Reliquia santamartais an unusual Pierine butterfly endemic to the Sierra Nevada de Santa Marta of northeastern Colombia, where it flies above 3500 m. Its biology is of particular interest because of the possibility that it might be a relict derived from the otherwise HolarcticPieris callidicegroup, which it strongly resembles phenotypically. Its behavior was studied afield for comparison with Nearctic members of that group. MaleR. santamartaare vigorous hilltoppers, assembling to topographic prominences, while females are frequently encountered at lower elevations. Flight patterns, thermoregulatory postures, and interactions between and within the sexes are all virtually identical to high‐montane and alpine NearcticPieris.The natural host plant was not determined. The role of seasonality in the biology ofR. santamartais discussed. Behavior data alone are inadequate to determine whetherR. santamartais closely related to or strongly convergent with the Nearctic taxa.