Birds trigeminal nerve

In birds, the trigeminal nerve appears to play a role in food selection. Starlings more easily accepted commercial feed treated with otherwise avoided coniferyl benzoate after bilateral section of the ophthalmic branch of the trigeminal nerve. Therefore, the trigeminal nerve may help to protect the animal by detecting plant defense compounds. Many of these compounds are astringent or irritating (Jakubas and Mason, 1991). 

Feeding repellents for pest birds are the most important application of chemical stimuli to manipulate bird behavior. Methyl anthranilate (Fig. 13.1) and dimethyl anthranilate, esters of benzoic acid, are found in concord grapes and are used as artificial flavorings. Starlings, Sturnus vulgaris, have an aversion to methyl anthranilate, which irritates the trigeminal nerve, and they feed less on food flavored with a variety of anthranilates. They avoid the more volatile anthranilates most. The odor is partly responsible for the effect contact is not necessary. In one particular experiment, only volatile compounds were aversive (Mason and Clark, 1987). If only anthranilate-treated food is offered, the birds will accept more of the flavored food than they do if they offered a choice between... 

It irritates skin and mucous membranes. In terms of chemoreception, it irritates the trigeminal nerve. Capsaicin binds to the vanilloid receptor subtype 1 (VRl). Birds lack this receptor. Since they cannot sense capsaicin, they eat and distribute seeds of red hot peppers. Medically capsaicin is used as painkiller (analgesic). 

Capsaicin is the active ingredient in commercial squirrel repellents. It is very common that squirrels raid bird feeders. To discourage them from doing that, bird seed can be shaken with powdered capsaicin preparations, so that it adheres to the surface of the seeds. The treated food is supposed to irritate a squirrel s mouth and trigeminal nerve. 

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