Schultz burn area, rodent trapping

The last couple of weeks our crew has been studying rodent density in the Schultz Fire burn area up on Mt. Elden near Flagstaff for our project in the field ecology class we're taking. We used both rodent trapping and food plates to estimate density of rodents in different treatments across the burn area. Parts of the burn area had been seeded from helicopters with bales of straw dropped on top of the seeds in an attempt to prevent erosion of hillsides. The seed mixture used had wheat in it, which is a fast-growing annual grass. While non-native to the area, the Forest Service was put under pressure from Flagstaff residents to do something fast prevent landslides, erosion, and flood damage for those that live down-slope from the burn. So, the treatments at our site that we looked at were burned with seeding, burned without seeding, and unburned patches. Here are some more photos of the burn and these different treatments (the unburned forest is mainly ponderosa pine with some firs mixed in):
Burned without seeding:

Burned with seeding (wheat seeds and straw):

Unburned patches of ponderosa pine and mixed conifer forest:

Previous studies of small mammals in burned areas had shown that rodent populations, especially deer mice, increased in burned areas after fires. After seeing how nuked some of our sites were, we were curious if this increase would hold true here (it did not seem intuitive to us that mice would be able to find food at these scorched earth sites). We predicted that if mice were more abundant in the burned sites than the unburned, that the site that had been artificially seeded would have more mice than the burned site without seeding. So, we set 60 Sherman traps baited with oats at each of the treatments (burned with seeding, burned without seeding, and unburned) to see what the abundance of rodents was out there. The only species we caught was deer mice (Peromyscus maniculatus). As with the previous studies, we found mice way more abundant in the burned sites than the adjacent unburned patches. We also had statistically significant numbers showing that mice were using the seeded burned site more. Here are some photos of the trapping:

We emptied the traps into a large, see-through bag. Then, we had to corner the mouse into part of the bag where it couldn't escape and then pinch the skin on the back of its neck to get a hold of it. Next, we pulled the bag inside out with a grip still on the mouse. We then measured the mouse to determine species. The mice were then released, unharmed, after this to scurry off to the nearest log or rock pile. Here is a photo of Damon and Sam getting a mouse out of a trap, with Damon's dog Denali supervising to make sure the mouse didn't escape prematurely:

My "Abu Ghraib" pose with one of the mice:

Along with the mice trapping, we used food plates to determine what the food availability was like in the habitat. We based it on the concept of "quitting harvest rate", where the food in the plate will be eaten down to the same level as what is available in the habitat based on search pattern and satiation rates by the rodents. This can be used to compare food availability across different sites. We set out 7-15 food plates at the different treatment types. We used petri dishes filled with fine sand and a small amount of cracked corn. Like with the trapping, we also had statistically significant results that showed higher amounts of food in both burned sites than in the unburned site. What was surprising was that the results were similar at both burned sites, which suggests that a similar amount of food is available in the burned site that was not seeded. Possible explanations for this are that lots of native plant seeds have been washed down slope, previously buried seeds have now been exposed, or that invertebrates such as ants have been moving seeds around while recolonizing the burned sites. As far as the fact that mice densities were higher in the seeded vs. non-seeded burned sites despite similar food availability, a possible reason for this might be predation pressure differences (mice at the site without straw would have less features to hide from predators with).  Overall, a pretty cool study! Here are some pics of what the food plates looked like:

Cameron defoliation, petroglyphs

On September 24th I went back up to Cameron (off Hwy. 89 between Flagstaff and Page) in search of rare birds. I did not find any of the previous reported rarities, but lots of migrant songbirds moving through. The most bizarre sighting was of a family group of Lazuli Buntings with one begging fledgling. This seemed extremely late to be finding fledglings of any species here! I checked the Arizona Breeding Bird Atlas and fledgling Lazuli Buntings had only been reported as late as early September in southern AZ. What was even more weird was seeing the adults feeding it already in basic (non-breeding) plumage, with the only blue color remaining on their tails.

While I was down in the seep in the tamarisk thickets along the Little Colorado River below the Cameron Trading Post, I ran into another birder from the Houston area and we scoured the habitat upstream from the bridge. We found a few tamarisks that were completely brown, indicating recent activity by the tamarisk leaf beetles (Diorhabda carinulata). These beetles are native to the tamarisk's range in Eurasia and were released in the western U.S. as a means of biological control of the tamarisk, which is an invader of riparian ecosystems (mostly as a result of disrupted hydrology from damming the rivers). We did not find any of the adult beetles or larvae that day, although other birders had reported seeing a small number of them here. I think the migrating birds moving through may have been the reason we didn't see any of the beetles as I'm sure they are a tasty treat for them. The beetles are already in the Grand Canyon, so I'm sure we'll be seeing more of the beetles moving up the Little Colorado River next year. It would not surprise me if they hit Winslow and Holbrook next summer. The next day I was over in Holbrook and saw some trees that looked like they were being chewed up, but again, did not actually see any beetles (I think they might be here already though). Here are some photos of the trees being defoliated at Cameron:

Besides birding, I also saw some ancient petroglyphs/pictographs up on the low cliffs along the river. I think these might be from either the Anasazi or Sinagua indians (not sure though). The petroglyphs had been damaged by vandals, with other graffiti and some bullet holes on top of the ancient symbols. Here is a photo of petroglyphs:

One weird thing I noticed was that the river looked pretty dry when I arrived around 9:00am, but was flowing good just before I left around noon. There were some structures down on the river that might have been some sort of water regulation devices (maybe water is diverted for agriculture). Some of the dams upstream could have also released water. Here are some comparison photos: