Boundaries – blog 17

Hi! I’ve stopped calling these blogs ‘Day something’ because they are already getting out of synch!

I’ve already told you twice, so this is time number three, that I crossed the Mississippi River two days ago.  That marked a sort of boundary between east and west. Yesterday I passed another boundary, and another today.

Today’s was easy – the Monarch Crest marks the Great Divide. If I spat on one side of the pass my spit would go to the Atlantic but on the other side it would be Pacific bound.  By the way, I didn’t do anything as coarse as spitting.

Yesterday’s boundary was an entirely imaginary one – but real enough! Let me explain. The 100th meridian is a line 100degrees west of the imaginary north/south line through Greenwich. It  goes through Dodge City I noticed as I went around the said city (choosing not, tempting though it was, to take Wyatt Earp Boulevard).

The 100th marks the boundary between eastern and western birds in the USA.  Here’s an example – the eastern kingbird is a nice bird that sits on wires by the side of the road.  It is easy to see and easy to identify; it has a Union blue back and a tail with a white tip.  I like them.  I’ve probably seen them almost every day since I arrived in the US of A.

The western kingbird is almost as nice. It sits on wires by the side of the road too but it wears Confederate grey.  It has white sides to its tail.  I like them.

The first western kingbird I saw was just before Dodge City and a little before the 100th.  I haven’t see an eastern kingbird since Dodge City.  There are many western kingbirds in front of me and all my eastern kingbirds are behind me (until I recross the 100th later in the trip – I’ll let you know).

There are lots of other species with similar ranges.  It’s as though there was a race, and a bunch of species set off from the west and another from the east and they met at the 100th and called a truce.  And, indeed, it was a bit like that!

When America was glaciated there were warm places left as refuges, by chance, on the southeast and southwest of the country.  Species ended up in them and some evolved differently in their two refuges.  when the ice melts species spread back and meet in the middle.  Amazing – eh?

It is a bit more complicated than that – but not much.  So for much of yesterday and today I have seen western kingbirds, western tanager, mountain bluebird, spotted towhee and white-throated swift.  Different species.

In Strong City a couple of nights ago, as I came out of the Longhorn Saloon, there were chimney swifts flying above me. No more!

This is a short blog as I am going out to grab something to eat and then spending the evening looking for wildlife in a National Park. Wish me luck!

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3 Replies to “Boundaries – blog 17”

  1. According to Conor Jameson's new book on Goshawk there are 2 and may be 3 sub species of Goshawk in America. The aggressive birds found in Maine have been shot out of UK Goshawks and only the quirt ones survive the keeper's gun but not their larson trap. Evolution of a man made environment where learning fast can save lives just like the town breeding Goshawks in Berlin and the modern day breeding Peregrines in towns and cities while country Peregrines are shot to pieces on the Red Grouse moors!

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  2. Wonderful blogs Mark evoking a rich description of 'roads less traveled'. Wake up each morning and look out for the next chapter! (After I've made my wife a cup of tea first if course! priorities priorities!).

    Richard

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  3. Loving the description of the different birds in US of A sometimes I wonder if you're winding us up their names are so peculiar but I guess I need to invest in a good American bird book, pity Audubon's is so expensive !
    Just thinking of using the topic when setting a quiz for our local Liverpool rspb group when we restart our evening meetings in the autumn.

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