Summer is in full swing at the HJ Andrews Experimental Forest. Two weeks ago, we had our annual Safety Day presentations led by Mark Schulze and Brenda Hamlow and last week, we had our largest outreach event, HJA Day! For HJA Day this year, I led a morning station with Steve Ackers, the Spotted Owl Crew Leader for the HJA, and introduced participants to some of the long term data that has been collected on the northern spotted owl (Strix occidentalis caurina) and some of the new work that we have been doing on mammalian carnivores. Unlike other years, it has been unusually chilly and rainy this summer, so thankfully, Steve brought his EZ-up canopy so our station would stay dry.
For show and tell, I brought my collection of mammal skulls and Steve brought in some specimens from the spotted owl diet reference collection. The specimens from the reference collection are pretty cool because they are used to identify animal bones found in owl pellets. Whole carcasses of potential prey items (e.g., deer mice, voles, flying squirrels) are carefully skinned and prepared so that the dermestid beetles can eat the flesh and clean the skeletons. Once the skeletons no longer have any flesh, the skeletons are carefully placed in Nalgene containers, labeled
(with species, sex, and location of collection), and stored so they can be used as a reference for miscellaneous bones. If the location of each bone is preserved well, this method of cleaning the bones can also be used to re-articulate the whole skeleton of an animal. These reference collections are incredibly valuable because they let us identify what the animals in the HJA are eating and how much they are eating.
In addition to the specimens, I presented some photos of carnivores that we've captured on trail cameras around the HJA and some diet trees of what those carnivores have been eating. Unlike the owl pellets, we use DNA metabarcoding to identify prey items in carnivore scats. Last year, we contracted the Conservation Canines from the University of Washington to collect carnivore scat to bolster our opportunistic scat collection samples. This year, we have analyzed about half of those samples using DNA metabarcoding to see what the carnivores were eating. DNA metabarcoding is a technique where we extract DNA from scat samples. Once we extract the DNA, we amplify a region of the mitochondrial DNA that is unique to each vertebrate species. This means that the sequence of nucleotides (i.e., A, T, G, C) in this region is different and unique to each species. In other words, the sequence for a deer mouse is different than one for the Townsend's chipmunk. Therefore, when we get a sequence from a particular scat, we can compare it to a database that has these sequences for each possible prey item, and identify what animal was consumed. Using these results, I constructed some preliminary diet trees so everyone could see how different a diet of a bobcat was from a mountain lion. In the mountain lion diet tree, only a portion of the diet tree is colored, showing that the mountain lion has a pretty specialized diet. On the other hand, the bobcat diet tree is very colorful, showing that the bobcat has a very generalized diet and can eat many different prey items.
In other news, our crew is finally complete! Kristen Van Neste has returned back to the HJA to work on the skunk crew (previously the small mammal crew), Sriram Narasimhan joins us from Stanford to conduct his REU project on berry consumption by vertebrates in the HJA, and Allison Hay joins us from Texas A&M to conduct her internship and gain experience from all the crews at the HJA. Unfortunately (or fortunately for Sriram and Allison), we have started trapping skunks again because the collars that we worked so hard to replace in the spring have almost all failed! The new antennae that we switched to this spring have been unreliable, and we have not been able to track our skunks unless they are VERY close to the road (~10 m). On the 4th of July, we captured an Independence Day skunk (a new skunk) that we worked up and collared. Sriram and Allison's first western spotted skunk (and nobody got sprayed)! Hopefully, this bodes well and we can get a decent sample size for the summer.
To finish off the week, we grilled a delicious Independence Day meal and went to go watch some local fireworks at the Tokatee Golf Course.
