October Rodent Census


October is one of my favorite months to be at Portal. The day and night temperatures seem perfect and the days are long enough to enjoy the scenery of the desert. Because of this, it’s also one of the best times to introduce new Portal volunteers to the site. Throughout the project’s duration, many people have come to help with the rodent and plant censuses, and many of these people have not been graduate students or even biologists. This month, I was able to bring my mom, Mary Mohlman, who works at Lincoln Elementary School in Hastings, NE. Her students have actually been studying deserts this fall, so she was excited to learn about the rodents and to take lots of pictures to show the kids.

Mary helping to set traps in the late afternoon.

Mary Mohlman getting to know a desert pocket mouse which was trapped on a total rodent exclosure plot. These individuals are set free off-site after being identified and measured.

Rodents are fun!

Our trap numbers continued to increase and we had nearly 200 individuals! In addition, some of our other species made a few cameos, including four cactus mice (Peromyscus eremicus), 4 southern grasshopper mice (Onychomys torridus), 2 silky pocket mice (Perognathus flavus), and even a new Bailey’s pocket mouse (Chaetodipus bailey)! We had one strange encounter with a very, very pregnant female kangaroo rat (Dipodomys merriami) who weighed over 60 grams (usually ~ 35-45 grams)! As soon as we let her go, she started making urgent squeaking noises and ran about 5 feet away from us towards the corner of the plot where she dug a hole, climbed inside, and covered the entrance. For the next 10 minutes, as we finished the rest of the traps on the plot, we could hear her squeaking while underground. I can’t say what was happening, but it was very strange behavior.

A new Bailey's pocket mouse. So far, its still the only one we've caught on the site in the last few months.

The rain seems to have stopped for the season and the vegetation was much drier than a few weeks ago when we completed the plant census. However, there were still plenty of very large centipedes (Scolopendra spp.) and texas horned lizards to be seen (Phrynosoma cornutum).

Eragrostis cilianensis (stinkgrass) growing along side plot 12. Winter is nearing and the vegetation will soon be gone along with many of our smaller rodent species (some of which enter torpor during the colder months).

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One Response to “October Rodent Census”

  1. barney dresman Says:

    I think I caught a pocket mouse that was eating our cat litter. It is a humane trap. What should I do with the mouse?

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