Differences between temperatures of air and the surface of pipes at nesting and non-nesting snow pole by Tree Sparrows.

Differences between temperatures of air and the surface of snow pole pipes  at each survey date and each snow pole. The X-axis is the same as in Fig. 2, in the order from the 1st to 12th measurement point from the pipe entrance. Sparrows were nesting in PoleID 1, but there was no clear difference from the other poles.