On a regular basis, it's important to peek inside the nestbox, and watch the activity around the box, to see how its residents are doing. If there's a problem, you can try to solve it. Monitoring is interesting, and it also increases the likelihood of a successful clutch.

Bluebirds are tolerant of humans. Opening the box will not hurt the birds, and some brooding mothers will even remain on the nest when you look inside. Songbirds do not have a good sense of smell, so leaving your scent will not deter them.

Bluebirds lay their eggs in the morning, so the best time to do a quick check is in the afternoon. You can wait until you see the birds leave the nest, and then monitor the box quickly. If the box opens from the front or side, you can use a small mirror to see inside the nest better. You can monitor every day, or at least once a week. The eggs take about two weeks to hatch, and the hatchlings take about three weeks to fledge (see nesting behavior). To keep the nestlings from fledging prematurely, it may be best not to monitor after the 14th day of hatching. After the bluebird chicks have fledged and left the box, remove the old nest. Western bluebirds usually have up to two broods during each breeding season from late March to late August.

Depending on where you live in San Diego County, some other native small cavity-nesting birds that you might attract to your nestbox are: Bewick's or House Wren; Oak Titmouse; Mountain Chickadee; Ash-throated Flycatcher; Violet-green or Tree Swallow; and possibly White-breasted Nuthatch. Non-native House Sparrows might also be attracted to your nestbox. House Sparrows can ruin bluebird eggs and young, and may even peck an incubating female to death. House Sparrows are not protected and can be trapped and their eggs and nests removed.