Final answer:
Gulls, ducks, and geese can stand on ice without freezing their feet due to a counter-current heat exchange system in their legs, which keeps their feet at the right temperature. Their water-repellent feathers further insulate them against the cold, whereas soapy water, with reduced surface tension, cannot provide the same protection.
Step-by-step explanation:
Gulls, ducks, and geese have a unique adaptation that prevents their feet from freezing while standing on ice. This adaptation involves a counter-current heat exchange system within their legs. Warm arterial blood that flows from the body core down to the feet is located very close to the veins carrying cold blood back from the feet to the heart. This system allows for the heat to be transferred from the warmer blood to the cooler blood. As a result, the blood reaching the feet is cool enough to prevent the feet from freezing, but not too cold to cause frostbite. Moreover, this adaptation maintains the internal body temperature of the birds, allowing them to stand on ice without their body temperature dropping significantly.
In addition, the properties of water and the water-repellent nature of their feathers ensure that water does not wet their feathers and they remain insulated against cold temperatures. Unlike soapy water, which reduces surface tension and may penetrate their feather layers, natural water tends to bead up and roll off due to the oil in the bird's feathers. This oil is produced by a special gland and spread over the feathers by the bird's beak, helping to keep the bird dry and buoyant.