I am trying to calculate the home range area using mcp.area from the 
'adehabitat' package. 

x<-c(689361,689041,689448,688871,688745,689302,690479,691284,689456,
689348,689438,689427,694824,689685,689871,689937,688933,689040,277847,
279256,279565,280644,280649,280653,280649,280232,280764)

y<-c(5356269,5356336,5356119,5356644,5356552,5357079,5356998,5360674,
5362240,5362479,5362552,5362588,5357394,5350680,5350868,5351181,5349515,
5349975,5359887,5362338,5362022,5362872,5362877,5362882,5362854,5363839,5362793)

zone<-c(14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,
15,15,15)

ID<-c(4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,
4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015,4015)

xy.data<-data.frame(ID,x,y,zone)
xy<-data.frame(x,y)

homerange<-mcp(xy, ID, percent = 95)

area.plot(homerange)  # plot the home range
points(xy, pch = 16,col='red')       # add in the relocation points

homerange.size <- mcp.area(xy, ID,percent = 95,unin = c("m"),unout = 
c("km2"), plotit = FALSE)
homerange.size

The problem that I am having is that movement occurred across two UTM 
zones, which is inflating the home range area. 
 What can I do to correct this, I am sure there is an easy work around 
that I am missing?
Any insight would be appreciated.  Thanks!
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