Wednesday, October 21, 2009

A Personal eBird Milestone

Yesterday I reached a personal milestone in my eBird usage. One of the features that makes eBird such a compelling site is that the ability to set up personal birding locations and generate bar charts and other abundance graphics for them. If you have a local patch, this feature makes it possible to monitor how many species you have seen at the location and when individual species have arrived or departed in the past. It also provides some additional motivation for birding there. Each new checklist makes the chart more complete and adds better abundance data to make it more useful. As Nate wrote, the charts start to look like real abundance charts in a very short time.

Bar charts are divided into months, which in turn are divided into quarters that more or less correspond to the weeks. (The last "week" in each month usually has more than seven days, since it stretches from the 22nd to whatever day the month ends, whether that be the 28th, 29th, 30th, or 31st.) Each checklist either fills a new week or adds sightings to a week that already had data. The bar chart can pull checklists from as many years as you want; the default is 1900 to the current year.

After I did my usual bird walk in my local patch (Donaldson Park) yesterday, I entered a checklist and checked the bar chart for the location. That checklist had filled the last remaining gap on the bar chart for my local patch, so that now every week of the year is represented by at least one checklist. The top portion of the bar chart is below; click through for a screenshot of the full page and species list.

Over the past few years I have recorded 132 bird species in the park. The only species I have recorded for every week of the year is Canada Goose. I have seen other common species like Mallard, Ring-billed Gull, Herring Gull, Great Black-backed Gull, Mourning Dove, American Robin, European Starling, Song Sparrow, and House Sparrow during most weeks but missed them occasionally. There are also a few species like Killdeer that are present on almost a daily basis for most of the year but depart for a few months at a time. The list also includes a few relative rarities like Iceland Gull, American Pipit, and White-crowned Sparrow.

My bird walk yesterday included a mix of the regular birds and some migrants. The best bird was a White-crowned Sparrow at the east end of the park. It was only the second time I have seen on in that park, or in the county. There were also small flocks of Savannah Sparrows, Yellow-rumped Warblers, and Chipping Sparrows, in addition to a few Ruby-crowned Kinglets. In some ways the most impressive sight was a huge flock of Herring Gulls, a little under 800 strong by my estimate. Especially with such a beautiful afternoon, this walk turned into a great way to fill the last gap.