Portal lives: a long awaited update

While I’ve been busy shirking my blogging duties over the past year, many people have been busy keeping Portal up and running. After we ran out of NSF funding last summer to fund research collection at the site, we were able to keep collecting data bi-monthly for the rest of 2010 on a shoestring budget and with a lot of help from Portal volunteers past and present. Luckily for us, rodent numbers remained extremely low throughout 2010 so maintaining rodent exclosures was not problematic, even with the decrease in trapping frequency. In addition, we were able to secure some funding for the next two years and began trapping each month again in January 2011. There is not a lot of money for incidentals, so we are continuing to use a combination of pit-tags and ear tags for individual markers until they run out and are keeping our fingers crossed that the trap shed and other necessary supplies can last a few more years.

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Trapping this year has been interesting–dealing with record cold temperatures, smoke from the Horseshoe 2 forest fire in Cave Creek Canyon, and a very pesky pack rat that seems intent on living in our trap shed and destroying as many trap box shoulder straps as possible. The spring and winter were extremely dry, combined with record-low temperatures in February, and there was almost no spring germination. Consequently, this past winter, rodent numbers once again dropped extremely low (20-30 rodents in the entire site!), but enough survived the last year to reproduce this spring and our numbers this summer have been >100 rodents on site. This is still a very small number compared to more productive summers only a few years ago and we have also seen a drastic change in species diversity at the site compared to a few years ago. We are currently capturing only 4 species–Merriam’s kangaroo rat (Dipodomys merriami; common), Ords kangaroo rat (Dipodomys ordii; rare), desert pocket mouse (Chaetodipus penicillatus; very common), Bailey’s pocket mouse (Chaetodipus baileyi; very rare), and southern grasshopper mouse (Onychomys torridus; common). In 2011, it seems like we are drowning in desert pocket mice (Chaetodipus penicillatus). In fact, there are plots where kangaroo rats (Dipodomys spp.) should be “king” and instead, we are ONLY catching desert pocket mice! Its all very surprising, but perhaps that is what makes Portal so interesting.

December/January Rodents

Conditions at Portal seem to be getting worse for the rodents. Since it is cold, the smaller species are no longer showing up in trapping censuses. Furthermore, Merriam’s kangaroo rat, seems to have nearly taken over the site, comprising more that 50% of the community (at least, of the 20 rodents caught in January). We continue to catch one or two Banner-tailed kangaroo rats each month and of course, many grasshopper mice. Ord’s kangaroo rat no longer seems to be around and Bailey’s pocketmouse is also nearly absent–only one individual made an appearance in January. It will be interesting to see what shows up as things get warmer this spring! A third seed box has disappeared, this one stolen, so off we are to find another seed box that is tough enough to withstand hungry rats, but not attractive enough to be taken…

As conditions seem to be getting worse for the rodents, the loose dust provides a good way to track use of the plots!  Although we haven’t caught an individual on plot 12 for several months, it seems there is a hungry kangaroo rat trying to get in! By January, every animal traversing was leaving tracks, making it interesting to determine who/what was around.

The dust seems to be winning the battle in this photo taken on plot 12 in December. It was even worse in January, with every step leaving tracks in the dust inches deep.

Banner-tailed kangaroo rat mound on plot 23. We catch this individual nearly every month.

Ryan O’Donnell, a grad student at USU, made a 3rd appearance at Portal in December to help with trapping and to practice his wildlife photography skills.

Fantastic sunsets in January did not disappoint myself or my helper for the month,  Ken Locey, a grad student in Ethan White’s lab at USU.

January saw signs of spring germination with many small plants breaking through the crust.