Thursday, March 26, 2015

Swainson's Hawks in Borrego Springs

Flock of Swainson's Hawks over Borrego Springs
Swainson's Hawks over Borrego Springs. This photo represents nearly the total
number of Swainson's Hawks I've previously seen in over 40 years of birding!
March 22, 2015. Borrego Springs, California. Greg Gillson.
Although a fairly common breeder early in the 20th Century, Swainson's Hawks no longer breed in southern California. Breeding widely in open country across western North America--even to Alaska, they form large flocks as they migrate to the pampas of Argentina for the winter.

In 2003 Hal Cohen moved to Borrego Springs from the Midwest, where he enjoyed many hawk watches along the shores of the Great Lakes. The West isn't famous for hawk watches like the East and Midwest, but Hal started counting migrating Turkey Vultures in his new home in late March. On April 11th he discovered about 1000 Swainson's Hawks coming into the Borrego Valley to roost at dusk. They fed on caterpillars in the morning, then departed as the thermals formed. It turns out this this is an annual event not previously discovered.

Borrego Valley Hawkwatch site tracks the comings and going of these birds. The official counts start February 15. Peak numbers are reached in mid to late March. The season ends on April 15. This website is great, because the blog tells you if, and how many, new birds entered the Valley that evening and where the roost is, and what strategy is best for viewing the next day based on wind forecasts. Over 9000 Swainson's Hawks were counted during the 2014 season.

Why are they here?

sphynx moth caterpillar

Yep. That's a caterpillar... and a big one, over 3 inches long. It is the caterpillar for the Sphynx Moth. There are literally millions of these juicy grubs crawling everywhere across the desert (see the tracks?) [not to mention the thousands squished on the roads!]. Why? Queue next photo.

desert flowers

In February there were rains on the desert and those seeds that laid dormant for months, or years, came to life. The moths laid eggs, and the caterpillars hatched and were hungry. The Swainson's Hawks took advantage. And the birders followed! (See this recent post on the Borrego Valley Hawkwatch site.)

desert flowers

I made a quick visit last weekend to Borrego Springs to locate some desert birds for my county year list. I was most interested in finding Crissal Thrasher in the mesquite there at dawn. I knew I could watch birds at the waste treatment plant and the Mesquite Bosque and be done mid-morning and still have time to possibly see Swainson's Hawks. They had been reported roosting in the evening near the landfill.

After birding the desert scrub I headed over to where the Swainson's Hawks were forecasted to appear. I noted cars parked on the side of Peg Leg Road and people in clumps looking through scopes and binoculars--birders!

Hawk watchers at Borrego Springs

There were still a few hawks in the field here, but most had lifted off--almost 150 were in the air, along with ravens and a few vultures. That's 3x the number of all the previous Swainson's Hawks I've ever seen--in over 40 years of birding! I snapped the photo that introduces this post.

The Swainson's Hawks will still be around for a couple more weeks. If you get the chance you should really check it out! I think I'll make plans for next year and take Marlene for a long weekend. Maybe I can get some closer photos of the hawks while they are still perched in their roosting trees or feeding out in the desert.

Tuesday, March 24, 2015

Black-bellied Plovers

Black-bellied Plover
Black-bellied Plover. Mission Bay, California. February 16, 2015. Greg Gillson.
I'm still going through some photos from Crown Point on Mission Bay from mid-February. Here are some to enjoy.

Back in September I photographed a Black-bellied Plover at the San Luis Rey River mouth. The black belly will start forming in April and May on the northward migration to the Arctic breeding grounds. Still there are a few black centered breeding plumage feathers on the back and scapulars of these birds poking through the browner non-breeding plumage of winter.

Black-bellied Plover

Black-bellied Plover

Saturday, March 14, 2015

Ruddy Turnstone

Ruddy Turnstone
Ruddy Turnstone. Crown Point, Mission Bay, California. February 16, 2015. Greg Gillson.
Here are a couple of pics from last month of a Ruddy Turnstone on Mission Bay. This bird is molting into its more colorful breeding plumage. These birds winter regularly in small numbers on Mission Bay at Crown Point Park. In Oregon I was only used to seeing them as fairly rare spring and fall migrants on the outer beach. It's nice to see them more often, now.

Ruddy Turnstone

Thursday, March 12, 2015

Who's bigger?

Short-billed Dowitcher and Black-bellied Plover
Short-billed Dowitcher (left) and Black-bellied Plover (right). Mission Bay, California. February 16, 2015. Greg Gillson.
If you look in a field guide you will see that the length of the Short-billed Dowitcher is 11 inches, while the Black-bellied Plover is 11.5 inches long--very close to the same. That's measured from bill tip to tail tip. Obviously the plover is a much larger bird than the dowitcher. But unless I see them together I never realize how large the plover is in comparison!

Even the long legs of the dowitcher--used to wade out belly-deep into the water--seems stumpy compared to the legs of the plover. However, the plover spends most of its time up on the beach, rather than wading. So they aren't often seen together like this for direct comparison.

The dowitcher is twice as long as the Least Sandpiper, and usually looks big compared to the other small shorebirds around it at water's edge.

Friday, March 6, 2015

Flexible bills

Dunlin flexible bill
Yawning Dunlin. Crown Point Park, Mission Bay, San Diego, California. February 16, 2015. Greg Gillson.
The bill of most birds is covered with a hard outer material. That would make sense for woodpeckers to drill dead branches, sparrows to chew the husk of seeds, and eagles to tear apart prey.

However, as you can see above, the Dunlin can bend its upper mandible slightly upward, opposite from its normally slightly down-curved bill angle.

I don't find a lot of information on flexible bills. In North America, other shorebirds such as snipe and woodcocks have notably flexible bills. The bills are able to feel below ground or water for worms and crustaceans that they eat.

The one bird in the world most noted for a flexible bill is the Kiwi, of New Zealand.

Here is the same bird a few moments later showing the typical bill shape.


Dunlin were also known in the past as Red-backed Sandpipers, as they have rusty backs in breeding plumage and most of the belly is covered with a large black patch.

A flock of Dunlin is evidently called a "fling." (Also a "flight" or "trip" of Dunlin.)


Tuesday, March 3, 2015

Come flop down on the beach with Black Skimmers!

Black Skimmer
A very relaxed Black Skimmer. Crown Point Park, Mission Bay, California. February 16, 2015. Greg Gillson.
There is nothing wrong with the Black Skimmer pictured above. They often rest with their heads on the beach like that! In fact, the Sibley Guide to Birds depicts one of the the birds exactly like this.

They are in an order of birds (Charadriiformes) that also includes the families of plovers, sandpipers, gulls, terns, skuas, and auks, among many other similar birds around the world. They all share skull similarities, webbed feet, and vocal structures.

But even though they are like these other birds, they are also different. Skimmers are just weird. They are very unusual--in many ways.

The lower mandible is much longer than the upper. They skim the water--and even the sand--with their bill as they fly slowly along with deep wing strokes primarily above the horizontal and head held down. As the bill contacts fish or crustaceans the head pulls back and then up as the bird swallows the food and then the head is dipped down again.

The eye of the skimmer has 5 times more rods than cones--enabling it to see well in low light conditions. Not surprisingly, they often feed at dusk/dawn, even at night, during low tides. However, since they often rest on bright sandy beaches in the sun, their pupils constrict greatly. Again, unique, their pupils contract in vertical slits like cats, and are not round as in other birds.

You may notice a metal band on the leg of the bird above. I think they are Mexican bird bands--they start with the word "Aves" (rather than "USGS"), and have some numbers, but I can't see the entire band to read it all.

Black Skimmer
A more respectable resting posture?

Black Skimmer
Is it my imagination, or do these look like horizontal penguins with Candy-Corn bills?

Black Skimmer
Short legs with webbed toes, but they rarely swim. Skimmers are just weird.

Black Skimmer
What's up with the nostril down on the side of the upper mandible rather than on top?

Additional photos from a post in December 2013 are here: Black Skimmers at Mission Bay

Monday, March 2, 2015

San Diego Bird Finding: Common Goldeneye

Common Goldeneye
Common Goldeneye. Imperial Beach, California. February 7, 2015. Greg Gillson.
It's a half mile walk northeast down the Bayshore Bikeway at 13th Street in Imperial Beach (site guide here) to the Salt Works Pond #20. But that's what it takes to find Common Goldeneye in winter in San Diego.

Single birds show up (often one-day-wonders) at ponds or in the bay every winter somewhere in San Diego County. But this is currently the only consistent location for multiple long-staying birds. Most are female or immature types, as in the distant documentation photo above.

Sunday, March 1, 2015

Birding Site Guide: Guajome Regional Park

Three dollars? Is that all that prevented me from watching birds in a large nearby park in Oceanside for over a year? The $3 parking fee? As Anthony Melchiorri says, "Are you kidding me?!!!

The first time I drove by Guajome ("wa-HO-me") park--just to check it out--the parking fee put me off. (That's what I get for taking off for a day of birding without any cash in my pocket.) Also, the parking areas don't open at dawn, so much of the bird activity has already ended by the time you can enter the park.

So I decided to check it out again 2 weeks ago. Marlene and I spent an enjoyable late morning there.

Guajome map

Getting there: 50 miles north of the I-8 & I-15 interchange in San Diego. Driving time and distance about the same taking either I-5 N along the coast or inland on I-15. Directions for I-5 N to CA-76 in Oceanside, then 7.5 miles east to Guajome Lake Rd. Directions for I-15 N to Econdido, CA-78 W to Vista, then take the Vista Village Drive exit, cross back left over the freeway, then turn right twice to go back under the freeway on S Melrose Dr for 3 miles, then left on N Santa Fe Ave for 1 mile and look for the day use parking lot. Parking: Two parking lots. $3 day use fee. Lower Parking Lot is day use only on N Santa Fe Rd south of Mesa Dr. The Main Parking Lot and campground is on Guajome Lake Rd. Hours: Day use: 9:30 am to sunset; camping 24 hours/day. Map navigation: 3000 Guajome Lake Rd, Oceanside, California 92057

Guajome map

Where to bird: Part 1: Upper Pond Loop

Starting at the day use parking area (A on the map above), walk the trail eastward, staying to the right for about 1/2 mile until you reach Upper Pond (B). When returning back cross to the north side of the creek until you reach C on the map, then return.

This loop is on the edge of dry upland areas and the reed-covered riparian area. Birds I found in mid-February on the first part of the loop included Cassin's Kingbirds, Lesser Goldfinches, and California Towhees. Just below the dam of the Upper Pond a Virginia Rail was calling, hidden in the reeds. Some Northern Shovelers were on the pond. And I photographed an Allen's Hummingbird there.

On the drier north side trail heading back to point C on the map there are several cacti patches. I found more Cassin's Kingbirds and several House Wrens, while American Kestrels and Red-tailed and Red-shouldered Hawks soared overhead.

Guajome Park
Day use area park (A on map). Guajome County Park, Oceanside, California.

Cassin's Kingbird
Cassin's Kingbird

Fence Lizard
Fence Lizard on a... fence post!

Guajome Park
South side trail leading to Upper Pond.

Guajome Park
Upper Pond (B on map)

Allen's Hummingbird
The hunch-backed Allen's Hummingbird

Guajome Park
North side trail on Upper Pond Loop.

Pricky Pear Cactus Guajome Park
Prickly Pear Cactus

Coastal Cholla Guajome Park
Coastal Cholla Cactus

Where to bird: Part 2: Campground Loop

There are perhaps more birds and less walking in the campground area of the park. The day use parking area by the campground (D on the map) is among California Live Oaks at the eastern corner of Guajome Lake. You can expect Nuttall's Woodpeckers and Hutton's Vireo there.

Walk down to the lake shore and follow it westward to E on the map. You should find many ducks, both wild and domestic. There are many domestic Swan Geese here. Great-tailed Grackles squeak and whistle.

There is a nature trail from E to C on the map, along the riparian corridor. Birds here include Marsh Wrens from the huge reed bed in the north end of the park. There were Common Yellowthroats and Orange-crowned Warblers during my February visit. Downy Woodpeckers are regular here--this isn't a very common species in San Diego County, but this coastal riparian habitat is favored.

When you reach point C on the map you have options of returning. I came back immediately opposite the outgoing trail, along the edge of the campground to the Gazebo on the hill, and back on the campground roads.

Guajome Park
Guajome Lake, south shore.

Guajome Park
Southwest corner of Guajome Lake.

Downy Woodpecker
Downy Woodpecker

Guajome Park
Nature Trail (E to C on map).

Cooper's Hawk
Cooper's Hawk

Guajome Park

Here is the eBird Hotspot page to check out recent birds at Guajome Regional Park.