| Willow flycatcher | |
|---|---|
 | |
| E. t. extimus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Tyrannidae |
| Genus: | Empidonax |
| Species: | E. traillii |
| Binomial name | |
| Empidonax traillii (Audubon, 1828) | |
 | |
| Approximate distribution map Breeding Migration Non-breeding | |
The willow flycatcher (Empidonax traillii) is a small insect-eating, neotropical migrant bird of the tyrant flycatcher family native to North America.
There are four subspecies recognized, all of which breed in North America (including three subspecies that breed in California). [2] At one time, this bird and the alder flycatcher (Empidonax alnorum) were considered to be a single species, Traill's flycatcher. Their song is the only reliable method to tell them apart in the field. [3] [4] The binomial commemorates the Scottish zoologist Thomas Stewart Traill.
The subspecies are best distinguished from each other by their songs. In addition, the four subspecies have significant genetic differences based on mitochondrial DNA analysis. [2] Their winter ranges have been elucidated using mitochondrial DNA genetic studies of 172 birds sampled in winter combined with plumage coloration and morphological differences.
The four subspecies of the willow flycatcher are:
The little willow flycatcher (E.t. brewsteri) is the Pacific Slope subspecies of the willow flycatcher. Described by Oberholser in 1918, it breeds in California from Tulare County north along the western side of the Sierra Nevada, and in Oregon and Washington west of the Cascade range.
The Great Basin/Northern Rockies subspecies of the willow flycatcher (E. t. adastus) breeds in California east of the Sierra/Cascade axis, from the Oregon border into Modoc County and possibly into northern Inyo County. Populations at high elevation just east of the Sierra Nevada crest but south of Modoc County are assumed to be E. t. brewsteri. There has been very little study of E. t. adastus in California. It was described by Oberholser in 1932.
The southwestern willow flycatcher (E. t. extimus) is a federally endangered subspecies found in Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah. It was listed in 1995, when it was known to breed at only about 75 sites in riparian areas throughout the American southwest. The breeding population was estimated at between 300 and 500 pairs. Breeding occurs from near sea level on the Santa Margarita River to 800 m (2,640 ft) at the South Fork Kern River and 910 m (3,000 ft) at upper San Luis Rey River in California and to over 2,600 m (8,530 ft) in Arizona, southwestern Colorado, and north-central New Mexico. This subspecies was described by A.R. Phillips in 1948.
The largest remaining population in California is on the South Fork Kern River, Kern County. In southern California, this subspecies breeds on the San Luis Rey River, at Camp Pendleton, the Santa Margarita River and Pilgrim, De Luz, French, and Las Flores creeks; as well as on the Santa Ynez River. In 1996, breeding was confirmed along the Arizona side of the lower Colorado River at Lake Mead Delta and at Topock Marsh. Examination of museum specimens of 578 migrating and wintering E. t. extimus indicate that Guatemala to Costa Rica constitutes the main winter range.
This species is experiencing population declines throughout the Southwest due to habitat loss/alteration and invasive grass species. One of these is saltcedar ( Tamarix ramosissima), found throughout the Southwest, where it has replaced essential vegetation by outcompeting native species in riparian areas where the southwestern willow flycatcher is found. [5] In two sites, one in Arizona and the other in New Mexico, native trees were able to replace patches of saltcedar and populations of willow flycatchers increased. In these sites 90% of the willow flycatcher's nests were found in native vegetation, only 10% were in mixed vegetation (native species and saltcedar) and few were in areas dominated by saltcedar. [6] However, because willow flycatchers can and do breed in some locations within saltcedar habitat, it occasionally serves as vital habitat in the recovery of this species. [7]
The San Pedro River Preserve was purchased by the Nature Conservancy to preserve habitat for this subspecies. NatureServe considers the subspecies Imperiled. [8] North American beavers (Castor canadensis) are thought to play a critical role in widening riparian width, openings in dense vegetation, and retention of surface water through the willow flycatcher breeding season.
The eastern nominate subspecies of the willow flycatcher (E. t. traillii) was described by Audubon in 1828. It breeds from the eastern coast of the United States to the western Rocky Mountains.
Adults have brown-olive upperparts, darker on the wings and tail, with whitish underparts; they have an indistinct white eye ring, white wing bars and a small bill. The breast is washed with olive-gray. The upper part of the bill is gray; the lower part is orangish.
| Standard Measurements [9] [10] | |
|---|---|
| length | 130–150 mm (5.2–6 in) |
| weight | 13.5 g (0.48 oz) |
| wingspan | 220 mm (8.5 in) |
| wing | 68.7–75.6 mm (2.70–2.98 in) |
| tail | 54–64.5 mm (2.13–2.54 in) |
| culmen | 10.5–12.3 mm (0.41–0.48 in) |
| tarsus | 15.5–18.0 mm (0.61–0.71 in) |
Their breeding habitat is deciduous thickets, especially willows and often near water, across the United States and southern Canada. They make a cup nest in a vertical fork in a shrub or tree.
These neotropical birds migrate to Mexico and Central America, and in small numbers as far south as Ecuador in South America, often selecting winter habitat near water. Willow flycatchers travel approximately 1,500–8,000 km (930–4,970 mi) each way between wintering and breeding areas. [11]
This bird's song is a sneezed fitz-bew. The call is a dry whit.
Willow flycatchers are generalist insectivores, and the insects which comprise their diet vary substantially across different habitats. [12] For example, flies of the order Diptera made up the majority of adult willow flycatcher diets in Ontario, Canada, [13] but only composed 10.6% of the diet of California flycatchers, who instead favor Lepidopterans, mayflies, and snakeflies. [14] They are "sit-and-wait" predators, remaining on a perch near the top of a shrub and flying out to catch insects on the wing, but are also reported to glean insects off of leaves and stems. [15]
The alder flycatcher is a small insect-eating bird of the tyrant flycatcher family. The genus name Empidonax is from Ancient Greek empis, "gnat", and anax, "master". The specific alnorum is Latin and means "of the alders".
The Virgin River is a tributary of the Colorado River in the U.S. states of Utah, Nevada, and Arizona. The river is about 162 miles (261 km) long. It was designated Utah's first wild and scenic river in 2009, during the centennial celebration of Zion National Park.
The ecology of the Sierra Nevada, located in the U.S. states of California and Nevada, is diverse and complex. The combination of climate, topography, moisture, and soils influences the distribution of ecological communities across an elevation gradient from 500 to 14,500 feet. Biotic zones range from scrub and chaparral communities at lower elevations, to subalpine forests and alpine meadows at the higher elevations. Particular ecoregions that follow elevation contours are often described as a series of belts that follow the length of the Sierra Nevada. There are many hiking trails, paved and unpaved roads, and vast public lands in the Sierra Nevada for exploring the many different biomes and ecosystems.
The San Pedro River Preserve is a Nature Conservancy preserve in Dudleyville, Arizona.
The slate-colored fox sparrow group comprises the Rocky Mountain taxa in the genus Passerella. It is currently classified as a "subspecies group" within the fox sparrows pending a more-thorough genetic assay of all forms.
Hammond's flycatcher is a flycatcher in the family Tyrannidae. This small insectivorous bird inhabits the coniferous and mixed forests of western North America. The name of this bird commemorates William Alexander Hammond who was the surgeon general of the US Army. Hammond collected bird specimens for Spencer Fullerton Baird.
The American gray flycatcher, American grey flycatcher, or just gray flycatcher as it is known in North America, is a small, insectivorous passerine in the tyrant flycatcher family. It is common in the arid regions of western North America, especially the Great Basin. From sagebrush steppes to pinyon-juniper woodlands and ponderosa pine forests, this flycatcher forages for insects from shrubs or low tree branches.
Skinner Reservoir, also known as Lake Skinner, is a reservoir in western Riverside County, California, located at the foot of Bachelor Mountain in the Auld Valley, approximately 10 miles (16 km) northeast of Temecula. It was created in 1973 by the construction of the Skinner Clearwell Dam on Tucalota Creek, and currently has a capacity of 44,200 acre-feet (54,500,000 m3). Located north of Rancho California Road near the Temecula Valley Wine Country, The address of the reservoir is: 37701 Warren Road, Temecula, CA 92592.
The San Pedro River is a northward-flowing stream originating about 10 miles (16 km) south of the international border south of Sierra Vista, Arizona, in Cananea Municipality, Sonora, Mexico. The river starts at the confluence of other streams just east of Sauceda, Cananea. Within Arizona, the river flows 140 miles (230 km) north through Cochise County, Pima County, Graham County, and Pinal County to its confluence with the Gila River, at Winkelman, Arizona. It is the last major, undammed desert river in the American Southwest, and it is of major ecological importance as it hosts two-thirds of the avian diversity in the United States, including 100 species of breeding birds and almost 300 species of migrating birds.
Tamarix ramosissima, commonly known as saltcedarsalt cedar, or tamarisk, is a deciduous arching shrub with reddish stems, feathery, pale green foliage, and characteristic small pink flowers.
Diorhabda carinulata is a species of leaf beetle known as the northern tamarisk beetle, which feeds on tamarisk trees from southern Russia and Iran to Mongolia and western China. This beetle is used in North America as a biological pest control agent against saltcedar or tamarisk, an invasive species in arid and semiarid ecosystems.
Diorhabda elongata is a species of leaf beetle known as the Mediterranean tamarisk beetle (MTB) which feeds on tamarisk trees from Portugal and Algeria east to southern Russia. The MTB is used in North America as a biological pest control agent against saltcedar or tamarisk, an invasive species in arid and semi-arid ecosystems.
Diorhabda carinata is a species of leaf beetle known as the larger tamarisk beetle which feeds on tamarisk trees from Ukraine, eastern Turkey and Syria east to northwest China, Kyrgyzstan and Pakistan, extending as far south as southern Iran. It is used in North America as a biological pest control agent against saltcedar or tamarisk, an invasive species in arid and semi-arid ecosystems.
Diorhabda sublineata is a leaf beetle known as the subtropical tamarisk beetle (STB). The species was first described by Hippolyte Lucas in 1849. It feeds on tamarisk trees from Portugal, Spain and France to Morocco, Senegal, Algeria, Tunisia, Egypt, Yemen, and Iraq. It is used in North America as a biological pest control agent against saltcedar or tamarisk, an invasive species in arid and semi-arid ecosystems.
The Imperial National Wildlife Refuge protects wildlife habitat along 30 miles (50 km) of the lower Colorado River in Arizona and California, including the last un-channeled section before the river enters Mexico. The Imperial Refuge Wilderness, a federally designated, 15,056-acre (60.93 km2), wilderness area is protected within the refuge. It also surrounds the Picacho State Recreation Area. This section of the Colorado River is popular for boating, hiking, fishing, camping, exploring old mining camps and wildlife watching.
The Bill Williams River National Wildlife Refuge protects the lower course of the Bill Williams River, to its mouth at Lake Havasu reservoir, in western Arizona. It is located within eastern La Paz and Mohave Counties, in the Lower Colorado River Valley region.
Canebrake Ecological Reserve is a 6,700-acre (27 km2) nature reserve in the South Fork Valley of Kern County, 20 miles (32 km) east of Lake Isabella, California. It is located in the Southern Sierra Nevada region.
The Audubon Kern River Preserve is a riparian nature reserve owned by the National Audubon Society in the US state of California, near Weldon in Kern County.
The Arizona Mountains forests are a temperate coniferous forests ecoregion of the southwest United States with a rich variety of woodland habitats and wildlife.
The western flycatcher is a small insectivorous bird in the family Tyrannidae. It is native to western North America, where it breeds in the Rocky Mountains and Pacific Coast forests and mountain ranges from California to Alaska and south to central Mexico; northern populations migrate south to Mexico for the winter.
