Complex sentence: Some studies on White-crowned Sparrows have suggested that prolactin is involved in the pre-migratory hyperphagia (feeding), fattening and "Zugunruhe" however others have found that prolactin may merely be associated with lipogenesis (fat accumulation).
Split into simpler sentences: Some studies on White-crowned Sparrows have suggested that prolactin is involved in the pre-migratory hyperphagia (feeding), fattening and "Zugunruhe". However, others have found that prolactin may merely be associated with lipogenesis (fat accumulation).