duck seg: segment crew: observer of the corresponding segment grid: grid cell year_2000 ~ year2010: duck counts from year 2000 to 2010 of the corresponding segment pond grid: grid cell lon: longitude of the centroid of the corresponding grid cell lat: latitude of the centroid of the corresponding grid cell year_2000 ~ year2010: pond density of the corresponding grid cell dist This is a matrix containing the distance between any pair of grid cells vcf crew: observer year_2000 ~ year2010: observer- and year-specific VCF value ch year_2000 ~ year2010: individual encounter history for each year, a value represents the grid cell in which the individual was captured, NA means not seen