[pixelbath]

TFA addresses this directly:

> For the crows, the spikes seem purely structural, a material used to fashion a solid foundation. In both crow nests, the wires were incorporated into the base–interwoven with the points facing inward, below where a softer nest cup would sit. But for the magpies, there was an additional layer of intrigue; not only were the birds using the spikes to build nests, but it’s possible they were also employing the devices for their intended purpose—to ward off other birds.