This magpie is a builder; the branch represents a simple piece of construction material to build his nest. These birds are known to be quite intelligent, and it is evidenced even more in how they construct their nests. Unlike most birds, many will build domed nests as opposed to open-topped nests. Moss and mud hold the branches and other materials together, and it will often take several weeks to build. I think when you really start to learn and observe what wildlife does to maintain their day-to-day operations, you can really appreciate how similar to humans they can be.
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From @mmckinneyphoto13