A malar stripe is likely to be found on which bird?

A malar stripe refers to a distinct stripe that runs along the cheek area of a bird, typically found in raptors. This stripe is often associated with enhancing the animal's visual acuity by reducing glare from sunlight and increasing contrast, which is vital for hunting.

The peregrine falcon is known for its prominent malar stripe, making it easily identifiable. This stripe helps to give the peregrine its characteristic facial pattern, which sets it apart from other falcon species. The dark markings contrasting with the lighter face enhance the bird’s appearance and can assist during flight by breaking up its silhouette, which is useful for both predation and evasion from other birds.

While other birds like the gerfalcon may have variations of facial markings, the specific and prominent malar stripe is most prominently featured in the peregrine falcon. The terms "jack" and "tiercel" refer to specific age and gender classifications rather than distinct species, which makes them less relevant in identifying a bird with a malar stripe. Hence, the best answer pointing to the presence of a malar stripe is indeed the peregrine falcon.