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Yellow-bellied Flycatcher

(Empidonax flaviventris)
Indianapolis, Fall 2011

General Information

The approximately 425 species of New World Tyrant Flycatchers make up the largest family of birds found worldwide. Of these, 36 species breed in the US and Canada. Eleven of these are in the Genus Empidonax, the “Empids” a term meaning "King of the gnats," Of these 11 species, 5 regularly occur in eastern North America, including the Acadian, Least, Willow and Alder Flycatchers.

During the breeding season, the "Empids" are relatively easy to identify by song and breeding habitat, but during migration, flycatchers in this group are particularly difficult and perhaps impossible to safely identify unless in the hand, and even then they can be a challenge. The song of each species is distinctive, however, so identifications can be made with vocal individuals. The song of the Yellow-bellied Flycatcher is “chi-lek,” with the first note at a lower pitch than the second.

Most flycatchers feed by "sallying," where they sit on a perch, fly out to catch an insect, and then return to the same or another perch close by.

The Yellow-bellied Flycatcher (Spanish name: Mosquero de vientre amarillois) is less commonly seen than the other Empids and in the spring, is the last Empidonax to migrate north in eastern North America.

This particular individual is a juvenile that was migrating with a small flock that stopped over in September at the Fort Benjamin Harrison State Park in NE Indianapolis. This individual was captured, banded and released unharmed to continue its journey to central and South America, where they spend their winters in semi-open habitats of Central America, including coffee plantations. Shade-grown coffee plantations have higher densities than sun-grown coffee plantations.

 

The flycatchers in this group are small and drab, with two pale wing bars and a light eye-ring. The individual shown here is an immature bird that does show some of the yellowish under parts and throat that separate the Yellow-bellied from the other fly catchers in this group that occur in eastern North America.

Yellow-bellied Flycatcher
Figure 1 – Immature Young Yellow-bellied Flycatcher

 

Yellow-bellied Flycatcher
Figure 2 – Wing of Immature Yellow-bellied Flycatcher

 

The two pale wing bars are readily seen in this photo. Young birds have a yellowish wash, but adult birds show white in the wing bars. Also note the yellowish leading edges of the secondary and tertial feathers. These will also turn white when the flight feathers are replaced next summer.

The shape of the lower mandible is useful to separate the various species of flycatchers in this group. The Yellow-bellied has a relatively broad, short lower mandible. The dark region near the tip of the mandible indicates that the bill has not yet completely developed. Also note the rictal bristles around the mouth. These are specially modified sensory feathers characteristic of aerial insect-eating birds.

Yellow-bellied Flycatcher
Figure 3 – Immature Yellow-bellied Flycatcher

 

Yellow-bellied Flycatcher
Figure 4 – Immature Yellow-bellied Flycatcher

 

This photo shows the white eye ring that is characteristic of this group of flycatchers. The rectal bristles around the mouth can also be seen here. These birds eat mostly beetles, bees, ants, wasps, tent caterpillars, moths, leaf rollers, flies, and spiders. Mountain ash berries and possibly other plant materials round out the diet.

The yellow on the throat is visible in this photo. The yellow throat is an important clue to separate this species from the other eastern Empids, all of which have white throats.

Yellow-bellied Flycatcher
Figure 5 – Immature Yellow-bellied Flycatcher

 

Yellow-bellied Flycatcher
gure 6 – Fall Yellow-bellied Flycatcher

 

The yellow wash on the feathers on the underside of this bird are seen here.

This photo shows a clear dark fault bar. Fault bars develop when the growth of feathers is affected by some disruptive physiological or environmental factor that slows the growth over a short period of time, such as the loss of a parent, or an extended weather phenomenon that prevents feeding of the young by the parents.

Dark regions develop during periods of slower growth, while faster growth results in lighter regions. When all feathers grow in at the same time, the dark bars will be lined up across the feathers as seen here. This occurs when the bird is growing in its first set of flight feathers, but can also occur if an adult bird loses all of its tail feathers and then replaces them all at the same time.

Yellow-bellied Flycatcher
gure 7 – Fall Yellow-bellied Flycatcher tail feathers

 

Breeding Biology

Flycatchers in the Empidonax group are fussy about the habitat that they breed in. The Yellow-bellied Flycatcher prefers Spruce-Fir forests and bogs from the northern edge of the US north into Canada. A cup nest consisting of rootlets, weed stems, moss and grass built by the female is placed on or near the ground on a mossy hummock or among tree roots of a fallen tree. It is usually sunk into and hidden by moss. From 3 to 5 slightly glossy white eggs with speckles and blotches of brown, pink, buff cinnamon or purple are incubated by the female for about 15 days to hatch. The young are tended by both parents until they fledge nest in 13 days.

Banding Recoveries

The records at the Bird Banding Laboratory show that from 1960 to 2011, 39,396 Yellow-bellied Flycatchers were banded and released. Of these, 6 have been encountered at locations away from the area where they were banded (foreign recaptures).

If you should recover a banded bird, please report the band number to the Bird Banding Lab by calling 1-800-327-BAND or online at the web site of the Bird Banding Lab. Your report will add valuable information to what is known about this species, and you will receive an attractive certificate confirming details of your report.

Conservation

According to the USDA Forest Service Conservation Assessment for this species, trend data generated by breeding bird surveys conducted since 1966 for the North American meta-population of the yellow-bellied flycatcher has exhibited a positive trend in rate of increase in detections: +2.63 for the period 1966-1999 and +3.20 for the period 1980-1999. More populations have been on the increase than populations on the decrease throughout the breeding range. In Pennsylvania, Gross (1999) reported that the species successfully fledges young in sites where it is observed breeding and suggested that as additional potential nesting sites are explored the possibility exists that more nesting birds will be found.

Habitat loss on the breeding grounds seems to be the primary cause of population declines in some regions.

Further Reading

Baicich, P. J. and C. J. O. Harrison. 1997. A Guide to the Nests, Eggs, and Nestlings of North American Birds. 2nd Ed. Academic Press, Boston. 347 Pp.

David S. deCalesta, D. S., 2000. Conservation Assessment for Yellow-bellied Flycatcher (Empidonax flaviventris). USDA Forest Service, Eastern Region. Milwaukee, WI. 11Pp.

Gill, F. B., 2007. Ornithology, 3rd Edition. W. H. Freeman and Company. 758 Pp.

Gross, D. A. 1992. Yellow-bellied flycatcher. Pages 198-199 in Brauning, D. W. (ed.). Atlas of breeding birds in Pennsylvania. University of Pittsburgh Press. Pittsburgh.

Peterson, R. T. 2009. Peterson Field Guide to Birds of North America. 1st Edition. Houghton Mifflin Co., Boston. 527 Pp.

Pyle, P. 1997. Identification Guide to North American Birds. Part I. Slate Creek Press, Bolinas, CA. 731 Pp.

Terres, J. K. 1995. The National Audubon Society Encyclopedia of North American Birds. Wings Books, NY. 1,109 Pp.

Yellow-bellied Flycatcher. 2009. Thayer Birding Software LLC. V5.0.2

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