May 26, 2004
More mud-walking
In between birding trips, I have been known to do the occasional bit of work! I'm working as a postdoc at UC Davis, developing mathematical models for the invasion of hybrid cordgrass (Spartina foliosa x alterniflora) in San Francisco Bay. One of the things that attracted me to this job was the opportunity to interact with ecologists and molecular biologists, and I'm even allowed to help out with the fieldwork occasionally!
Yesterday I joined Christina, Debra and two Heathers in the ambitious task of attempting to locate every hybrid seedling at Roberts Landing. I had the 'honour' of carrying the oldest GPS unit, which consists of a hand-held unit connected to a backpack holding the battery and antenna - I ended up looking like one of the Ghostbusters!
So, why do we care about the presence of hybrid cordgrass? Firstly, hybrid seedlings are much more likely to become established in the open mud than the native foliosa:
Once established, the hybrids grow rapidly into dense circular clones:
As well as covering areas of open mud vital to feeding migratory shorebirds, large clones accumulate sediment, changing the tidal height:
Add to this increased pollen viability and self-compatibility, higher tolerance to disturbance and salinity, and a lack of natural grazers compared to the native, and we have a problem on our hands!
Shorebirds seemed scarcer than on my last visit, although I still saw a few Long-billed Curlews, Marbled Godwits and Dowitcher spp (I think Short-billed but they didn't call). Highlight was a fly-by Elegant Tern (in addition to the usual Caspian and Forster's), another lifer! As we prepared to leave, this territorial male Anna's Hummingbird was singing from his favourite bush.
