Maeve's comments and link (below) about suffering woodcocks got me
thinking about previous years.
Below is the recent history of the arrival of American Woodcocks each
spring from 2006 to this year as recorded in eBird. Four items of
interest are tabulated. Using weekly data, of interest are the dates of
the first birds to arrive, the peak of woodcock numbers (which is very
shortly after the first birds arrived and displays are at a max),
whether numbers increase continuously to that peak or if there is a gap
or other setback such as we are experiencing this year, and are the
arrival and peak numbers revealing a climatic warming.
I don't know about other observers, but I monitor the woodcock site at
our home on the southern end of Snake Mountain daily for the 10 minutes
before and after the beginning of civil twilight each morning, and the
for the 10 minutes before and after the end of civil twilight each
evening starting sometime in early February. Those times are the
transition moments for our eyes switching between rods and cones, and
when we switch between having difficulty doing ordinary visual tasks
(because of darkness) and having sufficient light. The light sensors of
the woodcocks are coded for that time as well, and it is the most likely
time to hear them.
First, what do we know so far this year? Is it like some earlier years,
or a new pattern?
2017: February 25-26 --- the first arrivals; 3 locations, 4 birds
March 1-2 --- 2 locations, 2 birds
March 6-10 --- 6 locations, 7 birds (the last time
woodcocks were recorded; today is March 18th)
2017: First birds --- February week 4. Gaps till ?? Peak --- ??
2016: First birds --- March week 1. Peak --- March week 4.
2015: First birds --- March week 4. Peak --- April week 2.
2014: First birds --- March week 1. Gap of 2 weeks. Peak ---
April week 1.
2013: First birds --- March week 1. Peak --- April week 2.
2012: First birds --- March week 1. Peak --- March week 3.
2011: First birds --- March week 2. Peak --- April week 1.
2010: First birds --- March week 2. Peak --- March week 4.
2009: First birds --- March week 3. Peak --- March week 4.
2008: First birds --- March week 1. Gap of 2 weeks. Peak ---
April week 3.
2007: First birds --- March week 3. Peak --- March week 4.
2006: First birds --- March week 2. Peak --- March week 4.
The first week of observation from 2006 to 2011 is mid-March except for
one year when it was the first week.
The first week of observation from 2012 to 2016 is the first week of
March, except for one year when it was the last week'
The first week of observation for 2017 was the last week of February.
So these crude data show a trend toward earlier arrival of woodcocks.
Three of the 12 years (25%) have gaps in arrivals, probably all being
weather related; this year clearly has had early thaws interspersed with
hard frosts and several days in a row staying below freezing ... plus
Stella the Nor'easter. Not anywhere are there enough data to talk about
trends or not. However, for those 25% of the years it is likely most of
the early arrivals will not survive.
Peak dates are all during the last week of March or sometime in April,
but no trends of change are emerging. With the peak dates so close to
the beginning of migrations, the migration can be characterized as a
wave of birds all moving at the same time, with a few individuals
dispersing northward well in advance of the wave.
From these data, It would seem that American Woodcocks are not locked
in to just day-length triggers for migration, but are responsive to
temperatures and perhaps more complex weather/climate factors. If so,
that responsiveness may be a boon for the species during a period of
global warming. I'm sure there is a large literature on this topic for
the species. But for now, this little exploration is done.
On 3/18/2017 2:19 PM, Maeve Kim wrote:
> Hello. everyone - A fellow birder and participant in some of my classes just sent this, forwarded from NJ. Woodcocks are just beginning to get to Vermont. Maybe we VT birders can help a few of them! - Maeve Kim, Jericho Center
>>>> Winter Storm Stella - Tough on Birds.
>>>> With the unusually warm weather in February and early March, many migratory birds returned to our area early. Then Stella arrived.
>>>> Particularly hard hit has been the American Woodcock. This Nerf football of a bird eats a diet almost entirely made up of earthworms.
>>>> With this hard snow cover, Woodcocks are starving, failing and in distress in huge numbers. In the last 48 hours we admitted more Woodcocks at The Raptor Trust than in the entire 2016 calendar year.
>>>> If you find one of these rotund worm-eaters, please do everything you can to get it into a box quickly, keep it warm, and get it to a licensed wildlife rehabilitator as soon as possible.
>>>> Having just returned from their wintering grounds in the Southern United States, the Woodcocks arrive in our area thin, stressed and very hungry after hundreds of miles of in-flight migration. That they have arrived to find no food has compounded the problem for them.
>>>> Again, if you find a struggling Woodcock, please do what you can to get it to a wildlife rehab facility.