Date: 3/30/18 2:30 am
From: Thomas Wetmore <ttw4...>
Subject: [MASSBIRD] Plum Island "Commoness Chart"
PI Birders,

Let me call your attention to one of the pages I update on the Plum Island Birds web site nearly every day. I call it the "commoness" chart. It lists all the birds seen on Plum Island that are in my sightings database, ranking the birds by how many days they've been seen on the island since I started the database (so all sightings are from 2002 and later).

This can be a fun chart to check, especially for the more competitive, since we can see which bird is ahead of which bird in the sightings "race". I also color code any changes that have occurred on any given day, making it easy to spot the latest changes. Here is the location of the chart:

Since I update this chart almost every day, any comments I make on its exact contents apply only to the latest version. But if you look at the chart I updated about 15 minutes ago you will see some interesting things:

1. The 21 "commonest" species on the island were all seen yesterday.
2. The 22nd commonest species is the Greater Yellowlegs; it hasn't arrived for the year yet; any day now.
3. The commonest species on the island, the Herring Gull, has been seen on 4,632 days since I started the database.
4. The "rarest" bird seen yesterday was the Iceland Gull, in 229th place; an Iceland Gull has been seen on 114 days since starting the database.
5. The Dark-eyed Junco moved into 81st place yesterday, edging out the American Wigeon which dropped into 82nd place.
6. Likewise the House Finch moved into 44th place, at 2177 days, just ahead of the Brown Thrasher at 2176 days.

FYI, the Herring Gull only recently moved into first place. The Canada Goose had been at the top since nearly the first version of the chart over ten years ago. Why? Well obviously because it has been reported fewer times than the gull for the past while. But why? I don't really know, but it might have something to do with the harsh winter now finally ending.

The chart uses a color coding:

1. Yellow -- the birds seen on the last update.
2. Red (hot!) -- the birds that moved up on the last update.
3. Blue (cool) -- the birds that moved down on the last update.

Take a look at the top of the chart, the first 20 species. If someone were to ask you to name the 20 commonest species on the island, how many of those would have been on your list? Would you have put Northern Harrier in the top twenty? It is in 12th place, having been seen on 3,803 days since the start of the database. I would not have guessed it was so high.

Good birding,

Tom Wetmore,
Newburyport, Mass.
Think globally, bird locally.

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