Diel prey distribution patterns drastically alter their availability to predators, but how that affects predator behaviours remain poorly understood due to limited data overlap. Using spatiotemporally concurrent tracking of two sympatric seabird species and their fish prey, we reveal how diel prey distribution patterns influence foraging behaviour. The seabirds invested greater effort during twilight, peaking at dusk, with 25-80% enhanced efficiency. Prey vertical migration increased their abundance near the surface at night with 20%, but number of aggregations showed diel asymmetry, peaking at 140° azimuth before decreasing with 25% in 20°. These dynamics created elevated foraging windows in late afternoons, with extended duration of high efficiency and effort (56–70% of dives). The deep-diving predator Uria aalge followed prey depth linearly, while the comparatively flight-adapted Alca torda was more sensitive to prey depth and aggregations. We provide novel details of diel prey behaviour shaping predator foraging, demonstrating how morphological adaptations drive niche differentiation.