Wednesday, April 29, 2015

Sample OBRC Report - Swainson's Hawk

It's that time of year again... Rare birds abound! As always, OBRC reports are best when written quickly. We had a distant Swainson's Hawk at Beamer CA  back on April 25th, and I wanted to get my thoughts down on paper ASAP. It was submitted within 24 hours! There may be spelling mistakes and other errors, but the general picture is complete. I also submitted two copies of recent weather stations (Burlington and Hamilton) as well as my ebird checklist:

http://ebird.org/ebird/view/checklist?subID=S23057566


Send them to obrc@ofo.ca !!!! Here is my sample.. These things get longer when photos are not involved... Would you accept it!?

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OBRC Report – Swainson’s Hawk

1 – age unknown, morph unknown

Beamer Conservation Area, Grimsby

April 25th, Just before 4pm (I think, didn’t check the time right away)

Optics: Vortex Razor 20-60x Spotting Scope, Vortex Razor 8x42 binoculars

Circumstances: 

Heavy flight of BWHA on blue skies. One group over 125 in the morning, 800+ in two hours between 12-2pm. I was with my family and not watching as steadily as I may have in the past (went for a long walk etc). Beautiful day! Winds NE or E, with Lake Ontario influencing the direction and intensity. See screen captures of local weather stations. 100% blue sky overhead, but thick wispy cloud building to the south.

Among the flight, three hawks appeared to the south and crossed over the “plain” – the area south of the hawk tower but north of Ridge Rd. They were high, but not terribly. The combination of height, blue sky, and direction (looking south) meant that viewing conditions were less than ideal, showing very little in the way of colour, but excellent for viewing shape/structure. These birds were a part of the general flight line at the time, with groups passing closer overhead or further south leading up to the observation. With the east winds, birds were moving through quickly, and not forming large kettles or circling for very long before continuing on their way (long strings of birds between short periods of kettling). I wasn’t entirely sure if these three birds were part of a larger group or not (as I was focusing my attention on them, and not what was around them. They were pushing through west – two were clearly Broad-winged Hawks (shorter wings, smaller size, standard for the day) whereas the third bird was considerably larger. All three were clearly buteos, but the third (noted) bird was long winged and light looking. They stopped to kettle for maybe 60 seconds, changing shape and showing full spread, and then glided west and out of view. All visible features (even in the poor lighting and height/distance) indicated the bird was a Swainson’s Hawk (as detailed below).

Description:

- Long-winged Buteo

- Long tail

- Light flapping & smooth (not unlike a BWHA, given the structural differences)

- Looked small when viewed alone

- Considerably larger than BWHA when grouped together (much longer wings, tail)

- Initial impressions from other observers on the tower flopped between BWHA and RTHA due to these factors

- Showed obvious dihedral when soaring

- Even when soaring, wings were long and thin

- Even when soaring (throughout obs) wings looked more “pointed” than other buteo. I couldn’t count them, but I would say this is a factor of the 4-pointed hand of SWHA vs. 5 point of RTHA & RLHA

- Appeared dark to darkish overall with no field marks noted on the plumage



Similar Species:

Northern Harrier – bird was clearly a buteo with different wings and a shorter/broader tail. Much too large.

Red-shouldered Hawk – no crescents, wings too long, flaps not choppy like RSHA. Too large vs. BWHA.

Broad-winged Hawk – direct comparison provided size/shape elimination

Red-tailed Hawk – bird was much lighter/slimmer looking than the heavy impression of RTHA. Wings much too long and thin (lacking the RTHA bulge), dramatic difference in shape when circling/kettling with the BHWA’s than a RTHA. More pointed impression of the wings does not fit the broad “hand” of RTHA. Dihedral when soaring is unlike RTHA. I am well aware of the pitfalls of juv RTHA’s with their longer flight feathers and lankier appearance than adults. We saw several RTHA this day alone. Something I’m not really aware of, but the BHWA like flapping and keeping pace with BWHA when on a hard glide is not something one would expect a RTHA to do.

Rough-legged Hawk – Bird gave too much of a BWHA like impression compared to the wide/long features of RLHA. More pointed wingtips when kettling vs. the broad hand of RLHA. Had more dihedral than expected for RLHA. When flapping, did not strike me as a RLHA-type flap… Keeping pace with BW’s (as noted under RTHA) may be at odds with RLHA, but I lack experience judging that (they seem to do their own thing, rather than directly join in the strings/kettles). I also believe the bird was close enough that I would have been able to see some of the bold RLHA markings in the scope (any morph).



Experience with species:

I have seen two Swainson’s Hawks (in migration) previously in Ontario and maybe 100 in Manitoba and Saskatchewan during the breeding season.

As for hawkwatching in Ontario, I have been visiting Beamer since the mid-late 1990’s and began my serious interest in birding there. I have likely spent a few hundred days hawkwatching both for fun, and at work, throughout Ontario from Rainy River, Lake Superior, Georgian Bay, Lakes Huron, Erie and Ontairo and Netitishi Point on James By (spring and fall for many of these) – seeing untold numbers of our local species – as well as experience elsewhere in the USA (Florida, Cape May, Hawk Mountain etc). I would say I have more experience watching migrating hawks than any other family of birds.


Comments:

I did not see the bird well enough to know this, but I suspect it was a juvenile – which may have been the reason that I couldn’t see any real “field marks” on the plumage, even when viewed in the scope – leading to an overall “dark-ish” impression, as even intermediate birds are pretty dull underneath compared to the light undersides we normally see on RTHA, juv RSHA, BWHA etc. I do not think it was a true “dark morph” though. But that’s a guess!

I’m also well aware that this is a bit of a “challenging” sighting, relying on “hawkwatching” techniques of GISS and behaviour than visual field marks, but I have enough experience in using them to call the bird to species.

Matt Mills also independently saw the bird ahead of me, and went running down the road to try and get a better look due to the notable structural differences noted here – which helps to show that it was clearly something we are not used to seeing at Beamer or in Ontario. I didn't connect with him until the following day though!


Brandon Holden
contact info yada yada yada...


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Get out there and find those good birds! I keep posting my rarity-weather predictions on twitter! Check it out! 


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