Tracking Pygmy-owls Part III

4/8/15: Kate Stone helps with the observation efforts at the Pygmy-owl nest.
She searches for male #960 at 6:20 am. The bird appears to be north of the
nest, across a large drainage. At 7:00 am Kate hears soft high trills that we
correlate with the female vocalizations, but she cannot pinpoint its exact
location. The female continues to vocalize intermittently until the male starts
hooting in the vicinity of the nest at 7:16 am. This spectrogram taken from
the nest shows the typical male hoot and the female’s higher trill.

At 7:35 am the female perches east of the nest tree in the branches of a
nearby Douglas-fir (see picture below).

At 9:30 am Kate tracks the male to a large Douglas-fir, almost a kilometer
north from the nest, across Baldy Draw.

4/13/15: Kate is back at it. The male and female are going in and out of the
cavity and begin hooting and trilling at 6:39 am. The spectrogram below
shows the male hooting from the cavity entrance at 7:06 am, recorded by our
automated recording unit (ARU).

4/17/15: As soon as I arrive at the nest at 6:15 am, I start filming and swap
the ARU batteries. I see no activity, but when I review the footage later I
find the female sneaking into the cavity at 6:18 am. The exact time I was
changing the batteries. The entrance is so small that she gets stuck in the
hole for 5 seconds with her legs sticking out.

At 6:20 am the male’s telemetry signals are getting stronger. He is flying
closer to the nest, and at 7:51 am I start hearing male hoots. At 9:25 am, I
leave after failing to pick up any female activity.

In the afternoon I review ARU recordings from earlier that morning. I
witness peaks in Pygmy-owl vocalizations, as male #960 and its paired
female copulate twice between 5:58 and 6:11 am. Numerous copulation
events indicate courtship or laying stages. The ARU spectrogram below
depicts the copulation vocalizations. The yellow and white lines depict the
female and male range of vocalizations during copulation.

4/20/15: At 6:00 am Kate detects the male far to the northeast of the nest. It
is still dark, but she hears the female softly trilling for ten minutes east of the
nest. Between 6:20 and 8:24 am, the video recording confirms no activity at
the nest entrance. From 7:44 to 8:24 am, Kate hears three copulation
vocalizations and we speculate that the female might be laying eggs. In the
picture below, #960 looks straight at Kate, with his antenna still secured to
his back.

4/22/15: At 10:15 am, Kate, Sarah Norton and I go swap in a new battery for
our recording device and also peep into the cavity. The male transmitter
signals suggest #960 is away from the nest. At 10:38 am we observe three
eggs in the cavity!

Did you know that Pygmy-owls have a mean clutch size of 5 eggs, but they
can lay from 2 to 9 eggs? It takes on average 28 days for the eggs to hatch.

4/24/15: On another exciting note, Lewis’s Woodpeckers are returning from
migration. At 8:32 am our first Lewis’s Woodpecker of the year is caught on
camera thanks to Philip Ramsey.