They're not light.
Last night when i took Carrie out i could hear deer browsing about in the underbrush: three, i'm fairly sure. Carrie eventually barked in indignation, and the deer seemed not to care. Later i came back out, turned on the light, and called for Carrie -- this did cause a bit of crashing around. Deer are loud.
This is also posted at http://elainegrey.dreamwidth.org/640612.html .