English and Scientific
names: |
Fork-tailed Flycatcher (Tyrannus savana) |
Number of individuals: |
1 immature male |
Locality: LOUISIANA: |
Plaquemines |
Specific Locality: |
16096 Hwy. 23 S, Becnel Citrus Farm, Alliance |
Date(s) when observed: |
18 February 2008 |
Time(s) of day when
observed: |
4:40-5:50 PM CST |
Reporting observer and
address: |
Justin Bosler Baton Rouge, LA |
Other observers accompanying reporter who also
identified the bird(s): |
Devin Bosler |
Other observers who independently identified the
bird(s): |
David Muth, Phillip Wallace, Dan Purrington, Curt Sorrells, Dave Patton, Mac Myers, and m. ob. |
Light conditions (position of bird in relation to
shade and to direction and amount of light): |
Good lighting conditions with sun still relatively high in the sky. We positioned ourselves to view the bird with the sun on our backs providing adequate direct light for identification and photos. |
Optical equipment: |
Zeiss Victory FL 8x42 binocular (good condition) and Nikon Fieldscope 60ED w/ 45x optical zoom (fair condition) |
Distance to bird(s): |
~35-40 meters at closest point |
Duration of observation: |
Approximately 1 hour |
Habitat: |
Open residential yard with tall sweet pecans, live oaks, and bald cypresses adjacent to citrus orchard |
Behavior of bird: |
The bird was actively flycatching from medium to high (usually high) perches in bare trees with a group of tyrannids containing 14 Western Kingbirds and 1 Scissor-tailed Flycatcher. Early on, it would perch only for brief periods (5-30 seconds) before venturing out on sometimes prolonged sallies which involved some intense aerial acrobatic moves, a known behavior of FTFL. Its erratic flight while sallying for aerial prey included twisting, spinning, and doubling back on itself to snatch the flies/gnats from mid-air. Using its long rectrices to maneuver, it was able to stop its forward motion and turn on a dime to snag an unsuspecting fly. Towards sunset it stayed on perches longer and sallied less. At 5:50 PM, it went to roost in an orange tree with the kingbirds. |
Description:
|
Thin, attenuated tyrannid with relatively small black bill; complete black cap; white collar clearly separating the light gray mantle from the black cap; very dark brown to blackish flight feathers; long, narrow black forked tail; and entirely white underparts. The outer 3 primaries were not emarginated; therefore, it is an immature (also, clearing ruling out the nominate ssp., since the young of that ssp. would be indistinguishable from adults at this age – nearly 1 year of age). Also lending to this age assignment were the buffy edged upperwing coverts, the shorter length of the tail, and a possible molt limit evident in the secondaries with the inner 3-4 already replaced. The timing of molt is a better match for T. s. monachus. Nominate adults would be fairly worn, as it is the middle of their breeding season, and young of the nominate ssp. would be indistinguishable from the adults by this age, after undergoing their post-juvenal molt during our summer. An apparent white collar, pale gray mantle, and wholly white underparts all match previously described features of the monachus subspecies, and according to Zimmer (1937), these characters are reliable in the field. Additionally, nominate birds tend to show up as overshoots during late spring/summer or as reverse migrants during fall/early winter. I am unaware of any documented savana records in North America between January and March. Due to the date of occurrence, evidence of molt, and overall physical appearance, it is most likely an individual of the Middle American subspecies (monachus), which breeds from s. Mexico to nc. Brazil. This ssp. is regarded as a short distance migrant, usually withdrawing from the northern extent of its breeding range in winter; however, some reverse movements have been solidly documented in Texas (Remsen et al.). |
Voice: |
Unfortunately, no voice was heard. |
Similar species: |
It bears only slight physical resemblance to the scissor-tailed flycatcher due to the long, trailing rectrices. However, it can be easily separated from that species by its thin, attenuated body; black cap; all white underparts, and wholly black rectrices. |
Photographs or tape recordings obtained? |
Digiscoped photos obtained by Justin Bosler, and they are attached. |
Previous experience with this species: |
Observed 5+ individuals of unknown subspecies throughout c. Panama in May 2005. |
Identification aids: |
after observation: Primary literature for dates of occurrence, ageing and separating subspecies. Also, NG Complete Birds of N.A. for other tidbits of info. |
This description is
written from: |
__X___ notes made during the observation (_____notes attached?);_____notes made after the observation (date:_____); __X___memory. |
Are you positive of your identification? If not,
explain: |
Yes, 100% positive. |
Reporter: |
Justin
Bosler
|
Date and time: |
10 March 2008 5:20 PM |