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Tuesday, May 2, 2017

Massive migration in..LA county!

Should I've just stayed home instead of tramping East..

e: 4/27/17 10:16 am
From: Kimball Garrett <kgarrett...> [LACoBirds] <LACoBirds-noreply...>
Subject: [LACoBirds] Massive migration at windy Hansen Dam

I spent about 45 minutes (0720-0805) at Hansen Dam this morning (27 April), observing mainly from the upper portions of the ball field area, just south of the dirt parking lot east of the restroom/office building off Foothill Blvd. The migration of passerines, etc., was phenomenal, exceeding anything I can recall seeing on the deserts or the Gulf Coast (though I admit I've never hit the really big fallouts in those areas). Mark Scheel was leaving as I arrived, and he had been seeing a similar spectacle. Clearly these big visible movements are related somehow to the strong and persistent N winds in the area the past few days, including overnight and (10-15 mph) while I was there this morning. I'm not sure how the geography of this site funnels birds the way it does, but I suspect these birds were blown farther south than they "wanted" to be and were reorienting by skirting the south flank of the Verdugos and continuing WNW to NW right over the Hansen Dam Basin. Tellingly, I saw essentially no migrants while driving along Foothill Blvd. from Tujunga to Hansen Dam (nor, later, while driving down the Glendale Fwy. to work), so the passage seemed to be along a fairly well-defined path.

Western Tanagers (125), Lazuli Buntings (40), Black-headed Grosbeaks (25), Western Kingbirds (20) and Ash-throated Flycatchers (45, including 6 perched together at one point) were the most conspicuous migrants, but there were >>100 warblers, 10+ Warbling Vireos, 8+ Bullock's Orioles, etc. Absent, on the other hand, were Empidonax flycatchers and Catharus thrushes. The warblers were very frustrating - though many would land high in the picnic area pines and other trees, they were pretty much invisible there because of the winds. Nevertheless, at least 7 species were moving through, including 4+ Hermits. On top of this, there were dozens to hundreds more passerines moving in the distance or high in the air.

Other migrants included two Phainopeplas, an Acorn Woodpecker (moving on the same WNW path), 60+ Vaux's Swifts, and five Purple Martins (4 males and a female moving WNW over the lake). A fairly late American Pipit was also flying over.

The eBird checklist is here:

If the winds continue through the night tonight, it might be worth checking this area Friday morning. In the absence of winds, migration here has been considerably more mundane.


Kimball L. Garrett
Ornithology Collections Manager
Natural History Museum of Los Angeles County
900 Exposition Blvd.
Los Angeles, CA 90007 USA
(213) 763-3368

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