Rusty Blackbird Blitz - First Take
The first Rusty Blackbird Winter Hotspots Blitz (AKA Rusty Blackbird Blitz) was a smashing success! Thanks to everyone who participated. One of the intangible, but important, outcomes was a heightened awareness of the plight of this species and the desperate need for more information on its distribution and abundance.
Reports of rusty blackbirds are increasing, not because they have suddenly become common, but because more people are out searching for them. We are still receiving sighting reports and stories about rusties.
For the Blitz proper, E-bird has accumulated many sightings filled with interesting data and observations, and we are busy sifting through these to learn more about this mysterious bird. We will keep you posted on the results. In the meantime, we would like to share some summary statistics to provide a feel for how it all went.
Participation
173 birders submitted 453 rusty blackbird surveys under the E-bird Blitz protocol. Of these individual reports, 249 sightings totaling 19,243 individuals were recorded. 204 surveys did not record any rusty blackbirds (but negative data are very valuable as well). Some of these reports were repeats from the same site. The number of unique sites is 215.
Increase in Reports between 2008 and 2009
The number of rusty blackbird counts on E-bird greatly increased, probably largely due to the Blitz and the publicity surrounding the event. During the 7-16 February period, the number of counts increased from 70 to 262 between 2008 and 2009.
Comparison of number of rusty blackbird counts in February 7-16 for 2008/9
For the entire January/February period, reports rose from 436 to 718. We suspect that the publicity for the Blitz contributed to this overall greater reporting of rusty blackbirds.
Comparison of number of rusty blackbird counts in January/February for 2008/9
Distribution
Rusty blackbirds were reported from 27 states (see map) with extra-limital sightings from Washington, California, and Alaska (photographed at Seward!) The following states produced sightings at 10 or more sites:
- Ohio
- Arkansas
- Virginia
- Mississippi
- North Carolina
- Alabama
- Georgia
- Tennessee
- Kentucky
- Missouri
- Maryland
- South Carolina
In general, these states fall within the known core winter range of the species, but the details of how states ranked is sometimes surprising. For example, the very high value of Ohio when compared with states further south does not conform well to our pre-conceived notions about winter rusty blackbird distribution.
Number of counts by state
We will not go into detail about these apparent anomalies, except to say that these numbers reflect the number of birders participating in the Blitz as much as the actual frequency of the species.
As we plan and conduct future surveys, we may want to consider ways of increasing participation in areas where rusty blackbirds are relatively common and birders are relatively rare.
Abundance
Because repeated surveys were taken from the same location, we analyzed the data using the maximum reported per site. The state-wide mean for the number per site does not correlate at all with the number of sightings per state. This value may provide a better measure of overall abundance. In this case, the highest mean counts were found in the states of the Lower Mississippi Alluvial Valley including Tennessee, Mississippi, Arkansas, and Alabama averaging over 100 birds per site.
The next tier (50 or more per site) includes two states along the South Atlantic Coastal Plain and adjacent Piedmont (North and South Carolina) and two more states in the greater Mississippi Valley (Missouri and Louisiana). The following gives the mean number in descending order for the 27 states:
In some states, a few very large flocks (see Super Hotspots below) skew the average number considerably. The median number per state gives a more reasonable assessment of overall abundance at sites where rusties were found. Using the median, the states with the largest average number are similar, but Tennessee, Arkansas, and Louisiana drop considerably in rankings.
Rusty Hotspots
The average maximum count per site was a surprisingly high 98. However, this number is highly skewed by some very large counts (hotspots) and the median count was 13.
- 47% of the sites produced maximum counts of 10 birds
- 33% of the sites had 50 or more birds
- only 13% of the sites had over 100 birds
The 48 sites with 50 or more rusty blackbirds were concentrated in a few states. Browse the map at the bottom of this page to see the counts at each individual site.
States with sites of 50 or more rusty blackbirds
- Alabama and Mississippi (8)
- Arkansas (7)
- North Carolina (4)
- Tennessee, Kentucky, and Virginia (3)
Super Hotspots
Approximately 3% of the sites had a maximum count of more than 500 individuals. These few spots, because of the outstandingly large numbers, should be mentioned individually. We need to sort through which of these sightings represented concentrations at roosts and which were feeding aggregations.
The high count of up to 5,000 reported for a pecan orchard in western Tennessee. Other large concentrations in the south central region were found at:
- Black Swamp WMA (2500)
- Searcy Bike Trail (1500)
- Panther Swamp NWR in Mississippi
- Wheeler NWR, Alabama (500)
High counts along the Atlantic coastal states include:
- 300 at Lake Conastee near Greenville, SC
- 300 in Tanglewood County, NC
Future Analyses
The reports have much more to tell us and we are plowing through the comments fields to learn about specific flock size, sex ratios at different sites, and habitat conditions associated with hot spots. We also need to distinguish between foraging and roost or staging sites. As we complete these analyses, we will update you on what we have discovered.
Sightings Map February 7-15, 2009
Legend
 | 1-49 birds |
 | 50+ birds |
Click on the icons to view the exact count
Use the + and - buttons to zoom in and out of the map and the Satellite and/or Hybrid buttons to view detailed land cover images.
Listen to its song
