Re: Hot spots for the week of Sept 15 -21

A worthy endeavor! Bar charts allow birders to determine when species are present in countries, states, counties, or hotspots. Have a look at the well-visited San Diego River mudflats & Robb Field hotspot. Note that each month is split into four weekly columns (with “week” four including the 22nd–31st of the month) and there is a row for each species. The thicker/taller the column, the more likely that species is to be present that week, a single dash means that species occurs on less than 0.3% of complete checklists for that week, the thickest/tallest cells mean a species is on 60–100% of checklists in a week. These patterns are more apparent in the histograms accessed by clicking the link to the right of the species name. Compare a year-round, “can’t miss” species like Great Blue Heron, which should have the maximum height in each weekly column to a seasonal species like American Wigeon, which is basically absent in summer, grows increasingly common in fall beginning in September, maxing out by late November-early March before declining into late spring and then disappearing again. Take a look at the combined histogram for American Wigeon and Great Blue Heron – pretty cool! There is data for every week of the year for this hotspot, and so the bar chart is filled-in or ‘completed.’ A visitor could look at this chart and know what to expect with some degree of certainty. Note the very thin bars for Ring-necked Duck – is this a place to go for this species? Probably not! A species appearing in only a single week or two (see Hudsonian Godwit or Bar-tailed Godwit), should not be expected either! Of course, more data is always useful. 

Now look at one of the hotspots John is seeking help with ‘completing,’ Silverwood Wildlife Sanctuary. With just 464 checklists, more work is needed. Note the gray pixelated columns for two weeks in August and three weeks in September. There are no data for these weeks. Note, too, the very coarse scale in which the data are presented for migrant species like Black-headed Grosbeak and the histogram is very strange (compared to the neat American Wigeon example above) – it shouldn’t be this erratic, but there just aren’t enough data here to make the fine scale pattern more apparent. 

What John is asking for is help visiting these less-visited locations, or even well-visited locations that are simply missing one week (or more) of data. Think of it as temporal pioneering! Let’s get rid of those gray, pixelated columns!

Kudos to John and Michelle for already ‘completing’ ~200 hotspots in their 5MRs.

Note that data plotted at personal locations do not appear in these hotspot tools. They do appear in county and state level tools, but these are far less useful on a day-to-day basis.

Justyn Stahl
North Park