DOCSLIB.ORG

Willow Flycatcher (Empidonax Traillii) Robert B

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Willow Flycatcher (Empidonax Traillii) Robert B Willow Flycatcher (Empidonax traillii) Robert B. Payne (Click to view a comparison of Atlas I to II) © Jerry Jourdan Distribution Willow Flycatchers are widespread in late Willow Flycatchers are common summer spring and summer in northeastern North residents in southern Michigan and are sparsely America and in much of the northern plains and distributed in northern Michigan. In Michigan in the west. The species was known in earlier they are generally more southern than Alder records in Michigan as "Alder Flycatcher" and Flycatchers, but the two species overlap in their "Traill's Flycatcher" (Barrows 1912, Wood breeding range throughout the SLP and NLP. 1951), and the early records did not distinguish Willow Flycatchers live in a variety of habitats between two distinct species, Willow Flycatcher of upland brush and lowland swamps, in and Alder Flycatcher. Only about 80-90% of overgrown uplands, dry marsh with unplowed birds of the two species can be distinguished in brushy grassy fields, old pasture land and morphology, but their behavior is distinct. thickets, shrubs along the edges of streams, and Willow Flycatchers give two song themes in wet thickets of willow, alder and buckthorn. In irregular alternation, "FITZ-bew!" and "FEE- southern Michigan most birds arrive from 7 to BEOO!" As they sing, Willow Flycatchers toss 17 May. The birds remain on their breeding back their heads further for the first note (in grounds from May through August and some "FITZ-bew!") or the same distance for the first birds are seen there in early September and second notes (in "FEE-BEOO!"). The (Walkinshaw 1966). second song theme is sometimes mistaken for the "knee-DEEP!" single song theme of Alder Breeding Biology Flycatchers. The call of the Willow Flycatcher In Michigan, as many as 45 nesting pairs of is a liquid "whit" (Stein 1958, 1963). Willow Willow Flycatchers have been observed locally Flycatchers are long-distance migrants and in 100 ha in a breeding population (Berger winter in the Pacific lowlands in southwestern 1957). The average territory size in southern Mexico, in the Caribbean and Pacific lowlands Michigan is 0.84 ha Birds build their nests from of Central America and in northern Colombia. early though late June; some active nests are They do not sing in winter; their winter range in found into mid-July and young are fledged as the Neotropics has been determined in part by late as the first half of August. The late nests are their response to a playback of their songs in of birds that failed an earlier breeding attempt Central America (Gorski 1969, Sedgwick 2000). and no second nesting attempts were found after birds had reared successfully an earlier brood © 2011 Kalamazoo Nature Center Willow Flycatcher (Empidonax traillii) Robert B. Payne (Walkinshaw 1966). Their nests are often built northern Wisconsin they have been reported in in shrubs and small trees of dogwood, hawthorn, three counties bordering the UP (Cutright et al. rose, honeysuckle, alder and willows. Nests are 2006), although not in the counties bordering open cups of grass and large amounts of cotton- Gogebic Co. where Willow Flycatchers were like material or shredded fiber and feathers, mapped in MBBA I and MBBA II. In Ontario much like nests of Yellow Warblers and they occur in abundance as far north as the American Goldfinch; nests are compact on the southern Georgian Bay region, about the same underside and without a trailing streamer and in latitude as in the NLP of Michigan and on this way they differ from nests of the Alder Manitoulin Island in Lake Huron east of the UP, Flycatcher. The eggs usually differ from eggs of and their distribution has moved northward onto Alder Flycatcher and are a deeper buff color the Southern Shield region (Cadman et al. with larger and more diffuse spots (Fargo 1928, 2007). In Michigan during MBBA I, the Stein 1958, 1963). The nests often are brood- proportion of surveyed townships where the parasitized by Brown-headed Cowbirds (Berger flycatchers were detected was 80% in the SLP, & Parmelee 1952, Berger 1957, 1967, 27% in the NLP and 3% in the UP; and in Walkinshaw 1966). Adult flycatchers return to MBBA II their numbers were nearly the same the same area from year to year: 41% of adult (77%, 21% and 3%). In the Breeding Bird males banded in one year were seen again in the Surveys from 1996 to 2006, Willow Flycatchers next year, all on their old territory, one bird have undergone a small but significant decrease returning each year into its fifth year. Only 23% in numbers both in Michigan and throughout the of females returned to their old territory; the range of the species. In the combined data for missing numbers were likely both birds that did both Alder and Willow Flycatchers, there has not survive and birds that returned and settled in been no significant change in numbers in a new area. A few young flycatchers return to Michigan or throughout North America (Sauer their natal area in a later breeding season: two et al. 2008). In contrast to Michigan, Ontario were found at a distance 500 and 1600 m from and elsewhere in the Lower Great Lakes, the the territory where they were born (Walkinshaw numbers of flycatchers in Quebec, New York, 1966). the Appalachian Mountains, the Atlantic Northern Forest, New England and the Mid Abundance and Population Trends Atlantic Coast appear to have increased in (Click to view trends from the BBS) recent years (Cadman et al. 2007, McGowan & The atlas surveys show that Willow Flycatchers Corwin 2008, Sauer et al. 2008). are widespread in the SLP, scattered in the NLP, and sparsely distributed in the UP. Earlier than Conservation Needs the 1960s the Willow Flycatcher and Alder No conservation concerns are evident. Flycatcher were not recognized as two distinct species, so it is not possible to compare the distribution of the two in the early 1900s. In the past few decades there has been no clear evidence of an expansion of the range of Willow Flycatcher into northern Michigan. In the northernmost NLP locality (Dingman's Marsh, Cheboygan Co.) where Willow Flycatcher was reported in both MBBA I and MBBA II, their songs were tape recorded in the 1970s. In the UP nearly all of the few reports of Willow Flycatcher are along the southern border. In © 2011 Kalamazoo Nature Center Willow Flycatcher (Empidonax traillii) Robert B. Payne Literature Citations Kroodsma, D.E. 1984. Songs of the Alder Berger, A.J. 1957. Population density of Alder Flycatcher (Empidonax alnorum) and Flycatchers and Common Goldfinches in Willow Flycatcher (Empidonax traillii) are Crataegus habitats of southeastern innate. Auk 101: 13-24. Michigan. Wilson Bulletin 69: 317-322. Lovell, S.F. & M.R. Lein. 2004a. Song variation Berger, A.J. 1967. Traill's Flycatcher in in a population of Alder Flycatcher. Journal Washtenaw County, Michigan. Jack-Pine of Field Ornithology 75: 146-151. Warbler 45: 117-123. Lovell, S.F. & M.R. Lein. 2004b. Neighbor- Berger, A.J. & D.F. Parmelee. 1952. The Alder stranger discrimination by song in a Flycatcher in Washtenaw County, Michigan: suboscine bird, the Alder Flycatcher. breeding distribution and brood parasitism. Behavioral Ecology 15: 799-804. Wilson Bulletin 64: 33-38. Lovell, S.F. & M.R. Lein. 2005. Individual Binford, L.C. 2006. Birds of the Keweenaw recognition of neighbors by song in a Peninsula, Michigan. Miscellaneous suboscine bird, the Alder Flycatcher Publications, Museum of Zoology, Empidonax alnorum. Behavioral Ecology University of Michigan, no. 195. and Sociobiology 57: 623-630. Cadman, M.D., D.A. Sutherland, G.G. Beck, D. McGowan, K.J. & K. Corwin, eds. 2008. The Lepage & A.R. Courtier, eds. 2007. Atlas of Second Atlas of Breeding Birds in New York the Breeding Birds of Ontario, 2001-2005. State. Cornell University Press, Ithaca, NY. Bird Studies Canada, Port Rowan, Ontario. Sauer, J.R., J.E. Hines & J. Fallon. 2008. The Cutright, N.J., B.R. Harriman and R.W. Howe. North American Breeding Bird Survey, 2006. Atlas of the Breeding Birds of Results and Analysis 1966 - 2007. Version Wisconsin. Wisconsin Society for 5.15.2008. USGS Patuxent Wildlife Ornithology, Waukesha. Research Center, Laurel, MD. Dunn, J.L. and J. Alderfer, eds. 2006. National Sedgwick, J.A. 2000. Willow Flycatcher Geographic Field Guide to the Birds of (Empidonax traillii). In The Birds of North North America, fifth edition. National America, No. 533. Geographic Society, Washington, D. C. http://bna.birds.cornell.edu.bnaproxy.birds.c Fargo, W.G. 1928. Traill's Flycatcher in ornell.edu/bna/species/533. southern Michigan. Wilson Bulletin 40: 218- Stein, R.C. 1958. The behavioral, ecological and 221. morphological characteristics of two Gorski, L.J. 1969. Traill's Flycatcher of the populations of the Alder Flycatcher, "fitz-bew" songform wintering in Panama. Empidonax traillii (Audubon). New York Auk 86: 745-747. State Museum and Science Services Bulletin Gorski, L.J. 1971. Traill's Flycatcher of the "fee- 371: 1-63. bee-o" songform wintering in Peru. Auk 88: Stein, R.C. 1963. Isolating mechanisms between 429-431. populations of Traill’s Flycatchers. Hussell, D.J.T. 1991. Spring migrations of Proceedings of the American Philosophical Alder and Willow Flycatchers in southern Society 107: 21-50. Ontario. Journal of Field Ornithology 62: Walkinshaw, L.H. 1966. Summer biology of 69–77. Traill's Flycatcher. Wilson Bulletin 78: 31- Johnson, N.K. & C. Cicero. 2002. The role of 46. ecological diversification in sibling speciation of Empidonax flycatchers (Tyrannidae): multigene evidence from mtDNA. Molecular Ecology 11: 2065-2081. © 2011 Kalamazoo Nature Center .
Load more

Recommended publications
  • Final Recovery Plan Southwestern Willow Flycatcher (Empidonax Traillii Extimus)
    Final Recovery Plan Southwestern Willow Flycatcher (Empidonax traillii extimus) August 2002 Prepared By Southwestern Willow Flycatcher Recovery Team Technical Subgroup For Region 2 U.S. Fish and Wildlife Service Albuquerque, New Mexico 87103 Approved: Date: Disclaimer Recovery Plans delineate reasonable actions that are believed to be required to recover and/or protect listed species. Plans are published by the U.S. Fish and Wildlife Service, sometimes prepared with the assistance of recovery teams, contractors, State agencies, and others. Objectives will be attained and any necessary funds made available subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. Recovery plans do not necessarily represent the views nor the official positions or approval of any individuals or agencies involved in the plan formulation, other than the U.S. Fish and Wildlife Service. They represent the official position of the U.S. Fish and Wildlife Service only after they have been signed by the Regional Director or Director as approved. Approved Recovery plans are subject to modification as dictated by new findings, changes in species status, and the completion of recovery tasks. Some of the techniques outlined for recovery efforts in this plan are completely new regarding this subspecies. Therefore, the cost and time estimates are approximations. Citations This document should be cited as follows: U.S. Fish and Wildlife Service. 2002. Southwestern Willow Flycatcher Recovery Plan. Albuquerque, New Mexico. i-ix + 210 pp., Appendices A-O Additional copies may be purchased from: Fish and Wildlife Service Reference Service 5430 Governor Lane, Suite 110 Bethesda, Maryland 20814 301/492-6403 or 1-800-582-3421 i This Recovery Plan was prepared by the Southwestern Willow Flycatcher Recovery Team, Technical Subgroup: Deborah M.
    [Show full text]
  • A Natural History Summary and Survey Protocol for the Southwestern Willow Flycatcher
    Prepared in cooperation with the Bureau of Reclamation and the U.S. Fish and Wildlife Service A Natural History Summary and Survey Protocol for the Southwestern Willow Flycatcher Chapter 10 of Section A, Biological Science Book 2, Collection of Environmental Data Techniques and Methods 2A-10 U.S. Department of the Interior U.S. Geological Survey Cover: Southwestern Willow Flycatcher. Photograph taken by Susan Sferra, U.S. Fish and Wildlife Service. A Natural History Summary and Survey Protocol for the Southwestern Willow Flycatcher By Mark K. Sogge, U.S. Geological Survey; Darrell Ahlers, Bureau of Reclamation; and Susan J. Sferra, U.S. Fish and Wildlife Service Chapter 10 of Section A, Biological Science Book 2, Collection of Environmental Data Prepared in cooperation with the Bureau of Reclamation and the U.S. Fish and Wildlife Service Techniques and Methods 2A-10 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2010 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S.
    [Show full text]
  • Willow Flycatcher Empidonax Traillii
    Wyoming Species Account Willow Flycatcher Empidonax traillii REGULATORY STATUS USFWS: Migratory Bird USFS R2: No special status USFS R4: No special status Wyoming BLM: No special status State of Wyoming: Protected Bird CONSERVATION RANKS USFWS: Bird of Conservation Concern WGFD: NSS3 (Bb), Tier III WYNDD: G5, S5 Wyoming Contribution: LOW IUCN: Least Concern PIF Continental Concern Score: 10 STATUS AND RANK COMMENTS Willow Flycatcher (Empidonax traillii) has no additional regulatory status or conservation rank considerations beyond those listed above. Southwestern Willow Flycatcher (E. t. extimus) is designated as Endangered under the Endangered Species Act, but this subspecies is not found in Wyoming 1. NATURAL HISTORY Taxonomy: There are 4 or 5 recognize subspecies of Willow Flycatcher 2, 3. E. t. adastus and possibly E. t. campestris occur in Wyoming 4; however, some authorities do not recognize the campestris subspecies and include those individuals with the traillii subspecies 2. Description: Identification of the Empidonax genus of flycatchers to species is not always possible in the field. In Wyoming, identification of Willow Flycatcher is possible based on vocalization. Willow Flycatcher is a small flycatcher, 13 to 17 cm long. Males, females, and juvenile birds are identical in appearance, and the plumage is the same year-round 2, 5. Willow Flycatcher differs from other Empidonax flycatchers by having plumage that is browner overall and an eye-ring that is very reduced or absent 5. The species’ lower mandible is dull yellow, and the upper mandible is black. The feet are brownish-black to black 6. The most definitive way to identify Willow Flycatcher is by song.
    [Show full text]
  • A Willow Flycatcher Survey Protocol for California
    A Willow Flycatcher Survey Protocol for California May 29, 2003 Helen L. Bombay, Teresa M. Benson, Brad E. Valentine, Rosemary A. Stefani TABLE OF CONTENTS Willow Flycatcher Survey Protocol.............................................................. 1 Background.................................................................................................... 1 I. Objectives.................................................................................................... 2 II. Timing and Number of Visits...................................................................... 3 A. Survey Period 1..................................................................................... 5 B. Survey Period 2..................................................................................... 6 C. Survey Period 3..................................................................................... 6 D. Follow-up Visits.................................................................................... 7 III. Survey Coverage and Spacing................................................................... 9 IV. Survey Methods........................................................................................ 10 A. General Guidelines................................................................................ 10 B. Specific Survey Guidelines..................................................................... 11 V. Recording Additional Information.............................................................. 14 A. Looking for and recording
    [Show full text]
  • Tamarisk Beetle (Diorhabda Spp.) in the Colorado River Basin: Synthesis of an Expert Panel Forum Benjamin R
    Scientific and Technical Report No. 1 JANUARY 2016 Tamarisk beetle (Diorhabda spp.) in the Colorado River basin: synthesis of an expert panel forum Benjamin R. Bloodworth1, Patrick B. Shafroth2, Anna A. Sher 3, Rebecca B. Manners4, Daniel W. Bean5, Matthew J. Johnson6, and Osvel Hinojosa-Huerta7 1Tamarisk Coalition, Grand Junction, CO 2U.S. Geological Survey, Fort Collins, CO 3University of Denver, Denver, CO 4University of Montana, Missoula, MT 5Colorado Dept. of Agriculture, Palisade Insectary, Palisade, CO 6Colorado Plateau Research Station, Northern Arizona University, Flagstaff, AZ 970.248.1968 7Pronatura Noroeste, La Paz, Mexico 1100 North Avenue Grand Junction, CO 81501-3122 coloradomesa.edu/water-center © 2016 COLORADO MESA UNIVERSITY 1 Tamarisk Beetle in the Colorado River Basin Contents Acknowledgements ............................................................ 2 List of Figures Executive Summary Executive Summary ............................................................. 3 Figure 1 — Close-up of an adult tamarisk beetle In 2001, the U.S. Department of Agriculture approved the release of a biological control agent, the tamarisk beetle (Diorhabda Introduction ......................................................................... 4 (Diorhabda spp.). (Photo by Ed Kosmicki). .......................... 3 spp.), to naturally control tamarisk populations and provide a less costly, and potentially more effective, means of removal compared with mechanical and chemical methods. The invasive plant tamarisk (Tamarix spp.; saltcedar)
    [Show full text]
  • Final Recovery Plan Southwestern Willow Flycatcher (Empidonax Traillii Extimus)
    Final Recovery Plan Southwestern Willow Flycatcher (Empidonax traillii extimus) August 2002 Prepared By Southwestern Willow Flycatcher Recovery Team Technical Subgroup For Region 2 U.S. Fish and Wildlife Service Albuquerque, New Mexico 87103 Approved: Date: 018085 Disclaimer Recovery Plans delineate reasonable actions that are believed to be required to recover and/or protect listed species. Plans are published by the U.S. Fish and Wildlife Service, sometimes prepared with the assistance of recovery teams, contractors, State agencies, and others. Objectives will be attained and any necessary funds made available subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. Recovery plans do not necessarily represent the views nor the official positions or approval of any individuals or agencies involved in the plan formulation, other than the U.S. Fish and Wildlife Service. They represent the official position of the U.S. Fish and Wildlife Service only after they have been signed by the Regional Director or Director as approved. Approved Recovery plans are subject to modification as dictated by new findings, changes in species status, and the completion of recovery tasks. Some of the techniques outlined for recovery efforts in this plan are completely new regarding this subspecies. Therefore, the cost and time estimates are approximations. Citations This document should be cited as follows: U.S. Fish and Wildlife Service. 2002. Southwestern Willow Flycatcher Recovery Plan. Albuquerque, New Mexico. i-ix + 210 pp., Appendices A-O Additional copies may be purchased from: Fish and Wildlife Service Reference Service 5430 Governor Lane, Suite 110 Bethesda, Maryland 20814 301/492-6403 or 1-800-582-3421 i 018086 This Recovery Plan was prepared by the Southwestern Willow Flycatcher Recovery Team, Technical Subgroup: Deborah M.
    [Show full text]
  • Southwestern Willow Flycatcher Arizona Ecological Services Field Office
    U.S. Fish & Wildlife Service Southwestern Willow Flycatcher Arizona Ecological Services Field Office Southwestern Willow Flycatcher When imagining wondrous arrays of colorful birds, one usually pictures the tropics. However, southwestern riparian habitats, the lush ribbons of vegetation running along our streams and rivers, contain the highest density and diversity of bird species outside tropical rain forests. Sadly, only a fraction of these desert oases remain unchanged in the United States. As this habitat continues to decline, so too do the birds in our southwest skies. One bird in immediate danger is the southwestern willow flycatcher. This subspecies of the willow flycatcher is an olive-gray bird with a white throat and yellow-gray rump that measures Southwestern Willow Flycatcher about 5¾ inches in length. It can be Flood control projects have distinguished from other subspecies by USGS Photograph inadvertently depleted the cottonwood its song, a sneezy fitza-bew, its call, a The flycatcher is a late spring breeder and willow trees the flycatcher uses for repeated “whit,” and by where it lives: nesting. These trees – a vital, defining widely scattered riparian habitats in the seen and heard in riparian forests by part of riparian ecosystems – need desert Southwest. mid-May. Its nest, a tiny cup about 1¾ inches deep, is made of compact fiber, periodic flooding to reproduce. Flood control efforts have altered this natural The flycatcher reminds observers of a bark, and grass about three to 15 feet cycle in many areas and also made it sentinel constantly at attention, whose above the ground in trees and thickets. The rim is lined with feathers and the possible for non-native species to move flitty wing movements resemble salutes into streamside habitats.
    [Show full text]
  • Tamarisk Biocontrol Using Tamarisk Beetles: Potential Consequences for Riparian Birds in the Southwestern United States Eben H
    The Condor 113(2):255–265 ¡The Cooper Ornithological Society 2011 TAMARISK BIOCONTROL USING TAMARISK BEETLES: POTENTIAL CONSEQUENCES FOR RIPARIAN BIRDS IN THE SOUTHWESTERN UNITED STATES EBEN H. PAXTON1,4, TAD C. THEIMER2, AND MARK K. SOGGE3 1U.S. Geological Survey, Pacific Islands Ecological Research Center, Hawaii National Park, HI 96718 2Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011 3U.S. Geological Survey, Flagstaff, AZ 86001 Abstract. The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradi- cate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian wood- lands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains un- known. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a well- studied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the po- tential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, de- pending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mor- tality.
    [Show full text]
  • Southwestern Willow Flycatcher (Empidonax Traillii Extimus) Overview
    Southwestern Willow Flycatcher (Empidonax traillii extimus) Overview Predicted Impacts Habitat Change 2030 48-50% Loss 2060 54-62% Loss 2090 62-71% Loss Adaptive capacity Very Low Fire Response Negative Status: The Southwestern willow flycatcher has been on the federal endangered species list since 1995. Range and Habitat: The Southwestern Willow flycatcher inhabits riparian areas in the southwestern U.S. (Figure 1). It winters in southern Mexico, Central America and northern South America (Sedgwick 2000). In the Middle Rio Grande, the Southwestern willow flycatcher migrates through willow, cottonwood and saltcedar stands (Hunter 1988; Cartron et al. 2008). It is common in New Mexico during migration in the spring and fall, but also breeds in a few areas along the Middle Rio Grande. This species is associated with dense shrubby and wet habitats and typically nests in flooded areas with willow dominated habitat (Sedgwick 2000). Generally, the Southwestern willow flycatcher does not occupy areas dominated by exotics (Skoggs and Marshall 2000), but can successfully nest in saltcedar-dominated habitats (Skoggs et al. 2006). Figure 1. Distribution of Empidonax traillii subspecies. From Sogge et al. 2010, USGS. Southwestern Willow Flycatcher (Empidonax traillii extimus) Climate Impacts and Adaptive Capacity Adaptive capacity score = 2.5 (very low) There are a number of indications for potential negative impacts for the flycatcher under changing climate (Table 1). The Southwestern willow flycatcher uses shrubs and small trees for nesting substrates. Increased shrub cover is associated with reproductive success of the Southwestern willow flycatcher (Bombay et al. 2003). Additionally, willow flycatchers will not nest if water is not flowing (Johnson et al.
    [Show full text]
  • Feeding-Time Minimization and the Territorial Behavior of the Willow Flycatcher (Empidonax Traillii)
    FEEDING-TIME MINIMIZATION AND THE TERRITORIAL BEHAVIOR OF THE WILLOW FLYCATCHER (EMPIDONAX TRAILLII) DAVID R. C. PRESCOTT AND ALEX L. A. MIDDLETON Departmentof Zoology,College of BiologicalScience, Universityof Guelph,Guelph, Ontario N1G 2W1, Canada ABSTRACT.--Westudied breeding male Willow Flycatchers(Empidonax traillii) to testa model of optimalterritorial behavior for feeding-timeminimizers proposed by Hixon (1980).Specific predictionswere that feeding time, defense time, and territory size should decreasewith increasingfood availability and increasewith increasedpressure from both conspecificand heterospecificcompetitors. The constantreproductive output of 4 and 3 eggsfor firstand secondclutches, respectively, and the large componentof uncommitted(sitting) time (62.6 + 3.2%) over the breeding seasonconfirmed that the Willow Flycatcherconformed to a time-minimizationstrategy. Data analyzedover three stagesof the breedingcycle, and over all stages,however, showed that only 5 of the 36 possiblerelationships were significantas predicted by the model.In general, food availability and competitorpressure were not important influenceson the territorial behavior of thesebirds. Variations in territory size could not be attributed to constraintson feeding time, but correlatedclosely with the energeticrequirements of all birds occupying the territory. We believethat breedinginsectivorous passerines, including Willow Flycatchers,maintain a large componentof uncommittedtime, as well as a larger than necessaryterritory, to minimize the impact of
    [Show full text]
  • Status, Ecology, and Conservation of the Southwestern Willow Flycatcher
    Mark K. Sogge Chapter 6: Breeding Season Ecology The willow flycatcher (Empidonax traillii) breeds and includes comparisons with other populations across much of the conterminous United States and in and subspecies. portions of extreme southern Canada. As might be expected in such a wide-ranging species, willow fly- catchers in different portions of the range exhibit Breeding Range and Taxonomy _____ differences in appearance, song, and ecological char- The willow flycatcher is one of 11 Empidonax fly- acteristics. The intent of this chapter is to provide catchers that breed in North America. Although the information on the breeding-season ecology of the Empidonax flycatchers are considered a very difficult southwestern subspecies, E.t. extimus. However, most group to identify by sight alone, each has unique ecological studies to date have dealt with other willow morphological features, vocalizations, habitats, be- flycatcher subspecies. Relatively few studies have haviors, and/or other traits that have allowed taxono- been published on E.t. extimus, and much of what is mists and biologists to characterize each species. The currently known is presented in unpublished litera- willow flycatcher differs from most other Empidonax ture (e.g., agency and consulting firm reports); these in lacking a conspicuous eye-ring, and having both a sources are relied upon heavily in this chapter. This completely yellow lower mandible and a whitish throat chapter does not address habitat characteristics in that contrasts with a pale olive breast. While these depth, other than for nest sites (refer to A Survey of differences may be subtle, the willow flycatcher also Current Breeding Habitats for additional details).
    [Show full text]
  • Version 2020-04-20 Southwestern Willow Flycatcher
    Version 2020-04-20 Southwestern Willow Flycatcher (Empidonax traillii extrimus) Species status statement Distribution Southwestern willow flycatcher is a distinct subspecies of a wide-ranging species (willow flycatcher), distinguished by its unique call and unique distribution. The southwestern subspecies breeds only along scattered riparian corridors in desert Arizona, New Mexico, and southern California, Nevada, Utah, and Colorado. In Utah its range is now limited to the extreme south, on the Virgin and San Juan Rivers. Southwestern willow flycatcher is thought to winter primarily west of Mexico’s Sierra Occidental. Table 1. Utah counties currently occupied by this species. Abundance and Trends Southwestern willow flycatcher is thought to have undergone large declines, however its restricted range and limited habitat hamper estimates. In 1987, from a minimum 359 known breeding territories, the population was estimated to be between 500 and 1,000 pairs (Unitt 1987). In 1993, the population was estimated to be 230 and 500 pairs (Federal Register 2013), and again in 2007 as 1,299 pairs (Durst et al. 2008). Breeding Bird Surveys in Utah do not distinguish between willow flycatcher subspecies. For the species, Utah BBS data show non-significant -0.46% declines per year throughout the state from 1967-2015 (95% CI: -3.42 to 2.41; Sauer et al. 2017). No population estimate for the southwestern subspecies exists for Utah, though in a 2007 survey, seven southwestern willow flycatcher territories were found in southern Utah, comprising 0.5% of the known flycatcher territories in that year throughout its range (Durst et al. 2008). Currently Southwestern willow flycatcher is: Listed as Endangered by the U.S.
    [Show full text]