56-B-06

Idaho Bird Records Committee Rarities Report Form

Species: Ruby-throated Hummingbird

Date of Observation: 9/17/06

Date Report Prepared: 10/13/06

Locality of Observation: At Three Rivers Ranch, a guest ranch located about nine miles east of Ashton, Fremont County, at the confluence of Warm River and Robinson Creek.

Habitat: Riparian

Conditions: Sunny and warm, sun high at about 10:00AM. Binocs used were Nikon 10 x 42 Premier LX. Distance ranged from a few feet to 20 yards. The bird was around for about 60 minutes and was observed intermittently during that period for a total of about 8-10 minutes. It perched at a feeder several times, foraged at flowers planted near the feeder, and perched in trees nearby. The feathers were fluffed up as if it were cold when I first saw it but later they were held flat.

the same day? Notes prepared the night of the sighting. Additions added at a later date for clarification.

What guide or reference did you consult? Peterson’s Hummingbirds of North America, various photos on web including Satcy Peterson’s photos of Idaho’s first record banded at Mt Home AFB.

Description: Female type hummingbird. Field marks noted in field notes written on 9/17/06:

-Longish bill that curved slightly downward, mostly at the center rather than being evenly curved,

-a pretty white looking throat

-long neck with small head

-gray wash on the underparts

-white upper breast

-a hint of buff on the flank (I think),

-golden green back

-gray auriculars.

-I tried to see if the crown was gray but couldn't see any contrasting color there,

-wing tip was narrow, not wider at the tip

-deeply notched tail when perched

-It pumped it's tail three times when it approached the feeder once but didn't pump constantly and not the exaggerated tail flopping typical of Black-chinned

Small hummingbird, similar to Rufous. Broad-tailed, or Black-chinned. This was the only hummingbird present so size estimate is based on extensive previous experience observing hummingbirds at this location. It did not appear larger than our regular species mentioned above. This bird was slender bodied (even with feathers fluffed) with a long neck and small head. Upperparts bright green with gold highlights, nape and crown concolor with back (I specifically looked at the crown to see if it was gray while it was perched at the feeder). The bill was entirely black, shorter than expected for female Black-chinned but longer than on Anna’s, and was slightly decurved-most of the downward curve was at the center of the bill so it appeared slightly kinked, not evenly decurved. The gray wash on the underparts was not as dark or extensive as Black-chinned in my experience. There was a white band across the upper breast that separated the gray wash on the underparts from the head. Throat was clean white, no stippling noticed but this was not specifically looked for. There was a small area washed with bright buff, not rufous or cinnamon, on the lower flanks. Tail was deeply notched or forked while perched - this trait was seen at close range twice and the notch extended beyond the white spots on the rectrices, which were visible on the folded tail. Central rectrices entirely green. Some rectrices had fairly large white spots but I wasn’t able to determine how many rects had white tips. No rufous was seen in the tail (I looked for Rufous). The tip of the folded wing was seen at close range and was tapered, or narrower at the tip, not getting wider at the tip as in Black-chinned. Tail extended noticeably beyond folded wings when perched. One time when it approached the feeder it pumped its tail three times-three quick flicks of the tail one time rather than pumping during three visits. The tail pumping was shallow and quick, not nearly the exaggerated flopping typical of Black-chinned.

Behavior: It perched at a feeder several times, foraged at flowers planted near the feeder, and perched in trees nearby. The feathers were fluffed up as if it were cold when I first saw it but later they were held flat.

How and when did you positively identify the bird, and what clinched the identification for you? I didn’t have a chance to study the ID until around 10PM on 9/17. At that time I became convinced that it was probably a Ruby-throated. Subsequent study of field guides and online photos/drawings further supported the ID. Personal comments from Stacy Peterson helped eliminate my main concerns about this difficult ID.

Regular species for the location are Rufous, Broad-tailed, and Calliope. Given the time of year either Calypte species, but most likely Anna’s, is possible. The most likely to be confused with Ruby-throat is Black-chinned which is expected, but not terribly common, at this location.

-Rufous is eliminated by the lack of rufous in the tail flanks, or rump/back.

-Broad-tailed has rufous in the tail and a heavily stippled throat.

-Calliope has a much shorter tail and shorter bill and a cinnamon wash on the flanks.

-Both Calypte species are heavy bodied, short-necked and large-headed. Either would have a somewhat shorter bill than this individual as well.

The combination of clean white throat, slender body with long neck and small head, gray wash on underparts and buff restriced to lower flanks put this hummingbird in the genus Archilochus. This is most likely an immature female but immature male may not be able to be eliminated which is not crucial to the identification in this case. Combination of field marks that eliminate Black-chinned are:

-Narrow primaries on folded wing - Black-chinned has very wide primaries that appear to get wider at the tip – immature male shaped similarly to females. This shape is diagnostic within the genus Archilochus.

-Deeply notched tail which is not shown by Black-chinned

-Green back with gold highlights

-crown concolor with nape, not gray as typical for Black-chinned,

-clean white throat – Black-chinned typically shows grayish throat

-shorter, only slightly decurved bill as opposed to longer and evenly and obviously decurved bill of Black-chinned

-Lack of obvious deep tail pumping. In my experience Black-chinned pumps it’s tail much more deeply and slowly. BC also seems to pump its tail constantly making it really stand out in a crowd.

While there is no pattern of occurrence on which to assess timing of this observation there is one other record for RTHU in Idaho. That individual was banded on 9/15 in Mountain Home which helps show that the timing for this sighting is OK. The Mt Home record has not yet been voted on at the time of this report but it is well documented.

I have seen a few RTHUs in NJ and MO but essentially I have no experience with the species. I see hummingbirds five or six days a week during summer at my place of employment where feeders are kept all summer. Most are Calliope with some Broad-taileds during breeding season. In migration Rufous, Calliope and Broad-tailed are common and Black-chinned are uncommon but regular. I see a handful of BCHUs annually here. I also see a number of Black-chinneds at a boat ramp on the South Fork of the Snake River named Byington. The site hosts have feeders and I check them weekly during summer. BCHU is much more common here, usually present when I visit. I have spent a fair amount of time studying these species, especially Black-chinned. I check the wing shape of every Black-chinned female I see. It invariably strikes me as very fat, almost bulbous, at the tip. I used to check tail shape and I’ve never seen a Black-chinned appear close to as forked as this individual. The tail pumping behavior is usually immediately obvious. The long-necked and small-headed overall shape are distinctive and, to my eye, very easy to see.

General experience birding: 13 years

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