Wondering about Waxwings

[David Suddjian]

Hi CoBirders,

The Bohemian Waxwing is having a major eruption now in the Denver Metro area and elsewhere along the Front Range.  eBird shows BOWA has periodic irruptions of varying degrees here (but not always at the same season); most seasons they are missing or rare. Looking at eBird data for the Front Range counties, the last eruption year with a comparable winter frequency of occurrence to right now was in 2008. There have been some lesser Bohemian appearances in the intervening years, but often not peaking in early January.

Since BOWA is numerous, I wondered how the Cedar Waxwing was doing compared to "normal", as there seem to be lots of reports of them, too. I looked at eBird for the Denver Metro area and the Front Range counties from Larimer to El Paso. You can view parameters for five-year periods for a single species. Shown here are graphs for Frequency (left) and for Abundance (right) for Cedar Waxwing in 2019 to 2023. (The line for 2023 is only a few weeks long, so the rest of the year just looks flat-lined on the charts.) 

(left hand graph) Cedar is far more frequently detected now than in the prior four Januaries, and looking back at still earlier years I see no other peaks as high as now for frequency of occurrence in winter, a time when the species is usually not particularly frequent (note the breeding season is the usual peak for CEDW frequency). 

(right hand) Cedar is more abundant than the other recent Januarys, and the numbers now are at a peak comparable to the highest peaks in the other years. Interestingly, the peak numbers in other years are spread from fall to early spring. 

David Suddjian

Ken Caryl Valley

Littleton, CO

[Megan Miller]

I'd be curious to compare it to their northern ranges as well. Are they equally abundant in their traditional winter ranges?

Are they are moving south because they have exhausted northern food sources? 

or because food sources are so abundant it enabled a population boom this year causing birds to be pushed out of their traditional ranges (much like the Snowy Owls?).

I feel like the finch research network has answered that question but I haven't read their winter finch forecast since November and I don't remember what they said. 

Some notes on aging Bohemian Waxwings! 

A Second Year Bird (SY) is a bird that hatched last summer and had its first "birthday" on Jan 1, 2023. 

It's designated as an SY bird ( or FCF if you're adopting the new WRP system)

Most waxwings without waxy tips are considered younger birds BUT some HY/SY birds can have up to 8 waxy tips so proceed with caution. 

Pyle also mentions the white tips on the primaries as an additional indication of age.

Adult birds have a full "Nike swoop" checkmark on the primaries and SY birds only have a small white rectangle that doesn't swoop.

An Adult Bird- notice how the white edge on each primary wraps around to form a swooping shape.

Hatch year bird- the white edging is restricted to just the side of the feather and doesn't wrap around the tip.

Here is a link to a photo of a group of Hatch Year birds on the ground and an adult bird on the left flying in. 

notice how the bird flying not only has the Nike Swoop but also six secondaries worth of waxy tips. 

Going through photos folks have taken this year I'm not seeing a lot of After Hatch Year/ adult birds. Mostly younger HY birds. 

Maybe this supports a population boom where many younger birds are being pushed southward? 

Happy birding!

Megan M 

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[David Suddjian]

I erred in stating the right hand graph was of Abundance, but actually it is the Average Count. "Average Count" givse the average number of waxwings using only checklists on which the waxwing was reported for the calculation. The slide is corrected below.

On Wed, Jan 18, 2023 at 10:29 AM David Suddjian <dsud...@gmail.com> wrote: