Kent McFarland wrote:
> Ian's note about red-winged blackbird arrival dates is a good chance
> for me to plug (yes, once again) the use of eBird. Arrival dates over
> many years and a broad geographic range can be great for us to track
> potential climatic effects on migration.
> I took a look at the Red-winged Blackbird arrival dates from 1966 to
> 2004 for this data set. From 1966 to 1990 there is a trend toward
> earlier arrival dates at her house. From 1990 - 2004 the trend changes
> to a later arrival time. Anderson's data for Redwings showed a trend
> toward an earlier date of arrival, but it was not statistically
Your message was timely. Just the other day I entered the first
sighting date for Redwings, Grackles, and Robins into my perpetual
calendar which I started in 1987. As you described with K. Anderson, I
enter first sightings of some of the birds, lilac blooms, daffodils,
first wood frogs, etc. I was prompted to plot my Redwing data on a
graph and fit a trendline. For the years 1987 to 2006, there was an
overall increase but the R^2 was 0.21, not particularly meaningful.
However, when I look at the plot, from 1987-1992, there is a definate
tendancy for earlier arrivals. But since about 1992, the arrivals have
been increasingly later. Sort of mirrors what Kathleen's data showed.
I am going to plot the robin data later.