A Sample of Activity,
On a Bluebird Trail, During a Summer Nesting Season.
by Jack Saltes, Tricia Hagen and Jeri Webster
I saw the first pair (male and female) of returning bluebirds on Monday morning, 3/15/10.
The birds are now looking for food and focusing on staying fed. They will also begin to pair up. As the weather warms more consistently, they will look for nest sites (boxes) and begin to prepare nests for raising their young. Usually, the first nests will be built in early April, depending on the weather.
Of the eighteen boxes, ten have different stages of nesting activity occuring (56%). The bluebirds are certainly off to a fast start.
Above average temperatures in late March and early April have contributed to early nesting activity of the park bluebirds.
With the mild, warm temperatures over the last few weeks, bluebird nesting activity has begun, much earlier than past years. In fact, the first bluebird egg of the season was observed in a box during monitoring on April 11. This is the earliest eggs have ever been observed, in any boxes, in the past several years.
Weather though is always a big factor in early bluebird nesting success. Any cold weather, especially at night, over the next month, will certainly put bluebird eggs, and especially babies, at risk. If the weather remains relatively mild, even seasonal,
nesting success of the first broods of the season will be good.
Nest boxes that are not vented or where the open venting is insulated at this time of years helps to retain heat and helps nesting babies.
There has been alot of bluebird activity in the past week. Eight boxes now have full complete nests and eggs are already being laid in a few of them. One nest had 5 eggs and another nest had 2 eggs. We are hopeful that all full nests will have eggs by next Sunday. This is the earliest start to nest building and egg-laying in the several years of monitoring bluebirds in the park. Cold temperatures in the early spring, when the babies first hatch and are featherless, is a very vulnerable time for them. We are hopeful for continuing warm spring temperatures. Quite the bluebird start!
There have been many bluebird eggs laid in the past week,15! Most nests have a clutch of five eggs.
One nest had four white eggs. Bluebird eggs are light blue and rarely white. White bluebird eggs occasionally do occur, as observed in one box this week. Female bluebirds sit on the eggs incubating them for a period of 13-14 days. The first babies should start to hatch within two weeks. Hopefully, we will see more nests and eggs during this time too.
Two of the nesting boxes are being used by swallows. Sometimes there is competition for the nesting boxes. Occasionally, you will see the birds perched on top of the boxes or near by them, staking out their territory.
The bluebirds have been busy! More boxes are being used by bluebirds who constructed more nests during this week. The high nesting activity reflects the increased population of bluebirds in the park. Enjoy seeing them on your hikes in open areas of Donald Park.
The first babies hatched in one of the boxes and this is the earliest hatch of bluebirds, in the park, since the trail was started several years ago. Baby bluebirds are fed a high nutritional diet of insect larvae and insects, by both parents, for 16-22 days at which time the babies will grow big enough to fledge (leave the nest boxes). Insects not only have a high nutritional value they also provide water for the babies.
Again this week, more nests have been built and more eggs have been laid. Another nest of eggs hatched as well. We had concerns, about the babies that hatched the week before, might have been lost to the cold nights we've had this past week. Happily the babies have grown and are doing well! A photo of them is included. They have grown and have downy feathers now.
With so many eggs, many more babies will be hatching over the next two weeks. We hope seasonal weather and temperatures return soon for the growth and survival of these first bluebird broods. The bluebirds will be off to a great start if they do.
The first five baby bluebirds of the year fledged this past week. We should see alot more babies over the next few weeks,
as many of the twenty-six eggs left finish hatching. There have been some egg losses in a few of the boxes. Despite the nesting failures in these boxes, the bluebirds seem to have moved to nearby boxes to try again.
Seven more babies fledged this week bringing the total to twelve for the season. In just one week, one box had a new nest and three eggs. Wasting no time, the bluebirds built their second nest. Four days later they began laying eggs.
Some of the nests/eggs suffered egg losses due to wrens. Pugnacious wrens can be very territorial and aggressive. After bluebird eggs are laid, a wren may poke holes in the eggs, remove them and begin building their own nest. Having bluebird nesting boxes at least 200 feet away from woodlands, prime wren habitat, would be helpful to discourage wren competition. Wrens are the primary competitors for bluebird nest boxes in the park. Many boxes certainly will be moved further away from woodlands once the upland site is restored to prairie as part of the dredging project.
Many of the eggs have hatched in the past week: twenty-four babies! Despite the heat and rains over the past week, all the babies seem to be doing well. If they all fledge, it will be a great start given these are the first broods. Bluebirds usually have two broods during the season. If you are hiking the park, you'll be certain to see many bluebirds in the weeks ahead.
Many baby bluebirds fledged in the past ten days bringing the total fledged, for this year in the Park, to 28! The five babies left are big and will soon fledge too.
After the baby bluebird fledge, we clean out the flattened nests from the boxes, allowing new nests to be built. This time of year brings us in between broods. Some new nests have already been started.
We thought we'd have more fledglings by this time given the fast start but wren and sparrow competition has been fierce this year. It has been a rough ten days for some of the bluebird pairs. It is a time of the nesting season that wrens and sparrows are very aggressive in trying to claim some of the bluebird nesting boxes. They peck and toss eggs and tiny babies out of the boxes and can harm adult bluebirds as well. Sadly we found one box missing all the eggs and a dead female bluebird; a few boxes with eggs gone or on the ground and another box with the babies on the ground below the box.
Next year, we will certainly be moving bluebird boxes further away from wooded areas and into the open prairie area once the upper site is restored. This should reduce wren/sparrow competition and help in bluebird nesting success. Bluebird nesting success is predicated on good bluebird habitat, which is usually open, non-wooded areas. The restored upland site should provide just that next year.
Bluebirds are now starting a second round of nests and laying eggs. There are usually 3-4 eggs in the second clutch. By mid-July, we will know how many second broods and fledglings we will have. Blue-bird nest building usually ends by the second to third week of July so that babies are hatched in August and thus have plenty of time to grow, fledge and get big enough for fall migration.
Last week ( 6/16) we noticed three newly born babies that were thrown out of the nest box by wrens. They were directly below the box, with upset parents in the nearby trees. Two babies died, but one, while injured, was still moving and we returned it to the nest. We hoped that the parents would help it recover. Recover it did! That one baby bluebird had survived and had grown significantly in the course of the week, with two feeding parents. We were very heartened to have been able to have saved at least one bluebird. It is always inspiring to see parent bluebirds so faithful to their young, whether it is one baby or five.... although one is certainly alot less work.
The wrens have been fierce competitors for nesting boxes this year and definitely have had an effect on bluebird nesting success.
Egg and baby losses have also occurred. By this time of year we would have expected the total feldgings to be closer to 40-50 rather than the current 30. Nevertheless, we are pleased we are having at least an average year and plan to move nest boxes next season to reduce wren competition.
Bluebirds will finish nests/egg laying within the next ten days since any bluebirds hatched will need to feldge by the end of August for them to grow big and strong enough in September for autumn migration.
Bluebird nesting activity has significantly dropped off with only two active nests at this time. More bluebird eggs were lost to wrens over the past two weeks. We'll be checking boxes through mid-August. We sure hope to fledge at least 40+ bluebirds this year, which would be an average year, looking back at past years records.
Both the male and female adults are busy feeding all the fledglings that have left the nests. They are feeding their offspring a highly nutritional diet of insects and insect larvae.
Bluebirds are done nesting and will now continue to feed the young hatchlings. The first brood (May/June) of early spring babies will leave their parents in the summer. But the babies from the second brood (July) will stay with their parents through the winter.
by Jack Saltes, Tricia Hagen and Jeri Webster
Early this morning ( 7:30 am-8:30 am) there were about a dozen bluebirds hanging out on the edge
and around the prairie looking for insects and moths which are bountiful with all the goldenrod and asters in bloom right now. It's a great time to see so many of them before they migrate, especially now that many of the trees have lost all their leaves -- you can see many bluebirds in them. The upper site got brush-hogged and the Parks Dept. did a really great job. Really opened things up so you can see all the bird activity flying about. It's always pretty exciting and very heartening to see so many bluebirds all at once.