As I began to drive upward along one of the unpaved roads that meander through the Safari Park’s Biodiversity Reserve, the 800 acres California coastal sage scrub habitat situated next to the park, I realized two things. The first was that the height of the road I was on provided me a totally different perspective of our off-exhibit cheetah breeding area, an area where my team and I have spent thousands of hours studying cheetah behavior in order to maximize our breeding efforts of these majestic cats but whose overall size, for some reason, had thus far alluded me. This new view of all of the naturalistic enclosures together brought to mind new ideas of how we may be able to more effectively undertake introductions of potential cheetah suitors in the near future.
This contemplation, however, was soon replaced by a more immediate realization: I was en route to recording some of the native songbirds that call this California scrubland home and I’d forgotten my hat – a situation that on this unseasonably warm day, wasn’t going to bode well for someone as “follicularly challenged” (aka bald) as myself. No matter, the important thing was that I had remembered to refresh the batteries in my digital audio recorder and so was good to go for capturing the calls of two of the inhabitants of this area, the cactus wren and the mockingbird.
My plan was to sit in one of our hides and quietly observe (and hopefully record) what individuals of each species were doing and, more importantly, saying. As part of much larger, multidivisional effort based at the Institute, what I wanted to achieve on this visit was to ascertain if there were any specific characteristics of the mockingbird’s song that I could find that would help me to distinguish it from that of the cactus wren’s warblings. Mocking birds are notorious mimics and I wanted to make sure that in my later analysis of cactus wren calls (in relation to specific habitat usage) I wasn’t accidentally studying mockingbirds by mistake.
Over the course of several increasingly warmer hours of recording, I was suitably impressed by the mockingbird’s ability to copy cactus wren songs. However, what they were blissfully unaware of was that I was recording their every move (and utterance!) and had stumbled upon a flaw in their imitations. It turns out that at the very end of their version of the cactus wren’s song, mockingbirds simply can’t help but blurt out a cloud of expletives! It is as if there is a limit to how long they can concentrate on copying the notes customarily made by the wrens.
And it is this very mockingbird-specific section of their call that I have since taught our acoustic software to recognize so that I can be certain of whom I’m listening to!
This interesting finding is proving invaluable in helping with my long term remote monitoring of home territories of the cactus wrens. When I’m not able to be in the field, I have small, weatherproof recording devices listening around the clock on my behalf. Around the clock recordings from these amazing little machines are also helping us to better link wren behavior to ongoing efforts focusing upon re-establishing the Opuntia prickly pair cactus which provide these diminutive songbirds their preferred nesting sites.
Over the next few months I plan to follow the wrens throughout the breeding season to monitor how many pairs reproduce successfully during 2014. I have also made a note to self to make a concerted effort to always remember my hat and sunscreen in the future!
Matt Anderson, Ph.D., is the director of behavioral ecology.