Thursday, October 29, 2009

Rankin Migration - 29 Oct. 2009

Blue traveled another 800 miles between Oct 21 and Oct 28 for a total of 5100 miles on migration. This week took him over the Venezuelan Andes and south into Columbia near Gaviotas. The GPS transmitters that these birds are wearing also record ambient temperature. When combined with lack of movement and decreasing battery power, low temperatures can be indicative of mortality. Typically temperatures are between 28 and 32 degrees C, so I was a bit alarmed when I saw temperature values below 10 degrees C. After checking altitude in Google Earth, I realized that Blue was in the mountains 2400m above sea level after having left the lowlands west of Lake Maracaibo (400m ASL) less than 8 hours earlier. The data show that he roosted overnight on a river bank…I think the sudden and temporary drop in temperature means he may have taken a bath first thing in the a.m.!.

The following GE terrain image will give you some perspective of his movements in the mountains.

and the following two photos are Panoramio images imbedded in GE and were very close to where he roosted.
Red added another 600 miles to the previous tally of 3900 miles for a total of 4500 miles to date. His most recent data point had him 39 miles NW of San Jose, Costa Rica.

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