It’s been twenty-three days of incubation now and getting close to hatch time. Reports of the average time for incubation generally call for 27 to 28 days. However, reported ranges of incubation times span from 25 to 30 days. Now that we’ve been closely following this pair for six years, it would seem reasonable that we could narrow that range down by calculating previous incubation times for this pair. The problem is that because of nest failures and egg losses or abandonments we only have two definite times for the first laid egg and two less definite times for the second laid egg.
For the first laid egg, we have 27 days, 3 hours (2017) and approximately 26 days, 10 hours (2018; approximate because we don’t know exactly when it was laid overnight). So the average is a little shy of a full 27 days. This year’s first egg was laid at 8:21 am on May 18th. A full 27 days would be the morning of Sunday, June 14th. It’s also interesting to note that, for this pair, all four recorded hatch times occurred between midnight and 6:00 am. So sometime in the early morning of Sunday looks promising.
We can do the same for the second egg. The records are a little sketchy but it appears that a reasonable estimate for incubation time is 26-1/2 days. It would seem the earliest we could expect a hatch would be Monday night or Tuesday morning.
Now all that’s left is waiting to see if the loons show consistency or decide to make a fool of me. Having come to know these two, I’m thinking the smart money is on the latter.