Block Counts

by Carl Strang

Sometimes I collect data without a particular question in mind, on the possibility that I may learn something that guides a future inquiry. My block counts of singing insects are an example.

Block count 1b

My mailbox is a block away from my home. When the singing insect season arrives in the latter half of July, I begin going around the block the long way to retrieve my mail. The above photo shows the first side of the block as I head north. Next, I turn the corner and head west.

Block count 2b

I vary the starting time, record that along with date and temperature, and count the number of individuals of each singing insect species I hear along the way. Here is the view as I turn south.

Block count 3b

This neighborhood may not look like much, but I have heard a total of 14 species here from 2007 to date, including field crickets, bush crickets, trigs, ground crickets, tree crickets, true katydids, false katydids and cicadas. These data allow me to get some understanding of how species vary in numbers between years, and how their singing changes over the season and with time of day. Once I have picked up the mail, here is the final block as I turn to home.

Block count 4b

One pattern I would have missed without the discipline of the block count is a pause in singing among the cicadas in late afternoon, followed by a big push as light fades toward dusk. I have documented the arrival of a new species, the jumping bush cricket, in the neighborhood. Striped ground crickets and greater anglewing katydids were the most abundant singers in 2007, but while the stripeds also were the top species in 2008 there was a big drop in numbers of singing anglewings. It’s a little early to say much about 2009, but so far there seem to be more Carolina ground crickets than in the previous two years.

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