Manipulation of photoperiod induces fat storage, but not fat mobilization in the migratory songbird, Dumetella carolinensis (Gray Catbird).

The annual cycle of migratory birds requires significant phenotypic remodeling. We sought to induce the migratory phenotype in Gray Catbirds by exposing them to a short-day light cycle. While adipose storage was stimulated, exceeding that typically seen in wild birds, other aspects of the migratory phenotype were unchanged. Of particular interest, the rate of lipid export from excised adipose tissue was nearly halved. This is in contrast to wild migratory birds in which lipid export rates are increased. These data suggest that exposure to an altered light cycle only activated the lipid storage program while inhibiting the lipid transport program. The factors governing lipid mobilization and transport remain to be elucidated.