Date: 10/22/19 3:46 pm
From: <whoffman...>
Subject: [obol] Re: Oregon Birds and Slender-billed Nuthatches
Thanks, Joel -

For the correction of my inadequate description of oak habitats for nuthatches. I was certainly not advocating for focusing on ash habitats INSTEAD OF oaks, but rather in addition. And thanks for also describing use of large cottonwoods.

One point I particularly wanted to make is that when Oregon Ash stands reach an age where foresters would call them "decadent" the number of cavities and cavity-nesting birds they host can be really impressive. On a summer visit to the Kiwa Trail at Ridgefield NWR about a decade ago, I saw, Violet-green Swallows, Tree Swallows, Bewick's Wrens, Slender-billed Nuthatches, and Black-capped Chickadees, all apparently territorial within the ash stand. I do not remember which woodpeckers were there, but most of the other birds seem to be associated with natural cavities where branches had broken from the trunks. On another trip another birder pointed out a Great-horned Owl chick in a large cavity where a 10" branch had broken and rotted out. I do not know whether anyone has systematically documented cavity abundance, but those woodlands impressed me.

As to Finley NWR, many years ago and long before the boardwalk was built, I was able to wander around in the creek bottoms in summer, and regularly found nuthatches.

Wayne


From: <clearwater...>
To: "obol" <obol...>
Cc: "whoffman" <whoffman...>
Sent: Tuesday, October 22, 2019 5:38:16 PM
Subject: Re: Oregon Birds and Slender-billed Nuthatches

Hi Wayne and all,

For starters, just to be clear I should note that Slender-billed Nuthatches
(treated as a subspecies of White-breasted Nuthatch in most references) are
strongly associated with open oak woodlands as well as oak savanna.

The difference between these habitat types is gradational and definitions
vary, but roughly speaking, "savanna" has very widely spaced trees with 5%
to 25% canopy cover, while "woodland" implies >25% canopy cover. Somewhere
above 50% canopy closure, the growth form of oaks becomes more vertical and
less suitable for these birds, per research by Karen Viste-Sparkman, Joan
Hagar, Bob Altman and others.

I agree that Slender-billed Nuthatches can be found in other habitats. I've
found also found them with some regularity using big old cottonwoods in the
North Unit of Luckiamute State Natural Area (the "Luckiamute Landing" tract
of LSNA). There are no old oaks in that unit of LSNA, but there are some
nice, savanna-grown oaks just across the Luckiamute River (the Baker tract).

Slender-billed Nuthatch pairs have fairly large territories (likely >10
acres and possibly as much as 40 acres), so it could be that these birds
are spending part of their time across the river. There is also an Oregon
ash component in both the Luckiamute Landing and Baker tracts.

The south unit of Luckiamute SNA (Vanderpool Tract) is another place where
you can regularly find Slender-billed Nuthatches in bottomland Oregon ash.
However that's an even more complicated situation: Oaks and ashes are
intercalated in a "tiger-striped" kind of pattern, with oaks on the well-
drained ridges formed by old gravel bars, and ash trees in the swale in
between. The nuthatches there seem to spend more of their time in the
oaks.

The case of Muddy Creek at Finley NWR is somewhat similar. It's been a
long time since I walked the Homer Campbell boardwalk out to Cabell Marsh,
which I suppose is the area you're talking about. But there are large oaks
immediately adjacent to the bottomland ash. From Google Earth images,
there also seems to be a substantial strand of large oaks running through
the ash forest, perhaps not visible from the boardwalk but coming within
50-100 yards.

I'm not familiar with the situation at Ridgefield NWR so hopefully others
can comment. I recall that this has come up in previous discussion of
these birds. Downtown Eugene has been mentioned as another place where
Slender-billed Nuthatches occur away from any significant stands of
Oregon white-oak.

Generally I agree with you that it's good to recognize the value of
these secondary habitats (I'd include "old-growth" cottonwoods on the
list along with old Oregon-ash).

As you note, these secondary habitats are perhaps even more scarce than
open oak woodlands/savanna. So recognizing that nuthatches use them should
not detract from the need to preserve old, open-grown oaks.

All the best,
Joel

From: whoffman@xxxxxxxx
To: obol <obol@xxxxxxxxxxxxx>
Date: Tue, 22 Oct 2019 13:27:29 -0700 (PDT)

Hi -

I just received my Oregon Birds. I guess it takes a couple more days for it ti
cross the country. Anyway it looks great. An issue to be proud of.

I am writing because I just read the Slender-billed Nuthatch article, and I
have a quick comment. The authors describe the strong association between these
nuthatches and Oregon Oak. This certainly is where theswe birds are most often
seen, but I have found them too often to be incidental in one other
northwestern habitat: Riverbottom stands of Oregon Ash. These habitats are less
common than oak savannas, and perhaps more reduced as well, but where they have
been allowed to grow old, they harbor impressive numbers of natural cavities,
and large populations of cavity-nesting birds. I will mention 2 places where I
have encountered Slender-billed Nuthatches regularly in these stands.

First is along the auto tour route in Ridgefield NWR. In particular, the ash
stands along the Kiwa (sp?) Trail, and the stands along the tour route just
beyond the trail. Do others' observations square with this?

Second is along Muddy Creek south of Corvallis, including in Finley NWR.

IMO these ash bottomland stands are worth preserving/restoring for many
reasons, but for nuthatches as well.

--
Joel Geier
Camp Adair area north of Corvallis

 
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