Q  In late summer I get swarms of hummingbirds at my feeders. How can I estimate how many hummers I have in total? Can I calculate by how much nectar I put out?

A  The amount on nectar is not a
reliable way of estimating, because of evaporation, dripping, and usage by
other birds and animals.
Experts who have banded and colormarked birds in busy backyard feeding areas have suggest this formula. First count the largest number of hummingbirds you see at any one time. Then multiply that number by six. You might be surprised how many hummingbirds you are actually feeding. Another way to estimate is to count al the hummingbirds you see for half an hour. That's about the interval after which the first hummingbirds you counted come back for another drink. Larry & Terrie 
