Subject: Re: Rufous-necked Stint Article
Date: Jul 10 16:33:31 1995
From: Alvaro Jaramillo - alvaro at quake.net


Thanks for the info Michael.. I have not gotten my issue yet.

>On July 04, Al Jaramillo said:
>
>> In my mind, this Rufous-necked Stint arrival bit is a really good
>>question. What I would like to know is if the pattern of late June/early
>>July arrival is real or an artifact?
>
Michael Price replied:

>It's real; although the migration period is spread all over hell's half
>acre, but if you average all this stuff out, you get a *general*
>arrival/peak of July 13. I'm sure my crude calculations can be refined
>*much* more; i.e., average arrivals for each location on the Coast.

I compared the info to Dennis' data in Shorebirds of the Pacific Northwest
for Western Sandpiper and in fact this info suggests that Rufous-necks are
not earlier than westies. Peaks for Western Sandpiper occur in early to mid
July. This conflicts with mine and your understanding of the situation,
aren't large samples great?

>>So why do Rufous-necked Stints migrate through early? I have two guesses:
>>1) They are most obvious early in the season. In June and July Rufous-necked
>>Stints should show a good amount of red on the plumage which makes them more
>>obvious. Later on they will be more faded and duller and perhaps will have
>>started moult.
>
>Hey, we shorebird hotshots in Vancouver BC have yet to see a wussy
>Definitive Alternate male (Prater et al., says females paler) RNST anyway!
>They've all been in Alt 1 or pre-basic molt, probably the former. We *like*
>hard ID's! The table from Escott's article shows RNST's not all that early,
>but similar to WESA and Semipalmated Sandpiper.
>
>PS: Al J asked:
>>Michael, I'm curious but how were you identifying the First Alternate
>>(young) from the Definitive Alternate (adult) birds?
>
>By late June--mid July, any WESA is going to be showing as much alternate
>plumage as it's gonna be showing all year, pre-Alternate molt (including
>"fresh" Alternate) being pretty much over by then, I think, so if it's not
>showing a fairly complete version of Definitive Alternate by then, it's
>*probably* an Alternate 1 bird. And being at the N end of WESA wintering
>range, I'd guess that many first-return birds don't have far to come back.
>
I agree with you, but to be certain of the age you should be looking for
heavily worn primaries. As I understand it, most peeps in first alternate
obtain a substantial to complete alternate plumage, much more so than larger
shorebirds. As well, in many shorebirds the amount of alternate that they
obtain is related to how close they get to the breeding grounds, so what a
first alternate looks like is really variable. The primaries are much older
on a first alternate bird than on an adult, so they serve as a more clearcut
way of ageing the birds. I imagine that the extent of the prealternate moult
is also variable in adults, so that a small minority will show some 'basic'
feathers on the plumage. My experience looking at shorebird photos and skins
is that this is often the case. So to be sure of your ageing, you should
confirm it with the worn primaries.

Alvaro Jaramillo
Half Moon Bay, CA

alvaro at quake.net