It’s great that so many people are interested in providing nest boxes for Bluebirds, and because of these efforts Bluebird populations are extremely robust. We encounter customers, though, that ask a lot of questions they would have the answer to if they just monitored the nest box a little. We do not mind answering the questions, it’s very much part of the job.
Most of the time when we mention to a customer they should consider monitoring the box their response is “I don’t want to disturb them or scare them away”. If done properly neither of those things will happen. Not only is it interesting and a great nature and biology lesson, you can predict within a day or two when the babies will leave the box. And another reason to monitor is you may actually keep something bad from happening to the babies. I’ve often told customers of the time my son, who I taught to monitor, discovered one of our boxes with four two day old Bluebird babies was infested with ants. In just 48 hours, since the last monitoring, ants had found the newborn babies and were likely going to consume them given enough time.
We carefully removed the babies and placed them in a little box, then removed the entire nest from the box while the female watched from a nearby tree limb. We first cleaned all the ants out of the now empty nestbox and made sure no more would climb the pole. Then we constructed a rather poor replica of the nest using their preferred nest material pine straw. After the nest was back in the box we then removed all the ants from the babies by using a drinking straw to blow the ants off and then placed them back in the box in the clean nest. In all it took us about 20 minutes. The female returned to the box about 10 minutes after we completed the cleaning. Even after removing the nest and handling her babies the female came right back to them because the instinct to raise her young is that powerful. So, monitoring which really just consists of taking a peak for a few seconds will definitely not scare the birds away. Bluebirds tend to be quite tolerant of our presence. Usually they patiently watch as I monitor. Once in a while they will swoop at you clicking their beak in protest. But they will not abandon a nest because of brief looks in the box.
Monitoring Tips
Observing from a distance is important monitoring, too. Seeing bluebirds come and go is an indication they are showing an interest in choosing the box. If you see the pair on and in the box take a moment after they leave to go look inside. You will likely observe nest building at some point. Pine straw and fine dry grasses are the preferred nest material.
Bluebirds tend to lay eggs in the morning hours. The female will lay one per day until done, usually between three and six. Four and five eggs seem to be the most common numbers. She will not begin incubating until all the eggs are laid. So, at this stage I would recommend monitoring in the afternoon so as not to disturb egg laying in the morning. Or, again, if you see the female exit the box take a moment to go look. Take notes. It’s helpful to increasing your knowledge of the process.
When I monitor and see 4 eggs and she is not incubating yet that tells me she has probably one egg to go. I will make note of the date because we know Bluebirds incubate for 12-14 days and then should see babies.
Once I am certain she is incubating I do more monitoring from a distance. If you see the female exit the box and fly off that’s a perfect time to approach and take a look. Be gentle and quiet. I like a box that has a door that opens down as opposed to up. It is so much easier to monitor in a subtle way. I also take pictures to share with people.
Eggs laid before incubation.
Fledglings days after hatching.
Fledglings about a week after hatching.
Now the babies have hatched and I’ve noted the date because we know the babies will take about 14 days to develop and be ready to leave the box. This is known as the fledgling period.
I will monitor daily until by my calculations tell me there are just 2 or 3 days to go until they fledge. At this stage of their development the babies may be fearful enough to want to get out of the box if you open it. I monitor from a distance watching the parents as they make repeated trips with food to satisfy all those appetites.
Hopefully, the calculations are right and you may get a chance to see babies fledge. You will see more animated behavior from the parents as the first and second babies are about to come out for their first flight. Do not be alarmed if all the babies don’t fledge at the same time. It may take several hours for all to fledge.
For more information about Bluebirds and monitoring please visit the National Bluebird Society website. http://www.nabluebirdsociety.org/bluebirdfacts.htm