Date: 11/13/17 5:49 pm
From: Pam Hunt <biodiva...>
Subject: [NHBirds] Absence of birds?
Greetings all,



The question of "why are there no birds around" has been coming in to NH
Audubon, NH Fish and Game, and presumably our colleagues across the river in
Vermont, for most of the fall. Seeing as how it just exploded somewhat on
the UV Birders email list, I finally decided to do a little analysis, and
share the results with folks on both that list and the bigger NH.birds
google group.



Our line at Audubon, and one repeated by several folks on UV Birders, is
that a combination of a mild fall and abundant natural food crops has
reduced the "need" (perhaps "inclination" is a better word?) for birds to
visit feeders, and people with feeders are the source of much of the
concern. That said, there have certainly been times when birds also seem
scarce away from feeders as well. The most obvious way to study this
question a little more thoroughly is to look at some data, and in this case
we have an excellent (if I say so myself) dataset with which to work.



In 2005 I moved to Concord, and as those who know me know, I have a tendency
to establish long weekly bird survey routes wherever I live. The "Penacook
Survey Route" was established in August of 2005. It is a 10 km walk and
passes through a mix of forest, wetland, low intensity housing, a couple of
condo complexes, and along a river. I survey this route weekly all year long
(weather and presence permitting) and thus have a wealth of data with which
to answer questions about variation in species phenology, diversity, and
abundance over time.



I extracted the data on 12 common birds for the last 13 falls, focusing on
the period between Oct 1 and Nov 15. For each species, I calculated the
AVERAGE number of birds each year for that 6 week period, and then plotted
that number on a graph by year. I also calculated the average of the
previous 12 years (I'll call it the long-term average) for direct comparison
to 2017.



A picture may be worth a thousand words, but unfortunately I can't/shouldn't
send these graphs to the lists, so a bit of text will have to suffice. I'll
give each species a line or two summary.



1) Mourning Doves go up and down quite a lot since the species is
partially migratory. The long-term average is 5.34, this year it's 5.8. Last
year was near a record low at 2.2.

2) Downy Woodpecker is actually showing a very slow overall increase.
They are down a little this fall (4.8) compared to the long-term average
(5.84)

3) Hairy Woodpecker hovers right around 5 (4.94) and like the Downy is
a little lower this year (4.2).

4) Blue Jay is a species that can vary A LOT depending on accord crops,
and it's also partially migratory. Despite this, numbers are pretty
consistently near 20 (19.92), and the current season finds them at 19.2.

5) Black-capped Chickadees DO show a pretty consistent long-term
decline (which I think is present in other data sets), but are still
abundant. The average for 2017 is 25.4, vs. 31 for the long term. The
average was 29 for the last two years, after a record high of 44 in 2014.

6) Most folks know that Tufted Titmice are slowly increasing, and this
also the case for the Penacook Survey. This year: 13.2, long-term: 13.02.

7) The longer trend for White-breasted Nuthatch is an erratic increase,
but the last few years have shown a drop. The highest was 13 in 2014 and
they're now half that (7.4). The long-term average is 9.

8) I expected White-throated Sparrow to show some noise, and it
certainly did (range is 10-82). That low of ten was actually just last fall,
and this year they're at 35.2 as compared to the long-term average of 34.7.

9) Dark-eyed Juncos are also highly variable, since the numbers I get
in Penacook are entirely non-local birds. They are down significantly this
year (25) compared to last (74) and the long-term (55). Given the mild fall,
many could still be farther north - or there are just fewer of them. Junco
populations seem to follow a rough two-year cycle.

10) Northern Cardinal is a little like the nuthatch: slowly increasing
with a bit of dip this year: 6.8 in 2017 vs 7.3 for the preceding 12 years.

11) House Finch actually surprised me a little. This non-native was
severely impacted by Salmonella in the mid-1990s, and NH populations dropped
like a rock and stayed stable but low ever since. They are steadily
increasing on the Penacook survey however, and hit a record high of 18.6
this fall, compared to the long-term average of 8.7.

12) Last but not least, I expected American Goldfinch to be the most
variable of the lot, since it has a definite two-year cycle in winter data.
Not so in the late fall, however, when the data show a pretty tight range
between 15 and 25. Long-term average is 21.2 while for 2017 it's 21.0. Now
I'm curious whether the two-year cycle shows up in the WINTER data for
Penacook, but THAT analysis is not the subject of this email!



Put all this together, and the majority of species in this subset are stable
or increasing, albeit often with a high degree of variability. Is this
pattern the same everywhere? Certainly not, since innumerable factors
influence bird populations at all manner of spatial and temporal scales.
However, I have no reason to believe that my little corner of NH differs
radically in any major way from anywhere where other birders are looking.
How it MAY differ is in that I have a long-term standardized data set that
covers a fair bit of territory. Based on this I simply cannot support any
conclusion that birds have declined dramatically and that there is something
going on we should be worried about. With luck, your local birds will
eventually find your feeders or favorite haunts. Or not, they kinda tend to
do what they want!



In the meantime, enjoy what you can find and perhaps save a little money on
bird seed.



Pam Hunt

Concord, NH





"The most dangerous worldview is the worldview of those who have not viewed
the world."

- Alexander von Humboldt



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