It’s not quite as sweet as Prince’s When Doves Cry, but I’m working on a song titled, When Squirrels Cry. Many of the most valiant and dedicated squirrelologists ever to grace the telemetry unit are graduating. They have been awesome and will be missed by me and our grey collared friends! Best of luck everyone–once a squirrelologist, always a squirrelologist!
I’ve been much delayed in writing this post…. largely because, strap in, its sort of a wacky ride. About a year ago, in the squirrelologist lab, we had a discussion about squirrels falling out of trees. A few students and I have witnessed over time squirrels falling out of trees–about 30 or 40 feet high–bouncing on the ground, getting up, and running off, seemingly fine. One student saw saw a squirrel fall of a utility wire, land on the road, and run away, seemingly fine. We have been curious at what point these falls become lethal. There is some speculation that squirrels use their tails as cushion. However, Forsman and Otto (2006) put together an excellent paper on squirrel accidental falls, indicating that squirrels most commonly land in the “spread eagle” position. In fact, out of a massive sample of one, we too have witnessed a spread eagle landing that resulted in a fatality and blogged about it.
This curiosity led to a long planned experiment to assess the worse case scenario of accidental squirrel falls. We collected three dead squirrels that died of natural causes. We then went onto the roof of a building on campus and dropped these squirrels from the room. To be clear–WE DID NOT DROP LIVE SQUIRRELS FROM THE ROOF. THESE SQUIRRELS DIED OF NATURAL CAUSES AND WE COLLECTED THEM. We dropped one from 40 ft and two from 55 ft. Afterwards, we immediately x-rayed them in a lab here on UNE’s campus. This 15 foot elevation delta appears important. The 40 ft fall caused a single fracture at the end of the rib cage. We dissected this individual to confirm the x-ray–and indeed this was the case. The other two squirrels did not fare as well. One suffered serious rib cage damage and an oblique fracture of the right tibia and fibula. The second 55 ft also appeared to have rib fractures and a pelvic fracture on the right side involving the ilium, pubis and ischium. This small experiment suggests that squirrels can survive falls from heights ~40ft and less, but might higher become fatal. Very interesting stuff.
Forsman, E.D. and I.A. Otto. 2006. Healed fractures and other abnormalities in bones of small mammals. Northwestern Naturalist 87:143-146.
Given all the Star Wars propaganda throughout civilized society right now, it seems unfair to leave squirrels out of the intergalactic fun. Check me out (but put on your Darth Vader helmet first).
Well, one of the largest cities in Maine has decided squirrels are not welcome to join the Christmas celebration….
Here in Squirrelology-land we have been planning an interesting–albeit a bit odd–experiment on squirrel falls for sometime. We have now observed 4 squirrels in trees and 1 on a utility wire fall from up to 40 ft, land on the ground, and run off, seemingly unhurt. At some point these falls must be lethal and we want to know what that point it. Therefore, we have been planning an experiment where we drop already dead squirrels from the top of our four story building to test the impact effect of different substrates–grass, snow, ice, pavement. We plan to x-ray them after they are dropped to see what damage occurs to their skeleton (the squirrels we will use all died previously of natural causes and we collected their bodies subsequently).
This week, amazingly, we potentially got a preview of the study. One of our ear-tagged (only) squirrels was found dead outside a dorm, about 12 m from the main doorway. My read of the situation is that the squirrel was on the roof of the three story building and tried to jump to an adjacent white pine (inferred from the direction the body was pointing). The jump was a bit far and the branch tips a bit thin. The squirrel missed, and landed on the left side of its head, suffering mortal head wounds. Here are a few pictures. Let me know if you have any alternative hypotheses.