There is considerable evidence that the Blackpoll Warbler (Dendroica striata) undertakes a non-stop, transoceanic, fall migration from New England and Atlantic Canada to South America. However, this unique migration strategy is not yet clearly understood. Based on flight range estimates, Blackpoll Warblers must require large amounts of fat for this flight. I captured Blackpoll Warblers during fall migration on Bon Portage Island, a small island off southern Nova Scotia, to determine if Blackpoll Warblers either arrive with, or remain on the island and deposit, the large fat reserves necessary for their migration. Most Blackpoll Warblers did not arrive at Bon Portage with sufficient fat reserves to complete transoceanic migration from Nova Scotia to South America. Furthermore, although young Blackpoll Warblers did show moderate rates of diurnal fat deposition while on Bon Portage, most did not remain long enough to accumulate the necessary fat reserves for transoceanic migration. I conclude then, that Bon Portage Island is not one of the final sites for Blackpoll fat deposition, and I discuss several possible explanations for these results.