2009 Recovery data - distance calculations?

[Wyvern]

I just found the prelim tag recovery data information on the web last night and today cross referenced that against the records I had for the 400 monarchs I tagged last fall. I was surprised to see that 4 of my babies actually made it to Mexico ! My first time getting monarchs to Mexico. Back in 1996 I had one make it as far as Virginia.

LHR 131, LHR 151, LNT 021, LNT 059

I was wondering what program does Monarch Watch use to determine the mileage distance? Google maps wasn't exactly helpful in that regards and I haven't really found another online program that would seem to do what I want. Three of the tags were recovered in El Rosario and the fourth in Cerro Pelon..... but those are large areas to try and figure out where the best spot to pick to use for calculating distance. Lots of possible locations (different mountains, populated areas, etc. to choose from or am limited to choosing from).

Any suggestions?

[Paul Cherubini]

I don't know what distance program the Monarch Watch uses, but I do know the El Rosario and Pelon overwintering sites are quite close to one another - very roughly 50 straight line miles apart.

I'm very curious to know what location and dates you tagged the 4 recovered monarchs because a recapture ratio of 1 in 100 is quite good. Thanks.

[Wyvern]

Yes, 4 out of 400 is pretty good. I've been doing monarch tagging since the late 80's and it's the first time I ever got one to go all the way. The butterflies were hand reared from eggs/caterpillars I collected. I try to collect the eggs or cats as soon as I find them to reduce problems from parasites.

Tag/Release Location for all 4 was Clinton, MD 20735.

LHR 131
Male
9/5/08

LHR 151
Male
9/6/08

LNT 021
Female
9/12/08

LNT 059
Female
9/15/08