Cattle Egrets on the Move

I have been seeing lots of Cattle Egrets around Davis the past couple of weeks.  Before a couple of weeks ago, I did not see any moving through the skies over Davis, but now I am seeing them frequently.  They have been in groups that range in size from five or six up to flocks of 25!  Very beautiful birds.  From what I know of their annual schedule, some should be starting to molt (if they started breeding early in the season and have already fledged their young) or still have young birds to feed (if they started breeding later in the season).  So, I am guessing that the groups I am seeing are family groups of adult and juvenile birds or perhaps a few family groups that have merged together.  Cattle Egrets are very successful dispersers.  Originally native to Africa and southern Europe, they are now found on every continent except Antarctica and also on many remote islands, and they have done so without human intervention crossing from Southeast Asia to Australia in the 1930s and crossing the Atlantic Ocean from the west African coast and making landfall in northeastern South America in the late 1800s.  The first recorded breeding pair was in Florida in 1953.  In South Africa, where their population is generally sedentary, individuals or small groups of juvenile birds have been frequently observed to go long distances when leaving their natal area in search of new breeding areas.  This behavior is common to many of the Egrets and Herons, but it is especially well developed in the Cattle Egret and it seems to be one of the major factors that have allowed them to cover the globe.  In fact, the dispersal of individuals across large bodies of water is probably still occurring because these birds are regularly seen be passing ships far out at sea.  With so many examples of species being introduced by humans into new areas, I think it is really cool and interesting to see an example of dispersal happening naturally, as it has been happening for millions of years.

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