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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4 Comments

  1. Austin said,

    August 29, 2009 at 8:40 pm

    carl.

    Our town periodically sprays for mosquitos over the summer, I often wonder how this affects the various non target species in the area? I imagine it could potentially impact less mobile species like the true katydid, individuals on isolated trees could eventually vanish unless they have some mechanism for recolonising those isolated trees/small patches.

    Post spraying I have seen field crickets on their backs flailing their legs and cicades spinning on their backs in an attempt to fly also once a large conehead visibly shaking/vibrating as it was walking (it wasnt singing) I will suggest anecdotally that the spray could have affected those insects. A conversation I had with a local control representative assured me that the spray wouldnt harm ‘large, hard shelled insects’.

    perhaps then only the ‘small, soft shelled insects’!

    I do find it alarming that spraying inevitably leaves a toll especially when individuals can potentially protect themselves 100% from mosquito bites.

    • natureinquiries said,

      August 31, 2009 at 5:56 am

      That’s a good point, Austin. My town gave up mosquito spraying years before I started my block counts, so I don’t have a means of assessing that impact.

  2. Austin said,

    August 31, 2009 at 7:45 am

    carl.

    thats lucky. I have to say that i am dismayed when I encourage wildlife into my garden through native planting and then find the whole lot subject to pesticide by a process that i consider to be utterly indefensible, there is a time and place for adulticiding mosquitoes and as far as i know the conditions that present themselves in our town simply are simply nowhere near those criteria.

  3. September 26, 2012 at 6:04 am

    […] I have a solution that works for me, and perhaps it could be made part of a protocol. When I do my block counts at night, I count only those individual singers that are close enough for me to distinguish clearly […]


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