[CT Birds] Weekend Forecast -- windy, with high chance of rare birds!

Tina and Peter Green petermgreen at hotmail.com
Sat Oct 15 16:04:02 EDT 2011

This may be of interest to CT birders posted by Marshall Iliff on Massbird.
Tina Green

 Several conditions are aligning this weekend to make for what may potentially be a great weekend for birding and could very well bring an additional slug of top-level rarities.

Rare bird prognostications are an imperfect science, for sure, and certainly I won't be totally surprised to be completely wrong. But for those who like a challenge, are interested in the science of birds and weather and the not-so-random appearances of "vagrants", this would be a good weekend to get out afield.

Here are a few things to think about:

1) This fall has already had a large number of rarities turning up. I assume this is due to the same dip in the jet stream that has brought us such cool, moist weather all summer and fall, yet with consistent southerlies. Consider the birds recently: Lark Bunting; Smith's longpsur in ME; multiple Ash-throated Flycatchers (Plum Island and Winthrop); Townsend's Warblers in NJ and MD; Black-throated Gray Warbler in NJ; Green Violetear and Bell's Vireo in Maryland, etc.

2) The long, trailing offshore system a couple weeks ago produced one of the more impressive fallouts of southern passerines along the coast from Boston to central Maine. (My impression is that birders did not cover places like Cape Ann well enough; Cape Ann may have been superb on Sunday and Monday 2-3 Oct, but the best coverage there was 5-6 days later). Impressively, many of the birds (Hooded Warblers, White-eyed Vireos, Summer Tanager, cuckoos etc.) have persisted through this week and some are setting very late records (e.g., the multiple recent Yellow-throated Vireos). Since some of these birds may still be around in coastal thickets, it is yet another reason to get out and look.

3) Most importantly, this weekend's weather could very well bring some new rarities. We are now in the middle of two very wet cold fronts moving up from the south (as did the system 2 weeks ago that brought these southern landbirds). This wet weather is scheduled to clear tonight and behind it a third low pressure system will bring strong westerly winds. This system has been tracking across southern Canada and the Great Lakes and will have pretty long wind fields that have good potential to displace birds--in other words, this could be a good weekend for vagrants. Over the weekend wind is forecast (at e.g., Gloucester) to be 15-20 mph or higher from the WSW or SW. 

This system does not have the "ideal" conditions to displace southwestern birds to New England. This type of system--best known for Cave Swallows--would have southwesterly winds in advance of a long front that trails far down into Texas and northern Mexico. When these conditions occur in early November, Cave Swallows occur and often a smattering of other unusual species (Ash-throated Flycatchers, rare eastern warblers, etc.) crop up as well.

While a longer field of southerly winds might be nice, any westerly component connected to far away lands has a lot of potential to produce rarities. The wind fields should be almost continuous from the Great Lakes to the Northeast coast, so we might optimistically hope for some displacement of October migrant species from those areas. Some possibilities might be Le Conte's Sparrow, Sedge Wren, Say's Phoebe, Western Kingbird and (long shot) Smith's Longspur or Sprague's Pipit. Sandhill Cranes and rare geese like Greater White-fronted and Ross's could be in the cards. And in 1998 a somewhat similar system produced a massive East Coast fallout of Franklin's Gulls. While this system may be north of big concentrations in Kansas now (see eBird, of course, for current Franklin's flocks: http://tinyurl.com/5tqc22b), it is a species to think about. However, I think the 1998 system was significantly stronger, so if this storm does produce Franklin's, it is unlikely to displace the hundreds that reached the East in 1998

In any event, this is a heads up to get out birding despite the wind. I'll send some ideas in a subsequent email about where to go and how we might all coordinate our efforts a bit.


Marshall Iliff
Marshall J. Iliff
miliff AT aol.com
West Roxbury, MA
eBird/AKN Project Leader
Cornell Lab of Ornithology
Ithaca, NY

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