cmyers's Identifications

This beautiful female Western small-footed bat was rescued n early September. It was brought into San Diego Humane Society Project Wildlife where an assessment found it was healthy. Project Wildlife volunteer team members cared for her to ensure she was well nourished and hydrated and able to fly well (in a fight cage). A diminutive species similar in size to a Myotis californicus, she weighed 4.9 grams at intake and 6.3 grams at release.
After passing all tests, she was transported back to Project Wildlife’s main campus in San Diego on 14 September for transport to a release site in the same general area as originally found. Volunteer Vryce and I met and found a suitable habitat in the background of a friend of mine who resides less than a mile north of recovery coordinates.
As per my standard practice, I set up an ultrasonic acoustic detector proximate in advance of release. Almost immediately another Western small-footed bat flew in and did a circle around me and my microphone, and stayed in the vicinity. A couple of minutes later fellow volunteer Vryce opened the transport carrier, the rehab transporter was opened, and the female gently removed and held out on Vryce's palm. She took off without hesitation.
The sonogram was recorded concurrently with release from Vryce’s hand. It shows a conventional MYCI sequence and what looks like a quick succession of social calls at half the normal MYCI frequency. The first screenshot (Image 6) is a compressed view. The second (image 7) is an uncompressed view that shows there was a series of acoustic pulses that when expanded show each was a series of very short duration, short interval calls. The sequence was also viewed in SonoBat (image 8).
It seems likely one of the two Western small-footed bats was communicating with the other. It isn’t possible to tell which one made the social call. Although purely speculative, it is fun to think the resident bat was a welcoming back party.