Tetrapod Zoology

I picked up a lot of dead stuff in Morocco. One of the neatest things I brought back was this very large owl pellet (now broken into bits), discovered by Dave Martill at the same place where we were awoken at night by big, hooting owls assumed to have been Desert eagle owls Bubo ascalaphus [back-story here]…

As you can see (close-up below), it’s stuffed full of rodent bones, at least some of which are (I think) from jerboa. So far I’ve only had a cursory look, but bones belonging to several individuals of more than one species are present. If and when I get round to extracting and identifying the bones, I’ll let you know. Owl pellets are excellent if you like collecting tiny mammal bones, but the size of this specimen puts my Short-eared owl Asio flammeus and Tawny owl Strix aluco pellet collection to shame.

Comments

#1 Jorge Velez-Juarbe
February 21, 2009

Nice, that is indeed large!! Owl pellets are always so much fun!! They are also the source of a lot of our knowledge of the Pleistocene fauna of the Caribbean and probably of many other places as well.
#2 Adrian Thysse, FCD
February 21, 2009

Last night my daughter and I attended a meeting of the Edmonton Nature club. The guest speaker was Roy Schmelzeisen, a biologist with the Alberta Conservation Association. He discussed how the analysis of pellets retrieved from Great Horned Owl roosts and nests help wildlife managers to determine the population status of mice, voles and other small mammals. Apparently this is providing better results than snap trapping or live trapping.
#3 Rosel
February 21, 2009

I saw a Jerboa last night.

and I have a a bag full of desert eagle owl pellets.

How are you going to ID the bones? Cause if there is any Public domain info on the bones of jerboa, gebils and the like I’d love to use it when I dissect my pellets.
#4 Alan
February 21, 2009

Since many birds , not just owls, produce pellets, is there any evidence that dinosaurs did to? Could this be a source of deposits of small mammal bones in Mesozoic rocks?
#5 Darren Naish
February 21, 2009

Hi Alan. Go here!
#6 Metalraptor
February 21, 2009

Ah yes biology, the only science where you get to poke around with poop, vomit, urine, and roadkill for a living and be able to say with an absoltely straight face that you are making an honest living.
#7 Metalraptor
February 21, 2009

“Nice, that is indeed large!! Owl pellets are always so much fun!! They are also the source of a lot of our knowledge of the Pleistocene fauna of the Caribbean and probably of many other places as well.”

You gotta love the giant killer owls of the ancient Caribbean.
#8 Tommy Tyrberg
February 21, 2009

Owl pellets are indeed more effective than trapping for surveying small mammals. Tyto alba pellets seem to be best of all. Bubo pellets will occasionally also sample rather larger mammals and birds. Bubo bubo is a very efficient hunter and can take prey as large as Osprey.
#9 Mo Hassan
February 21, 2009

Sorry to be a touch pedantic (this quality often helps in taxonomy), but you said the short-eared owl is Asio otus, when it is Asio flammeus, with A. otus being the long-eared owl, but of course you already know that.
#10 Darren Naish
February 21, 2009

Oops, thanks Mo.
#11 Katkinkate
February 22, 2009

Now that’s a jigsaw puzzle!
#12 davidd
February 22, 2009

Off topic, but: final photo for “Ankylosaur Week 2009″ at Flickr:
http://www.flickr.com/photos/puuikibeach/3299796246/in/photostream/

Then, of course, there’s the alternate version:
http://www.flickr.com/photos/puuikibeach/3299796648/in/set-72157614184938050/
#13 Graham King
February 22, 2009

Makes me wonder if anything selectively eats owl pellets (ok, not just those!) for the concentrated calcium therein?

Are the pelleted bones calcium-depleted relative to fresh-killed (uneaten) small-mammal bones?

Does owl pellet composition vary during nesting (more calcium needed, from those bones, for making egg-shells) or are the bones regurgitated before much useful calcium/etc absorption takes place?

Or do birds (and did dinosaurs) simply draw on their own skeletal reserves and so not need ‘extra’ calcium intake in breeding season?

I have wondered if bony excrescences of some dinosaurs (frills, armour, bone-domes of Pachycephalosaurs etc) might usefully have served (amongst other uses) as storage depots for calcium/other minerals: as reserves of what might otherwise be limiting factors, thus allowing species so endowed to lay larger or oftener-repeated clutches of eggs, and/or to regurgitate calcium-rich material, to give their young a selective advantage ie rapid growth.

If so then these features could be structures both signalling and embodying fitness to breed…
#14 Nathan Myers
February 23, 2009

Metalraptor: You gotta love the giant killer owls of the ancient Caribbean. Seven with one blow, right? How did ancient Caribbeans (except the giant ones, of course) ever got along without those owls?
#15 Stephen Crute
September 18, 2009

Hi, I came across your piece about Desert Eagle owls and pellets.

I have been collecting and dissecting pellets found here in Saudi Arabia. I have recently taken one apart and have an impressive collection of bones. Did anyone ever find a source for the identfication of gerbil and jerboa bones?

Litte is known about small mammal distributions in Saudi so being able to ID the bones from pellets will be a step in the right direction.

Thanks

Stephen
#16 Darren Naish
September 18, 2009

Hi Stephen – I have not been able to find any key for the north African rodent bones I needed to identify, so cannot help. If anyone reading this has further info please do post it.