Portal Squee: Nesting Cactus Mice

This post is way overdue, but the photos are so cute that I couldn’t help myself. Back in March 2012, when Glenda Yenni, Xiao Xiao and I travelled to Portal to count the winter plants, we discovered cactus mice (Peromyscus eremicus) nesting in a box that we were using to hold firewood. When we took the wood out of the box, there was a flurry of activity and a big fluffy nest inside!

A scared cactus mouse runs around the box.

What was even more interesting was that the nest had a two (eartagged!) adults  pair with 2 different ages of offspring! There were 3-4 subadult mice along with 2-4 teeny tiny juveniles (it was hard to count in the dark with all the running around). The juveniles were small enough (although they did have hair) that they remained attached to the nesting female when she ran out of the nest.

I mentioned this to Karen Mabry, who sometimes helps out at Portal, and she suggested that although not much seems to be known about Peromyscus eremicus, they may be “more monagamous” than some other species mice. Some other Peromyscus species are known to be socially and genetically monogamous, and have sometimes been confirmed as nesting with sisters (rather than a male-female pair), which could potentially explain why there were 2 different ages of juveniles in the nest box.

Female cactus mouse peers out of nest.

(Photo credits: Glenda Yenni)

January trapping update

One of the best things about working in the desert (especially when you’re doing long-term ecology!) is that things are always changing. After the recent drought, we saw a decline in biodiversity at the site that rivaled anything seen throughout the course of the 35 years of study, including the dominance of the rodent community by a very small-sized species (Desert pocket mouse, Chaetodipus penicillatus) which surprised us all. After some decent rains in 2011, diversity is slowly returning to the rodent community as we have been seeing more of the generalist species return. These species seem to be more transient at the site, popping up when conditions are right for them. I was still a bit surprised, however, to catch several plain’s harvest mice (Reithrodontomys montanus) in January! This is a species that I hadn’t seen in a few years, so it took me a moment to determine what I was seeing.

Another of the generalist species that has been popping up this winter is the cactus mouse (Peromyscus eremicus). We even found a nesting pair in our trap shed this past month! They were pretty cute, but since our trap shed has recently been inundated with other living things–pack rats and most recently, at least one rattlesnake and a badger living underneath the shed, I chased them out. I really don’t want the shed to seem like a larder for our resident rattlesnake. Pictured below, is my volunteer of the month, Loren Sackett, from University of Colorado at Boulder.

Loren studies prairie dog populations, genetic divergence and pathogens in the southwest. You can read about her adventures at the prairie dog blog.

Meanwhile, the rain seems to have slowed from earlier in the winter but the plants are still growing! We’re headed down to the site again in March to have another rodent-trapping-plant-field-extravaganza.

Above, Rumex, Erodium, and Guterrezia all green up. The vegetation at the site seems hard to categorize and we’ve had trouble finding just one or two field guides to use when we do the plant surveys. Luckily, over 25 years of work at the site has led to the compilation of an amazing  mini-herbarium of pressed plants and identifying characteristics that we can bring down with us when we do our plant surveys. I’m currently working to update this herbarium and have found several websites that are also really helpful for plant identification in the area, such as this NMSU website, this Arizona wildflowers website, and this New Mexico flora website. I’d love to hear any other suggestions of websites or books that are helpful for plants in the Portal area–please share!

Seed pods from Devil’s claw (Proboscidea parviflora) on the fence of a rodent exclosure, Chiricahua mountains in the background.

It was pretty small, but I’ve never seen a tarantula in January before!

Loren sets traps at sunset.