Date: 1/8/18 2:18 pm
From: Charles Coston <cjcoston...> [south-bay-birds] <south-bay-birds-noreply...>
Subject: [SBB] Re: Seeking info on local Purple Martins
Hello AllMike Azavedo's comment on the Starling invasion is off in time.  I checked the San Jose Christmas Count data from 1970 to 1980.  In '70 it was ~4000 and going up.  By '74 it was over 20,000, which held only about 3 years.  By '80 it was down to ~8000, and slowly fell off thereafter.  A typical invasion pulse, where natives are disrupted by the invader, which has few enemies and parasites.  Over time the natives learn to cope, or get crushed, and the invader's numbers fall to a stable lower level.  Martins don't show up in the Christmas Count data, so data on their earlier numbers will have to come from other sources.  
Charles Coston
 
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