why not found west of the cascades ?

asked by mitch martin over 8 years ago
  • 2 Answers
Dave Irons
1. by Dave Irons on March 11, 2014 at 12:10 am
Very interesting question, for which I don't have a good answer. I suspect that part of it is a niche thing. It occurs to me that they tend to be in places where American Crows are not resident. It is little known to most folks that American Crows vacate most of eastern Oregon during the winter months and in some places east of the Cascades they are absent even during the warmer months. Perhaps magpies are the default corvids in places where crows are absent or non-resident, but cannot compete with crows where they are resident. I will do some research when I have the time and see if I can come up with a better and less speculative answer.
Dave Irons
2. by Dave Irons on March 11, 2014 at 12:25 am
Just did a quick online search and found some references that seem to confirm my earlier speculation. I found one reference to work in Sweden that talked about competition between European Black-billed Magpies and Carrion Crows (very similar to Am. Crow). It refers to "interference competition" between these species, which share similar diets and foraging habits. The paper notes that crows have been known to kill adult magpies and that they regularly raid magpie nests, predate the young and eggs and/or cause magpies to abandon nests, that in some cases are then taken over by crows.
mitch martin
reply by mitch martin on March 11, 2014 at 08:28 am

thanks, Dave. i love those magpies and always look forward to seeing them when i'm headed east. it's bothered me for years that the crows and ravens make it west of hood but i've never seen a magpie this side (i'm in portland). Thanks for responding