Friday, October 16, 2009

Lucky Peak Songbird Migration Totals

On Thursday, October 15 we netted for songbirds for the last time in 2009 and then took the nets down. Probably due mostly to the weather, our last two days had rather lackluster totals (we captured only 21 birds each day) that were dominated by Dark-eyed Juncos. BUT, we did catch several of the fattest juncos of the season, including a male that weighed 23.1 grams (any junco weighing in @ 20g or more is definitely carrying a lot of migratory fuel but 23.1 is really fat!).
Late season 2009 songbird crew, from left: Heidi, Jay, Caroline (sweet hat!),
, and Stephanie

(we also had help from Jack & Rob earlier in the season and Gary, Erin, Micah, Randy, Dave, & Carol throughout)

In all, we captured 5,748 birds of 61 species in 2009; this marks the 5th highest season total and capture rate (5,748 birds in 4,364 mist net hours = 1.317 birds per mist net hour) in the 13 seasons so far. Thus, 2009 was a little above average ... which is still really good, especially in comparison with most other banding stations I know of that have significantly lower capture rates.

The top ten:
  1. Dark-eyed Junco 799 (includes a single-day record 170 juncos on 10-10)
  2. Western Tanager 697 (new season record)
  3. Ruby-crowned Kinglet 638 (lowest season-total to date)
  4. White-crowned Sparrow 495
  5. Dusky Flycatcher 322
  6. Spotted Towhee 285 (2nd highest season total)
  7. MacGillivray's Warbler 283
  8. Yellow-rumped Warbler 226
  9. Nashville Warbler 195
  10. Yellow Warbler 192
We captured 3 new species in the songbird nets this year, including an American Kestrel on Aug 21 (a common migrant at the site that had never been caught in the songbird nets) as well as the much more rare Hermit Warbler on Aug 6 and an Indigo Bunting on Sept 12 (see prior blog posts for pics of these two). Other unusual species captured in 2009 included a Green-tailed Towhee on July 29, a Gray Flycatcher on Aug 2, a Yellow-breasted Chat on Aug 20, an American Redstart on Aug 27, a Rose-breasted Grosbeak on Sept 9, a Least Flycatcher on Sept 15, a White-breasted Nuthatch on Sept 26, and a Varied Thrush on Sept 29.

We set or tied season records for a number of species in 2009, including Western Tanager (n=697), Cassin's Vireo (131), Lazuli Bunting (91), Swainson's Thrush (45 - 19 better than the previous high of 26!!), 'Western' Flycatcher (22 - a tie with 2006), Black-chinned Hummingbird (16), Song Sparrow (9), and Savannah Sparrow (4). Also, though we hardly captured any compared to the # that was around, we had an amazing late fall for American Robins - hundreds were around the site for a couple weeks straight and the hawkwatchers estimated over 2,250 robins flying past on one day!

Notably absent again was Northern Pygmy-owl which we had captured at least one per season for the first 11 years and then none in 2008 or 2009 after a record season in 2007 (???). Also, though I don't see any reason for concern for most of the species that we catch (based on the raw numbers anyway; still awaiting a more rigorous analysis of population trends) and most species numbers are either stable (with some cyclic and/or inter-annual variation) or increasing, my concern for the status of Golden-crowned Kinglets continues to grow.

A trio of very cute Golden-crowned Kinglets captured together in fall 2006 - photo by Caroline Poli

Though we detected this species by their high-pitched call notes most days in September and October, we captured/banded only 11 in 2009 and this is the lowest season total yet. It could be that shifts in their feeding (i.e., maybe concentrating their feeding in the Douglas-fir trees even more than usual) could be driving this pattern but we captured at least 60 individuals from 1997-2001 and numbers have generally been much lower since (see the below Excel graph to get a sense of the trend in annual captures for GC Kinglets):

In contrast, the following Excel graph shows the annual capture rate for all songbirds combined during the same period:
As you can see, the combined total for the songbird community as a whole paints a positive picture - stable if not slightly increasing. Thus, why the apparent decrease in Golden-crowned Kinglets?? Something to look into ....

I'll post again with the final raptors #s and/or if something unusual shows up.




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Val Lee said...

Great work Jay and staff. It is a steep trek to travel up and witness your faithful work of diligence and endurance; nevertheless, sooooo worth the drive. How thrilling to be an observer of those magnificent ave mechanisms of God’s creation!

Val Lee (I write and submit photos for Lee's Birdwatching Adventures Plus "Through the Looking Glass of Val Lee")

Bob and Robin said...

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Mission: to contribute to the conservation of western migratory landbirds through cooperative research and public education