Hearing how does it benefit raptors?

Raptors are as mentioned in previous blogs have keen eyesight in which they rely on in hunting. 

Although, some raptors such as owls you find morphological adaptations, such as having facial disks, as well as the positioning of the ears that allow them to locate prey (Singheiser, et al, 2010). But aside from the owls’ adaptations, sensitive acoustic hearing that allows them to locate prey isn’t exclusive to owls; this form of detection is also seen in diurnal raptors (Rice, 1982).

Fig 1. diagram indicating properties related to hearing in Barn owls and their position (source from

All About Owls)

Firstly, owls (Strigiformes) being nocturnal hunters their vision allows them to detect movement though it is limited; therefore to precisely locate and capture prey they are guided by acoustic location (Hausmann, et al 2009). For example, barn owls and their dish-shaped face allows the sound of fairly low frequencies to be heard, as well as the positioning of the right and left ears being asymmetric helps the owl orientated and locate their prey in the dark (Singheiser, et al 2010, Payne 1971, Hausmann, et al 2008).

Fig 2. Shown in this figure is a mouse with paper tied and trailed behind it, determining whether the owl locates prey by sound or sight in the dark (sourced from Konishi, M. 2012 )

Secondly, acoustic detection and location are also seen utilised by diurnal raptors such as the marsh hawk which detect small mammals concealed in long the grass, even though it would play a larger role in nocturnal raptors (Rice 1982). Though the marsh hawks have facial ruffs and display quartering behaviour (not typical of Accipitridae but seen in owls), they do not show the accuracy demonstrated by the owl (Payne 1971, Hausmann, et al 2008). As mentioned by Rice (1982), some tested marsh hawks would strike several times in the attempt to flush out or would miss their target.

This blog is not to say all owls and other raptors have similar acute hearing or accuracy with acoustic location.

Reference:

Hausmann, L., Plachta, D.T.T., Singheiser, M., Brill, S. & Wagner, H. 2008, "In-flight corrections in free-flying barn owls (Tyto alba) during sound localization tasks", Journal of Experimental Biology,vol. 211, no. 18, pp. 2976-2988.

Hausmann, L., von Campenhausen, M., Endler, F., Singheiser, M. & Wagner, H. 2009, "Improvements of sound localization abilities by the facial ruff of the barn owl (Tyto alba) as demonstrated by virtual ruff removal", Plos One, vol. 4, no. 11, pp. e7721. 

Payne, R.S. 1971, "Acoustic location of prey by barn owls (Tyto alba)", Journal of Experimental Biology, vol. 54, no. 3, pp. 535-569.

Rice, W.R. 1982, "Acoustical Location of Prey by the Marsh Hawk: Adaptation to Concealed Prey", The Auk, vol. 99, no. 3, pp. 403-411.

Singheiser, M., Plachta, D.T.T., Brill, S., Bremen, P., van der Willigen, Robert F & Wagner, H. 2010, "Target-approaching behavior of barn owls (Tyto alba): influence of sound frequency",Journal of Comparative Physiology A, vol. 196, no. 3, pp. 227-238.