonax traillii extimusResumen. Utilizando técnicas moleculares determinamos el sexo de 202 polluelos de Empidonax traillii extimus pertenecientes a 95 nidos que fueron muestreados durante un período de cinco años. En general, el cociente de sexos no varió significativamente de 50:50 entre años, ya sea por orden de la nidada o por estrategia de apareamiento (monogamia vs. poligamia). Sin embargo, observamos diferencias significativas entre los cuatro sitios muestreados, en los cuales la razón de sexos estuvo sesgada hacia los machos o las hembras dependiendo del sitio. Dados los pequeños tamaños poblacionales y el aislamiento geográfico de muchas de las poblaciones reproductivas de esta subespecie en peligro, las diferencias en el cociente de sexos pueden tener un impacto negativo a nivel local.

Song but not plumage varies geographically among willow flycatcher Empidonax traillii subspecies

2020 ◽  
Vol 51 (12) ◽  
Author(s):  
Sean M. Mahoney ◽  
Matthew W. Reudink ◽  
Bret Pasch ◽  
Tad C. Theimer
Keyword(s):  
Willow Flycatcher ◽  
Empidonax Traillii

scholarly journals Geographic Variation in the Song of Willow Flycatchers: Differentiation Between Empidonax Traillii Adastus and E. T. Extimus

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 366-379 ◽  
Author(s):  
James A. Sedgwick
Keyword(s):  
New Mexico ◽  
Maximum Amplitude ◽  
High Elevation ◽  
Group Method ◽  
Song Type ◽  
Pair Group ◽  
Upgma Cluster Analysis ◽  
Northern Utah ◽  
Willow Flycatcher ◽  
Empidonax Traillii

AbstractThe vocal signatures of the primary song form (“fitz-bew”) of the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus) and its northern counterpart, E. t. adastus, are distinctive. Songs of the extimus subspecies are longer (total song, note, internote) and frequencies at maximum amplitude are lower than those of adastus. I used vocal evidence to clarify the distributional limits of the Southwestern Willow Flycatcher and that of the geographically adjacent subspecies, E. t. adastus. Unweighted pair-group method using averaging (UPGMA) cluster analysis and canonical discriminant analysis revealed that (1) low elevation, southerly desert populations (Arizona, New Mexico, and southern Utah) have a unique vocal identity corresponding to populations in the range of E. t. extimus; (2) northerly song groups (Oregon, Colorado, and northern Utah) share a different song type corresponding to populations in the range of E. t. adastus; and (3) a departure from vocal and morphological congruence occurs for a population of high-elevation Arizona birds that, although in the currently accepted range of E. t. extimus, sings songs acoustically similar to more northern populations (E. t. adastus). Multiple regression of song distance on latitude and elevation, and a comparison of a matrix of song distances with a matrix of latitude and elevation dissimilarities, demonstrated that song populations sort out by both latitude and elevation: birds with the vocal identity of extimus occur as far north as 37°N if at low elevation, and those acoustically similar to adastus occur as far south as 33.7°N if at high elevation. The vocal background of northern New Mexico birds appears to be intermediate between that of extimus and adastus, suggesting that northern New Mexico is a zone of intermixing and intergradation between the subspecies. Pure forms of E. t. extimus apparently do not occur in Colorado because even the southernmost populations are acoustically similar to more northerly populations of adastus. A low-elevation population in western Colorado, however, stands apart from other adastus populations, suggesting moderate introgression of extimus genes into the adastus gene pool.

Willow flycatcher (Empidonax traillii) surveys in the Colorado River delta: implications for management

2001 ◽  
Vol 49 (1) ◽  
pp. 161-169 ◽  
Author(s):  
Jaqueline Garcı́a-Hernández ◽  
Osvel Hinojosa-Huerta ◽  
Vanda Gerhart ◽  
Yamilett Carrillo-Guerrero ◽  
Edward P. Glenn
Keyword(s):  
Colorado River ◽  
River Delta ◽  
Colorado River Delta ◽  
Willow Flycatcher ◽  
Empidonax Traillii
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