A personal portfolio: A return to San Clemente Dam May 2006
all photos & text by Don Roberson,
except as otherwise indicated
all photos taken in California
In spring 1987, I was hired to do a bird survey of the Carmel River, Monterey County, from San Clemente Dam & Reservoir to the mouth. This 18.5 mile stretch was walked 3 times during May. I prepared a report for the Monterey Peninsula Water Management District, and the survey was incorporated into the Monterey Breeding Bird Atlas project (Roberson & Tenney 1993). Here (below) are a couple of photos from the report yes, they were taken in black-and-white back then of the Carmel River not far below San Clemente Dam. [and yes, the report was hand-typed on a typewriter; it's hard to remember those days actually existed . . .]
Because I also surveyed for 2 miles above the reservoir, I visited Cal-Am's property 5 times: May 2, 4, 5,7, and 14, 1987. Releases from the dam were comparatively minimal at the time, making for a nice rushing stream below the dam, along which I found and photographed a recently fledged American Dipper (left).

San Clemente Reservoir in May 1987 was very full (black-and-white photo below). Given this background, it was a pleasure to return to San Clemente Reservoir in May 2006, some 19 years since I las saw it. Today, the reservoir is heavily silted up (color photo below) and CalAm is keeping a heavy stream of outflow to reduce pressure on the dam.

On 14 May 2006, a group of 9 local birders conducted an informal survey of the area around the dam and downstream a couple miles. This outing was organized by Peter Spillett of Cal-Am. We had in-hand inventories made in December, and we supplemented the point counts in those efforts by using the VES and AES methodology.* Remarkably, we found fledgling American Dippers again; this time huddling just below the dam itself and visible from the viewpoint on the dam (shown at right).

We searched not only for birds, but a wide variety of wildlife and plants. Common butterflies included Silvery Blue Glaucopsyche lygdamus (below left) and Variable Checkerspot Euphydryas chalcedona (note the white dots on back of the abdomen; adult life span is 9 to 10 days only!). Brian Weed also recorded Lorquin's Admiral, W. Tiger Swallowtail, and Pale 

There were a wide variety of wildflowers, but we were most interested in this one (left), which grew in very moist spots on the shady, rocky slope. Jan Scott has identified it as Globe-Lily (or Fairy Lantern) Calchortus albus.

We had over 60 species of birds and much evidence of breeding. Near the upper bridge a pair of Warbling Vireo vigorously scolded a Steller's Jay that appeared to be eating an egg from their nest. Nuttall's Woodpecker, Song Sparrow, and Dark-eyed Junco were watched carrying food to be deliver to youngsters either still in, or just out of, their nests. The American Dippers were fledglings. We came upon several pair of Chestnut-backed Chickadees carrying food or with fledglings. I rather like the overall 'scene with chickadee' in a colorful sycamore (below left); this particular adult was quite agitated and vocal (below right) as it watched its mate carry food toward an unseen nest hole. I like this shot because it shows how dull the flanks can be in spring & summer in our local subspecies.

Certainly the most unexpected moment of the morning was when a bat flushed from under the lip of the dam and flew across a stretch of the reservoir to a vertical cliff (left). There is scuttled down along a deep crack until it crawled to a thinner crack and wedged itself in for the rest of the day. It appeared to be a small bat, and I initially thought it was likely in the genus Myotis, of which at least 7 species range to Monterey County: California Myotis M. californicus, Yuma Myotis M. yumanensis, Fringed Myotis M. thysanodes, Long-eared Myotis M. evotis, Long-legged Myotis M. volans, Small-footed Myotis M. ciliolabrum, and Little Brown Bat M. lucifugus. The environmental company that did Cal-Am's formal biological inventory used an Anabat unit to record the echolocation clicks of bats at night over San Clemente Reservoir. The computerized analysis of the data revealed the presence of two Myotis (Fringed & California) over the reservoir, as well as Hoary Bat Lasiurus cinereus. Elsewhere on the Cal-Am property, Big Brown Bat Eptesicus fuscus and Western Red Bat Lasiurus blossevillii were detected by the recorded echolocation clicks.
   Bat identification in the field is a new problem for me. Wilson & Ruff (1999) have detailed i.d. information plus photos of all species, as does Bowers et al. (2004), and Ingles (1965) has useful drawings and range maps. Hastings Reserve also has a nice on-line guide to central California bats and states what species have been recorded at the Santa Lucia Preserve, which is adjacent to San Clemente Dam. 
photo D. Roberson (this imaged has been substantially brightened) photo P. Spillett (this image left less retouched)
It is apparent from photos that our 'mystery' bat is not a Western Red nor Hoary Bat (nor any other large and distinctive bat in California), so it must be either Big Brown Bat, one of the 7 species of Myotis, or another small bat. Of the ones fitting our basic shape, Big Brown and 4 species of Myotis have been recorded at Santa Lucia Preserve (California, Yuma, Long-legged, Small-footed). Oddly enough, the Anabat survey had Fringe-tailed at San Clemente but it has not been recorded at adjacent Santa Lucia Preserve. There are apparently only a few specimens of Little Brown Bat from the county (none from Santa Lucia). I think we can easily rule out Long-eared and Small-footed: both have very pale pelage contrasting with black face and ears, unlike our rather dull, uniform bat. In looking at sketches and photos, our bat does not have anything close to the long, long ears of Long-eared, and seems to have too large a size of feet for Small-footed. I also think the foot size argues against California Myotis, as did the size of our bat. California Myotis is a quite tiny bat. My feeling was this was a small bat but not tiny; Big Brown is 30% larger and 50% heavier than any Myotis or other small bats under consideration, so I think Big Brown is out (also the feet seem too small compared to photos of Big Brown).
    This gets us down to four Myotis (Little Brown, Yuma, Long-legged, and Fringed), or maybe another small bat. So I sent the photo to two bat experts: Mark Stromberg at Hastings Reservation in upper Carmel Valley, and Chris Corben, the inventor of Anabat system (and also a bird expert). Both had rather startling replies. Both said that my photos were too poor to identify the bat but both said they could not rule Tadarida free-tailed bats [Mexican Free-tailed Bat Tadarida brasiliensis). This species has been recorded at both Santa Lucia Preserve and Hastings Reservation, and it is the species that roosts in Carlsbad Caverns, New Mexico, in the millions and is responsible for the famous dusk and dawn "bat flights" there. Chris wrote:
"I am not really convinced that Tadarida can safely be ruled out. Although Tadarida has a "free" tail, in most respects its tail is like that of other bats, it's just that the tail actually extends way beyond the edge of the membrane, while in other species, the tail only just extends beyond the edge of the membrane. Furthermore, the tail is often tucked back under the animal, so you often can't see it in a photo, and it can be hard to see in the field unless you are very specifically looking for it. In fact the dark-headed look could possibly fit Tadarida better than most species, which tend to look dark-masked but similar on the head to the back. But we are trying too hard!"
"Trying too hard?" Probably. But I got to looking at the photos again and, by gummit, in every shot that Peter and I have, there is rather thick nub at the what should be the tip of the tail. In photos of Myotis, the thin gets thinner and thinner within the attached membrane until it comes to a fine point just at the edge of the membrane. This bat seems to have a thick blob there, not a fine point. Could this be the "free tail" which is just "tucked back under the animal" as Chris says is common?  If so, a lot of other things fall into place. The overall uniform brown color fits Tadarida quite well and does not match the color pattern shown by any Myotis that occurs here (they all have blackish ears and/or masks contrasting with a paler pelage). And I think one can see the big round ears of Tadarida in Peter's photo (all the Myotis have more or less pointed ears).
    So I think our bat was a Mexican Free-tailed Bat a common species, perhaps, but one that gave me fits trying to identify. [And I still could be wrong. Chris Corben might lean toward Tadarida but he's not saying it was one.]
This final pic (right) is a shot looking down from the dam on a rainbow formed through the spillway mist. The rainbow ends at the base of the fish ladder. That fish ladder, we're told, is the tallest fish ladder in North America... it comes out near the top of the dam after making a switch-back curve. 

Here's the result of our VES/AES bird survey of 14 May 2006. Participants were Rita Carratello, Don Roberson, Larry & Carole Rose, Jan Scott, Peter Spillett, Rich & Nancy Trissel, and Brian Weed:

Canada Goose 3 pairs
Wood Duck 1 male flushed from Carmel River (RT)
Mallard 2 pairs
Common Merganser 1 male
California Quail heard near entrance gate
Mountain Quail heard near dam (RC); at their lowest known elevational range (the dam is at ~525' elev.)
Pied-billed Grebe one seemed to be sitting on a nest in reservoir
Green Heron 1 in flight at reservoir edge
Turkey Vulture ~8
Sharp-shinned Hawk 1 (RC) may suggest local breeding at this date
Cooper's Hawk 1 (LR) likely suggests local breeding
Red-shouldered Hawk 1
Red-tailed Hawk 2
Golden Eagle 1=likely foraging over the area; probably nests at nearby Santa Lucia Preserve
American Kestrel 1
Spotted Sandpiper 1=may nest on sandbars in reservoir
Band-tailed Pigeon 2=presumably breed here irregularly
Mourning Dove ~12
Great Horned Owl 1 flushed from day-roost along river
Anna's Hummingbird 7
Belted Kingfisher 1 male
Acorn Woodpecker 4
Nuttall's Woodpecker 8
Northern Flicker 3
Pacific-slope Flycatcher 10
Black Phoebe 5
Hutton's Vireo 4
Warbling Vireo 5 (incl. pair of adults agitated behavior to apparent Steller's Jay egg predation)
Steller's Jay 10
Western Scrub-Jay 10
American Crow 4
Common Raven 1 (RT) is quite unusual; this species has only recently been colonizing the Santa Lucias
Tree Swallow 2
Violet-green Swallow 7
N. Rough-winged Swallow 2
Barn Swallow 2
Chestnut-backed Chickadee 10 (CF & FL observed)
Oak Titmouse 10
Bushtit 25 (FL recorded)
White-breasted Nuthatch 1
Bewick's Wren 25 (CF observed)
House Wren 6
American Dipper 2 FL at dam
American Robin 2
Wrentit 5
Eurasian Starling ~15 around homes
Orange-crowned Warbler 12
Black-throated Gray Warbler 3
Wilson's Warbler 4
Western Tanager 1 in flight; may nest just upstream of reservoir
Spotted Towhee 20 (incl. CF & FL)
California Towhee 8 (incl. FL)
Rufous-crowned Sparrow 2
Song Sparrow 3 (incl. CF)
Dark-eyed Junco 15 (incl. CF & FL)
Black-headed Grosbeak 15
Lazuli Bunting 8
Brown-headed Cowbird 1
Bullock's Oriole 1 near entrance
House Finch  2 near homes
Lesser Goldfinch 1

61 species, of which 59 likely nest on or adjacent to Cal-Am property. [Specific breeding evidence noted is listed via Breeding Bird Atlas codes; e.g., FL=Fledgling, CF=Carrying Food, etc.] The exception are Western Tanager just a May migrant at this elevation and Common Raven. For the raven, no nesting is known anywhere near this vicinity and it may be a wandering bird. Several of these species were not present here in 1987, including Canada Goose, both Accipiters, and Wood Duck.

In May 1987, the following additional species were recorded in the survey area  (San Clemente Reservoir to the Filter Plant): All of these were likely breeders, except Double-crested Cormorant. 

Double-crested Cormorant = does not nest; thought a migrant on 2 May 1987
Northern Pygmy-Owl  heard in oak woodland adjacent to reservoir
Long-eared Owl   heard upstream of reservoir
White-throated Swift
Allen's Hummingbird
Downy Woodpecker
Hairy Woodpecker
Western Wood-Pewee
Ash-throated Flycatcher
Cliff Swallow  1 at the housing area
Brown Creeper
Canyon Wren  pair at the dam
Blue-gray Gnatcatcher  likely nested just above reservoir
Western Bluebird  pair at the filter plant
Swainson's Thrush
Yellow Warbler  nested near filter plant
MacGillivray's Warbler  likely nested upstream of reservoir
Red-winged Blackbird  nesting colony at reservoir in 1987
Purple Finch

Together, the May 1987 & May 2006 visits provide evidence of likely nesting of 78 species at San Clemente Reservoir or within 2 miles downstream. Wild Turkey, Barn Owl, and Western Screech-Owl also known from this site from other sources, bringing the local breeding total to 81 species. This does include a few birds that are restricted to oak woodlands surrounding the residential area and filter plant at the entrance (e.g., E. Starling, Bullock's Oriole, House Finch).

Butterfly identification from Bob Stewart (1997) Common Butterflies of California [West Coast Lady Press]
Tentative bat identification from Wilson & Ruff (1999) North American Mammals [Smithsonian Institution], Ingles (1965) Mammals of the Pacific States [Stanford Univ. Press], and Bowers, Bowers & Kaufman (2004) Focus Guide to Mammals of North American [Houghton-Mifflin]. I also thank Chris Corben and Mark Stromberg for their comments on the photographed bat.

* VES = Visual Encounter Survey; AES = Aural Encounter Survey. In other words, we looked around and listened . . .

All photos © 2006 Don Roberson.
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Page created 14 May 2006