April is a good month for getting a bit batty
Since most of us are diurnal, we are often more aware of the bird than of bats. This April, consider taking a twilight drive to Point Reyes to check out the maternity colony of Yuma myotis at the Red Barn.
Yuma myotis is a mediumsized bat of the west, ranging from British Columbia to Mexico. It has a 9-inch wingspan. Like all our local bats, Yuma myotis eat insects. They prefer soft-bodies insects like moths, froghoppers (which you may know in their larval form when they are called spittlebugs), leafhoppers, ground beetles, midges, mosquitoes, house and stable flies, caddisflies and crane flies (often called “mosquito eaters” even though they don’t eat mosquitos).
Although these bats mate in the fall, they store sperm and do not ovulate until spring. (If they don’t have enough fat, ovulation does not occur.) They give birth to a single pup in May.
The California dogface is named for the yelloworange profile of a dog’s face visible — if you have a good imagination — on the upper side of the black forewing of the males.
Plan to arrive before dusk at the Red Barn at the junction of Bear Valley Road and the Bear Valley Visitor Center Access Road that goes to the visitor center. Then watch as the female bats that roost there appear and set off to hunt for insects. While their echolocation calls are in the 47 to 55 kilohertz range, well above human hearing capability, they also have social calls that are audible to humans.
If you want to explore the world of bats more seriously, there are now small devices that plug in to the lightning port of an iPhone or iPad that can detect and identify bat sounds.
Another good place to look for bats at Point Reyes at dusk is Five Brooks Pond, about five
miles south of Olema on Route 1.
Do you know your California state insect? The California dogface is named for the yellow-orange profile of a dog’s face visible — if you have a good imagination — on the upper side of the black forewing of the males. They are not common in Marin because the host plant California false indigo or mock locust is not common. Right now it is leafing out, so it will soon be easy to spot. Two good places to see the host plant, and have a chance to see the butterfly, are Olompali State Historic Park north of Novato on the Loop
Trail and Kent Pump Road, which departs from the Alpine Dam.
Note that you won’t see the dogface on males when the wings are closed, and that females are yellow and do not have the “dogface” on their forewing though they do have a black spot where the eye of the dog is on the male. Bring binoculars and/or a telephoto lens, since neither state parks or Marin Municipal Water District allow netting butterflies.
Pigeon guillemots are related to the better known puffins. They are unusual in that they winter north of Marin, in Washington and British Columbia, and return to Marin to breed in the spring. Males return first,
followed several weeks later by females, so usually it is males that choose a nest site.
In breeding plumage, pigeon guillemots are dapper black seabirds with bright red legs and feet
and white wing patches. They nest in rock crevices and cracks, and holes in human structures like wharves, where the female lays one or two eggs. They share in incubating the eggs and feeding the
young fish. The young can swim and dive before they can fly.
Look for pigeon guillemots from now until August at Chimney Rock at Point Reyes, especially around the docks. Alcatraz Island, which partially reopened on March 15, is another great place to see them. They may even be swimming around the pier where the ferry docks. While you are there, you can also enjoy nesting pelagic and Brant’s cormorants, western gulls and other birds.