Posted by Sally King on March 20, 2011 at 10:29 PM
At the Bosque de Apache on Thursday we came across a cormorant sitting on a perch next to the boardwalk. The cormorant first did some wing spreading plus shaking and then spent more than 5 minutes with its mouth open, its throat puffed out and fluttering. Does anyone know what this behavior would be about? Do cormorants spit out non-digestable material this way like an owl?
Posted by Luke Ormand on March 20, 2011 at 10:59 PM
Yes they expel pellets - which is helpful when you eat so much fish whole! This comes from a scientific paper I found googling about DC Cormorants and how pellets help biologists figure out what the birds are eating.
" Adult cormorants usually eject one pellet per day in the morning before leaving colonies or roost to feed. All digestible materials appear to be expelled at that time and the expellation is independent of the number of meals or species of fish"
Posted by Jim DeWitt on March 20, 2011 at 11:04 PM
Sally -
Cormorants regurgitate pellets. BNA says,
Pellets of fishbones, crustacean exoskeletons, and/or small pebbles (function unknown), or rarely snails (especially Littorina), are common at nesting and roosting sites in both marine and freshwater locations; residual pebbles may be abundant. Pellets produced by adults and older chicks typically weigh 5–60 g (dry). Fresh pellets are enveloped in soft mucus, which hardens as pellets dry and eventually disintegrates.
Usually there's not much fuss. This bird may have some kind of a problem.
Posted by Paul Kennedy on March 21, 2011 at 4:49 AM
Panting and gular fluttering in birds is to do with preventing overheating - unless I have misinterpreted your description of it's behaviour! It's feet look a mess by the way, and it looks like it may lose all it's webbing.
I wonder if he suffered frostbite damage from the extreme cold snap that hit the area in early February. We had some pelicans in our hospital in Florida with web damage from cold.
Thank you so much for the responses. I wasn't sure about the regurgitation of pellets in cormorants. I did notice the feet. I wonder if this individual is just stressed from bad health and was overheated on a relatively mild day. Doesn't speak well for its chances of a long life. We did have record cold down here in February and it took a toll on many plants and animals.
Discussion
5 replies" Adult cormorants usually eject one pellet per day in the morning before leaving colonies or roost to feed. All digestible materials appear to be expelled at that time and the expellation is independent of the number of meals or species of fish"
Cormorants regurgitate pellets. BNA says,
Usually there's not much fuss. This bird may have some kind of a problem.