The southwestern willow flycatcher (Empidonax traillii extimus) is a small insect-eating bird that breeds in dense riparian habitats across the southwestern United States. This subspecies of the willow flycatcher has declined precipitously in recent decades and was listed as endangered under the Endangered Species Act in 1995. There are estimated to be only around 1,200 southwestern willow flycatcher territories remaining today. The southwestern willow flycatcher is going extinct primarily due to widespread destruction and modification of its native riparian habitat throughout the Southwest.
What is the southwestern willow flycatcher?
The southwestern willow flycatcher is one of four subspecies of the willow flycatcher native to North America. It is a small, neotropical migrant bird that measures approximately 15 cm long and weighs about 14 grams. The southwestern willow flycatcher can be identified by its olive-gray upperparts, whitish throat, light olive breast, wingbars, eye ring, and tail side patches. Its song is a sneezy “fitz-bew” or “fitz-bree.”
This subspecies breeds in dense riparian habitats near surface water or saturated soil from late May through August across the southwestern United States. Its breeding range includes southern California, southern Nevada, southern Utah, Arizona, New Mexico, western Texas, southwestern Colorado, and extreme northwestern Mexico. The southwestern willow flycatcher winters primarily in the tropical forests of southern Mexico, Central America, and northern South America.
Why is the southwestern willow flycatcher endangered?
The southwestern willow flycatcher was listed as endangered under the Endangered Species Act in 1995. It has declined to endangered status primarily due to widespread loss and degradation of its native riparian breeding habitat across the southwestern U.S. Major factors in the decline of this subspecies include:
Habitat loss and modification
– Damming of rivers and water diversion for agriculture has reduced natural flooding cycles and lowered water tables, causing decline of native riparian vegetation.
– Clearing of riverside habitats and forests for agriculture, urban development, reservoirs, and flood control has removed native habitat.
– Livestock grazing and agriculture near riparian areas has degraded willow and other vegetation.
– Increased fires have reduced riparian habitat.
– Invasion of exotic vegetation, like tamarisk, has altered habitat structure.
Brood parasitism
– Increased brown-headed cowbird populations have led to higher brood parasitism rates, lowering southwestern willow flycatcher productivity.
Small population size
– With under 1,200 territories remaining, the southwestern willow flycatcher has a very small population size that is vulnerable to extinction risks.
Climate change
– Climate change and drought are projected to further degrade riparian habitats in the Southwest.
How many southwestern willow flycatchers are left?
Current population estimates indicate there are approximately 1,200 southwestern willow flycatcher territories remaining. The southwestern willow flycatcher population is distributed across several states, with recent territory estimates as follows:
State | Estimated Territories |
---|---|
California | 174 |
Arizona | 706 |
New Mexico | 120 |
Colorado | 82 |
Utah | 87 |
Nevada | 4 |
Texas | 33 |
Total | 1,206 |
The largest populations remain in Arizona and California. However, even in these states the flycatcher occupies just a fraction of its historical range and breeding territories continue to be lost each year. Without successful conservation efforts, scientists estimate the southwestern willow flycatcher could go extinct within the next few decades.
What is being done to protect the southwestern willow flycatcher?
A variety of conservation and recovery actions are underway to protect the southwestern willow flycatcher and restore its riparian habitat:
Habitat protection and restoration
– Removing invasive plants and sowing native vegetation.
– Restoring natural flooding regimes with managed river flows.
– Fencing off riparian areas from livestock.
– Protecting habitat on public lands.
Captive breeding and releases
– Breeding flycatchers in captivity to supplement wild populations.
– Releasing captive-bred birds into restored habitats.
Cowbird control
– Trapping and relocating brown-headed cowbirds to reduce brood parasitism.
Monitoring and research
– Surveying flycatcher populations each year.
– Banding birds to track movements and survival.
– Researching threats and establishing recovery goals.
Habitat conservation plans
– Developing riparian habitat management plans with states and federal agencies.
Despite these efforts, the long-term survival of the southwestern willow flycatcher remains uncertain due to on-going habitat loss and degradation. Achieving stable or increasing flycatcher populations will require large-scale ecosystem restoration and enhanced legal protections. The possibility oflisting the bird under the California Endangered Species Act, reducing livestock grazing pressures on public lands, preventing development in riparian areas, and mitigating water diversions will likely be necessary.
Conclusion
The southwestern willow flycatcher is going extinct primarily due to the widespread destruction, fragmentation, and alteration of native riparian habitats across the southwestern U.S. Damming of rivers, water diversion for agriculture, urban development, livestock grazing, and the spread of invasive plants have all contributed substantially to the loss and degradation of the dense riparian nesting habitat this species needs to survive. With just 1,200 territories remaining, the southwestern willow flycatcher has declined to dangerously low levels. However, intensive conservation and recovery efforts focused on riparian ecosystem restoration, habitat protection, captive breeding, and cowbird control are underway to try and bring this unique songbird back from the brink of extinction. Protecting the remaining fragile riparian habitats of the Southwest will be key to ensuring the southwestern willow flycatcher, along with many other imperiled animals, gets a second chance to thrive.