Animal Conservation Projects

Population Dynamics and Conservation of Tricolored Blackbirds, Agelaius tricolor

I am interested in the population dynamics and conservation of Tricolored Blackbirds. Tricolored Blackbirds are the most colonial songbird in North America, and represent a conservation challenge because of their itinerant breeding and use of multiple habitats. The species is largely endemic to California (>99% of birds) with small populations in adjacent states and Baja California. The species is of conservation concern because populations have declined in abundance by an estimated 89% between the 1930’s and 1980’s. California experienced dramatic wetland losses, with a 91% loss between 1780 and 1980. Wetland loss and fragmentation are cited as the principle reasons for decline. Yet, the species has also shifted the kinds of habitat used for breeding, making it hard to know the role of shifts in habitat type in observed declines. My lab has worked with collaborators to analyze population trends, look at habitat usage and how habitat use varies with factors like rainfall. The species has also advanced its breeding by an average of 22 days between 1939 and 2009, which likely is an effect of climate change.  The work is funded by California Department of Fish and Game. The Tricolored Blackbird Portal was populated with historical data by my lab and provides more information about the species.


Collaborators includes

Rodd Kelsey, Audubon California rkelsey at

Bob Meese, Information Center for the Environment at UC-Davis,, rjmeese at

Emilie Graves, Wildlife, Fish and Conservation Biology at UC-Davis, eegraves at


Conservation of a threatened beetle

Male Tricolored Blackbird @ Marcel Holyoak.

A major research direction is the spatial dynamics of a threatened insect, the Valley Elderberry Longhorn Beetle, Desmocerus californicus dimorphus.

For further information about the beetle see Theresa Talley's website:

Field surveys were used to investigate the importance of different spatial scales for the persistence of this federally protected species, which is restricted to riparian habitats in California’s Central Valley. This project, in collaboration with Dr. Sharon K. Collinge (U. of Colorado), Jaymee T. Marty and Cheryl B. Barr (Essig Museum of Entomology, UC-Berkeley) demonstrated that local populations showed frequent turnover. However, at the watershed scale there was no extinction or colonization over 10 years (Collinge et al. 2001). Isolated sites were less likely to be occupied by the beetle. This is valuable information because it suggests that a watershed-scale approach is necessary for successful conservation.

More recent work in collaboration with my Ph.D. student Theresa Talley investigated the relationship between the beetle and its host plant, elderberry, which needs to reach a minimum size (and age) before being suitable for the beetle. When habitat is destroyed and new habitat is planted through mitigation there is a time period before the habitat becomes suitable; this ‘lag time’ means that even when habitat losses are well-mitigated there is a temporally substantial loss of habitat that could destabilize populations. We used habitat restoration, mitigation and natural sites to explore site age, the amount of suitable beetle habitat available and how this influences population presence and abundance. This project yielded both practical information about mitigation and habitat restoration practices and useful ecological information about a species which is puzzling because it persists at low densities. The results aid conservation by providing a scientific backing for conservation and management decisions.

Current and Past Collaborators on this work include:

Theresa Talley, University of San Diego tstalley AT

Gary Huxel, University of Arkansas ghuxel AT

Sharon K. Collinge, University of Colorado Sharon.Collinge AT

Description: Description: Description:
Male Valley Elderberry Longhorn Beetle, @ Richard  Arnold

Adult beetles are approximately 2 cm (3/4") long and are rarely seen.

Description: Description: Description:
Elderberry flowering,
@ M.Holyoak

The beetle feeds only on a single plant species, elderberry (Sambucus spp.).

Description: Description: Description:
A beetle exit hole in an elderberry stem
@ M.Holyoak

Beetles spend most of their lives burrowing inside elderberry stems. They leave distinctive emergence holes of 6-10mm diamteter.