Report

Tricolored Blackbird Status Update and Management Guidelines

Date: 
2014-07-08

Ted Beedy and Bill Hamilton's 1997 report that summarizes a vast amount of literature and provided an update on the status of tricolors throughout their range up to 1997.

Breeding Survey of Tricolored Blackbirds in Baja California, Mexico, 2013

Date: 
2013-12-17

Jon Feenstra's survey during May, 2013 of 20 sites in Baja California, Mexico known or potentially suitable for occupation by breeding tricolors. Of these, only 3 sites were occupied and breeding was documented or suspected at all 3 sites. One of these sites was confirmed as a breeding location for the first time. Many sites were unsuitable due to sustained drought conditions.

Chronic Low Reproductive Success in the Colonial Tricolored Blackbird from 2006-2011

Date: 
2013-08-16

This publication by U.C. Davis ecologist Bob Meese, which appeared in the journal Western Birds in summer, 2013, summarizes the results of 6 years of field work designed to evaluate the role of insect abundance on tricolored blackbird reproductive success.

A total of 47 colonies was studied and relative insect abundance and reproductive success at each was estimated. In only rare instances was reproductive success estimated to be 1 young/nest or greater, and in each case higher reproductive success was correlated with unusually high insect abundance in foraging habitats surrounding colonies.

Tricolor reproduction appears to be food-limited and few locations in the Central Valley appear to have the abundance of insects necessary to support reproduction by a colonial insectivorous bird species.

Understanding the contribution of habitats and regional variation to long-term population trends in tricolored blackbirds

Date: 
2013-07-23

This new study by Emilie Graves, Marcel Holyoak, and Bob Meese of U.C. Davis and Rodd Kelsey of The Nature Conservancy (formerly with Audubon California) analyzes over 100 years of colony occupation data to help to understand the contributions of breeding habitats and regional variation to population trends in tricolored blackbirds. Temporal trends differed between breeding habitat types and were associated with regional differences in population declines. A relatively new nesting substrate, triticale (a wheat x rye hybrid grain), has since the 1980's produced colonies 40× larger, on average, than other breeding habitats, and contributed to a change in regional distribution since it primarily occurred in the San Joaquin Valley. The mechanism for such an effect is not clear, but could represent the local availability of foodstuffs in the landscape (i.e. stored grains) rather than something specific to triticale crops.

Results of the 2011 Tricolored Blackbird Statewide Survey.

Date: 
2012-06-01

This report, by Keiller Kyle and Rodd Kelsey of Audubon California, provides a summary of the 2011 statewide survey.

The Status of the Tricolored Blackbird (Agelaius tricolor) in Southern California: Results of the Spring 2009 Census

Date: 
2012-03-12

This report by Dr. Jonathan Feenstra summarizes the results of his efforts to estimate the number of tricolored blackbirds in southern California during the 2009 breeding season.

Nest Survival of Tricolored Blackbirds in California’s San Joaquin Valley 2011 Annual Report

Date: 
2012-03-07

Results of Kelly Weintraub's 2011 field season in the Tulare Basin determining the nesting success rates of Tricolored Blackbird colonies in various nesting substrates. This report was prepared for the Fish and Wildlife Service as an annual report.

Methodology, results, and discussion of Tricolored Blackbird nesting success are included.

Trapping and Banding of Tricolored Blackbirds in 2011.

Date: 
2011-10-06

Tricolors were trapped and banded at 4 locations in 2011 and hundreds of previously banded birds were recaptured. This report summarizes the trapping and banding results of U.C. Davis ecologist Dr. Robert Meese.

Reproductive Success of Tricolored Blackbird Colonies in 2011 in the Central Valley of California.

Date: 
2011-09-06

This is the annual report of Dr. Robert Meese of the Dept. of Environmental Science & Policy at the University of California, Davis and summarizes his field work in detecting, monitoring, and estimating the reproductive success of tricolored blackbird breeding colonies in the Central Valley of California. This report integrates 7 years of field work, provides evidence for insect limitation as among the factors causing the 35% reduction in abundance of tricolors from 2008 to 2011, and provides conservation recommendations that may help to sustain the species.

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