Posts Tagged ‘rain’

Holiday season with the Portal rats

December 21, 2011

Trapping at Portal is usually done on the weekend closest to the new moon. This is done for a number of reasons: 1) trapping at the same time each month lends consistency to our methods, and 2) evidence suggests that rodent may be most active outside of the nest under the cover of the darkest time of the month (but then again, maybe not). This year, the new moon fell on the day after Thanksgiving and again on Christmas Eve. As much as I enjoy handling rodents, I pushed back the monthly Portal trips to the first (Dec 2-4) and third quarter (Dec 16-18) of the lunar calendar.

When the temperatures drop, many of our smaller species disappear for the winter as they enter torpor to save energy and remain warm in their burrows. Although larger species, such as the kangaroo rats and grasshopper mice stay active year round, they are still susceptible to cold desert nights, which commonly dip as low as 20 F in the winter! Getting wet, even a little bit, when it is so cold can kill even these larger individuals. So when I arrived in Arizona on Dec. 2nd to see rain clouds in the sky,  I knew that trapping that weekend was just not going to happen.

rainy Portal road

Given the total lack of rain last winter in southeastern Arizona, and the nasty fire season they experienced this past summer, the rain is much needed. So although we weren’t able to set out traps, Tim Bean, visiting from UC Berkeley (where he studies the endangered giant kangaroo rat!), helped me with some site maintenance activities.

Erosion around the gates in our fences has continued as the rain falls, so we took advantage of the damp soil to rebuild little ‘ramps’ for the rodents to use to ensure that immigration and emigration from fenced plots can still happen.

While walking around all the plots, we also filled in holes that seemed to go under our fences. Here, a badger has successfully created a superhighway into one of our total rodent exclosure plots, right under the bottom of the buried wire mesh.

Here, Tim valiantly fills in the hole. Not a very good substitute for getting to see cute kangaroo rats, but it had to make do.

Germination has already begun, and if the rain keeps up, there should be a lot of vegetation this spring!

For the second December trip, I brought along ASU researcher with the CAP LTER, Julie Ripplinger, and we were lucky enough to be able to set traps one night, despite rain clouds lurking in the sky.

Julie is pictured here holding a cactus mouse (Peromyscus eremicus), which seem to be relatively abundant right now! We caught nearly all of them in pairs, one trap right next to the other and nearly all were in breeding condition. Cactus mice may breed year-round if conditions are right. They are also quite pretty mice with their orange-y sides, large ears, and very soft fur.

In addition, we continue to catch a solitary Bailey’s pocket mouse (Chaetodipus bailey); the species that was once our most dominant seems to be hanging around nearby…

Rain clouds hung around all day on Saturday (Dec 17) so we erred on the side of safety and didn’t set traps on our final night. Instead we completed more plot maintenance, this time focusing on stabilizing our trap shed. The shed is one of those snap-together plastic outdoor sheds which works fine for our purposes, but from time to time begins to fall apart and needs snapped back together. During the past two weeks, something dug a large hole underneath so it was completely destabilized. I wanted to take it completely off its cobbled-together rock base and rebuild it, but Julie stopped me when she saw the tail of a mojave rattlesnake poking from underneath the shed near my hand. Again deciding to err on the side of safety (snakes often overwinter in large groups, called a hibernaculum), I satisfied myself with carefully filling in the part of the hole I could see and stabilizing the roof of the shed.


Monsoon showers bring summer flowers

October 31, 2011

Last month, September 30-October 5, a group of fellow Portal enthusiasts (Zachary Brym, Katherine Thibault, and Christa Weise) got together at the site to take on not only the rodent survey, but also the summer annual and perennial plant survey. Each experimental plot (50 m X 50 m) also has 16 (0.5 m X 0.5 m) permanent plant sampling quadrats within it so that we can understand what changes might occur in the plant community from year-to-year or based on differences in what rodents might be munching or moving around their seeds. We weren’t sure that we could actually finish the survey between our schedule flights to Arizona, but found that a determined group of (mostly) mammalogists could actually do pretty well at identifying desert plants!

There doesn’t seem to be a great field guide for the plant occurring at the site (barely in Arizona, almost in New Mexico, and a desert transition zone…) but we compiled a small ‘library’ to take out with us including a mini-herbarium of plants pressed over the years, the Flora of New Mexico book, Flora of Arizona Book (Epple), and the Peterson Field Guide to Southwestern and Texas Wildflowers, and a Grasses of Arizona Book. We’d love to hear any suggestions for other guide books for the area, especially for grasses or non-flowering ID characters.

The weather was great and by working all day everyday, we were able to sample all our rodents (still a desert pocket mouse takeover) and get to all the plant quadrates with very few unidentifiable individuals! The area near the Chiricahua mountains seems to have gotten more monsoon rain that many other areas of southeastern Arizona, so there were quite a few plants to count relative to some other years, and I would guess (haven’t finished entering data yet!) that there were about 15 species of annual plants per plot. This is actually relatively high diversity for this site, since many years have less than 5 species present! Most common was the Summer Poppy (Kallstroemia grandiflora), Woolly Tidestromia (Tidestromia lanuginosa), two species of spiderling (Boerhavia intermedia and torreyana) and panicum grass (Panicum arizonicum and hirticaule). We tried to photo document everything identified (and unidentified!) and hope to update our mini-herbarium soon since many of the samples are becoming worse for the wear.

It was a lot of work and a cobbled together fast trip, but we sampled everything and had a lot of fun!

This is a photo of plot 16 showing the vegetation this year. It may look sparse, but its a lot more vegetation than in the last few seasons!

Pit tagging a small desert pocket mouse, Chaetodipus penicllatus.

Kate gets reacquainted with the rodents.

Working on identifying plants in a quadrat, with Christa Weise.

Using the herbarium cards to identify a more rare species this year, Euphorbia micromera.

This is an unidentified carpetweed, Kallstroemia spp. It was really common this year...Any ideas?

Some of the grasses are tricky! We brought back samples of this one, but couldn't decide if it was Eragrostis arid or intermedia. We left the site leaning more towards intermedia.

Zack Brym, Kate Thibault, and Christa Weise work hard on an especially grassy sampling site.

We were lucky to get showers each afternoon to cool things down.

February trip

March 8, 2010

Last month, the site received a lot of rain (approx 3 1/2 inches), which appears to be changing conditions quickly. Rodent numbers are increasing again (up to 31!) and many are already showing signs up becoming reproductive.  Mostly, we caught Merriam’s Kangaroo rat and Grasshopper mice. The dust has settled and the winter annual community appears to be doing well–some of the plots look quite green! We had lots of help this time with NMSU Las Cruces volunteers Dr. Karen Mabry, her field technician Andrew Henterly, and grad student Jane Smith, from another lab.

banner tailed hflbanner-tailed kangaroo rat on plot 23.

cave creek canyon and plotsA view of Cave Creek Canyon and the plots in the morning.

Fall Rodent update

January 20, 2010

This fall the dramatic decline in the number of rodents caught on the Portal plots. By November, we dropped from 94 individuals in August to only 31. We remain busy keeping things running, however, especially since some very hungry rodents ate through 2 seed boxes in less than 2 months! Kate Thibault and Travis Perry, along with their field class from Furman University, joined me at the site in September and October to help with data collection. Michelle Lute, a grad student studying macaques at University of Notre  Dame, joined me in November to learn something about small mammals and the desert.

"bring more blue boxes amigo"

The resident ramada packrat chewed our seed box in no time.

western box turtle

western box turtle

The field class found this box turtle crossing the road near the site in September.


The saga of the weather station continues as we attempted to fix it this fall. After replacing it with a spare on for a month, we were able to get the data, but are still working out the bugs post re-installment.


It rained a bit almost every trip down this fall. Here are some pictures of a strange misty rain in Cave Creek Canyon during trap setting in November.


Michelle gets to know a Dipodomys spectabilis.