一只年幼的红肩鵟（Buteo lineatus）正在侦查周围环境，它张开喙主要是为了调节体温，栖息在

ile Red-shouldered Hawk (Buteo lineatus) is sitting, surveilling the area, and holding its beak open primarily to regulate its body temperature and cool down, on top of a black metal fence. Because birds completely lack sweat glands, they cannot sweat to dissipate body heat. Instead, they use several unique biological methods to stay cool on warm days. This is the avian equivalent of a dog panting. By opening its mouth and rapidly vibrating the moist, featherless skin of its throat (the gula), the hawk promotes rapid moisture evaporation to drop its core temperature. Juvenile Red-shouldered Hawks are commonly identified by having banded secondaries (flight feathers) rather than the intense black-and-white patterning of adults. They are known to be vocal, often heard calling before they are seen.