2010 Bluebird Blog
The Bluebirds and Tree Swallows for the past two weeks have been in full production egg laying mode. There are, as of May 31, 2010 68 eggs being incubated at the Retzer Nsture Center. Bluebirds account for 21 of the eggs in 5 boxes. The Tree Swallows have a whopping 47 in the remaining 10 boxes. Tree swallows tend to lay more eggs, as many as 7 eggs in a nest and the typical Bluebird nest will have 5.
The Bluebirds have bounced back after the devastating loss of 20 Bluebird chicks the second week of May due to driving rains and temps in the 40's. Every nest box at Retzer has eggs being incubated in it. The Bluebird nests the second time around seem to be fuller and larger than average. Tree Swallow have lined their nests with plenty of feathers. Next week the air vents on the boxes that are closed during spring will be reopened to allow for ventilation.
Last weeks cold rainy windy weather was too much for the Bluebird chicks. The wind blew rain in thru the entrance hole soaking the nests and causing the chicks to die of exposure. When the nesting material gets wet the parents can not make enough body heat to keep the chicks warm. Subsequently the little ones die. The parents remove the babies from the nest boxes leaving an empty cold wet nest. I removed almost all the nests from the Nature Centers boxes. It is still early in the season so hopefully the adults will again start the nest building process which leads to mating and egg laying. We lost all 20 Bluebird chicks last week. A sad reality, but something that has happened for thousands of years. They will rebound as they always have. Keep the faith in nature correcting itself.
It's late April and 5 of the 15 boxes monitored already have Bluebird nests in them. The bluebirds were first spotted at Retzer the second week of March, with nest building activity beginning the first week of April.
All 15 of the boxes have gone under a rehabilitation in the last two years with new roofs added to some and door modifications to others. There are 5 brand new boxes and 3 new box locations at Retzer since 2009. The vent holes in the boxes have been covered with a slat of wood. This will keep out the cold spring winds. In early June the slats will be turned to alow ventilation during the warmer summer months.
Bluebirds build a tightly woven nest of only dried grass. The nest has a circular cup where the female will lay one egg per day for 5-6 days. She will lay an egg usually early in the day and leave the nest soon after and not return to the nest until the next morning. Both the male and female will take turns incubating the eggs only after the last egg is laid. On a colder tempature day she may not lay an egg so it can take up 10 days for her to lay all her eggs. The first couple of eggs can easily lay in the nest for over a week before they are incubated. Bluebirds can have as many as 3 broods in any one season. But generally around this part of the country she will lay 2 sets of eggs. After the first brood of chicks have fledged (flown from the nest) the old nest will be removed and the whole nest building, breeding cycle begins again. On occassion a bird from the first brood will stay on and help care for the second set of chicks. Usually this is a female with strong parenting genes.
Tree Swallows will also build there nests in the boxes. Both the Bluebird and the Tree Swallow are cavity nesting birds. Tree Swallows will build exactly the same type of nest as bluebirds using only dried grass. No sticks, twigs, leaves or trash will be used. However when the Tree Swallows lay their eggs feathers will be added to the top of the nest. Tree Swallows will lay from 6-8 eggs in the nest and will rarely lay a second set of eggs. Tree Swallows compete for nesting sites with the Bluebird but do not compete with the Bluebird for food. The Tree Swallow usually catches there food while flying and the Bluebird will sit on a low tree branch, post or tall weed and hunt bugs on the ground. Bluebirds eat a lot of spiders especially during the early spring when there is a limited number of insects on the ground.
As of April 21st 5 boxes had nests in them with 15 eggs total and 5 of the eggs were being incubated.
As of Monday night April 26th, 2010 there were 6 Bluebird nests with 20 eggs and all 20 were being incubated.
2009 Bluebird Blog
The blue bird boxes have been monitored since the first week of April. At that time we had installed 3 new boxes and moved several boxes to new locations to make better use of the land available. We will be monitoring 15 boxes on the Retzer Nature Center property for the 2009 season.
The first sign of blue bird activity was recorded the second week of April with several boxes with full nests inside. The third week of April brought a surprise with 1 box having 5 blue bird eggs inside with indications that the eggs were being incubated. As of April 28th we had 3 boxes with full clutches of 5 blue bird eggs each all being incubated. One box had 1 blue bird egg inside. This box will most likely be revisited once each day with one egg being laid every day until there are 5 to 6 eggs inside. At which time the incubation process will begin by both the female and male blue birds taking turns sitting on and rotating the eggs. So as of April 28th we had 9 boxes with partial to full blue bird type nests inside with 3 of these boxes having eggs being incubated.
2008 Bluebird Blog
We have 11 Bluebird boxes that are monitored on a weekly basis from early April till some time in late August or early September. As of right now well actually Saturday the 10 of May we had all boxes with some sort of nesting activity. 9 boxes have signs of bluebird ownership and 6 boxes have bluebird eggs inside. For a total of 25 eggs as of Saturday. The females will lay 1 egg a day or so depending on the weather. She usually lays them in the morning and leaves right after laying. She will come back for about a week to 10 days and lay until there are about 5-6 eggs in the box. At that time she will start the incubation process which lasts about 2 weeks. Again depending on the weather. Longer during colder weather. the young will take from 18-22 days to fledge (fly) from the nest box. Again depending on weather and food avaiablity. After they fledge they are on their own. Last year at Retzer we had somewhere between 55-60 bluebirds fledge from the 11 boxes at Retzer. The bluebirds in southern Wisconsin will have 2 broods a year. The young from the first brood will sometimes help out the parents with the second brood especially if something happens to one of the parents.
Babies where born in boxes 10 and 11 this week. With bluebird eggs still in boxes 5-6-7 and 8. Tree swallow eggs in boxes 3 and 9 each having 2 eggs.
Good Day My Friends:
On Saturday the 24th of May I was joined by long time Bluebird monitor Harry Lemann. Harry has been monitoring the bluebirds at Retzer for 25 years. Now that's dedication! We found that all boxes are still showing signs of nesting activity. We now have 17 baby bluebirds with 20 bluebird eggs (15 are viable) inside the nest boxes at Retzer. One box has had 5 eggs in it for over three weeks. These eggs were cool to the touch which leads us to believe that the parents especially the mother has for some reason abandoned the nest site. 3 of the nest boxes are now claimed by Tree Swallows with 14 eggs in these 3 boxes. Tree swallows will only have one brood of chicks per season, so these 3 boxes may have bluebird's present for their second brood. A lot of the bluebird eggs should hatch sometime this week, based on how long they have been in the boxes, but with the cold temperatures early this week it may take a little longer for the incubation process to be completed.
Hello again bird lovers,
We now have 22 live baby bluebirds and 11 bluebird eggs in our boxes at Retzer. Tree swallow still claim 3 boxes at the nature center with several baby birds and a dozen or so eggs. The box with 5 eggs that were cold to the touch as reported in the 5-24 update now has 1 tree swallow and one new bluebird egg inside. As to what happened to the 5 abandoned eggs we do not know. 10 of the bluebirds should fledge (leave the nest) this week. The parents will watch over them and teach them the basics of hunting insects and how to get out of the weather and where to roost at night. This will happen over the next week or so. After that the young will be on their own. The nest boxes will then be cleaned out and the nesting process will begin again for the adult bluebirds. We clean out the boxes because the females will not claim a box with a dirty nest inside. Also the process of building a new nest excites the hormones of the birds and the egg laying process will begin again. She will lay no more than one egg a day for about a week. Usually a total of 5 will be laid for a clutch of bluebirds eggs.
The pictures were taken on Saturday May 31st 2008. They show an average bluebird nest with 5 pale blue eggs. Note the material used to make the nest. Only dried grass is used. No sticks, twigs, trash or any other material. Just dried grass. The tree swallow will make a very similar nest with the addition of some kind of white material. Usually feathers but sometimes soft tissue paper but almost always white in color which they use to line the top of the nest. Bluebird eggs are very similar in color to a robin's egg. The eggs are about the size of a mans thumb nail.
The photo showing the bird being held, should only be done by an experienced bird handler and is not recommended for anyone visiting the nature center. It was done this time to teach a group of children about bluebirds.
The third photo shows our box with a rare brood of only two birds. They are tightly packed inside the nest. You can see the start of flight feathers on the bird in the foreground.
Well the bluebirds were back into full egg laying mode last week. 21 new bluebirds eggs laid as of late Sunday July 6th 2008. 8 of the 11 bluebird boxes are now occupied by nesting/egg laying bluebirds. Box 8 has 4-5 fully developed Tree Swallow birds which should leave the nest this week. This nest box will be cleaned out late this week and hopefully taken over by a pair of bluebirds. Boxes 1 and 10 have no nesting activity at all.
Another Bluebird nesting season has come to an end here in Southeastern Wisconsin. At Retzer we had plenty of nesting activity.
We had the typical 2 broods of bluebirds this year. The first Bluebird eggs were laid in the fourth week of April and the last bluebird eggs were laid in the second week of July. Of the 11 boxes that were monitored at Retzer we had 108 eggs laid, 66 of which were Bluebirds, 23 Tree Swallows and 19 were House Wrens. 86 birds fledged (hatched, grew, and flew from the nest.) Of the 86 birds to fledge 44 were Bluebirds. We had 32 Bluebirds fledge from the first brood and a disappointing 12 from the second. We had 28 bluebird eggs laid in the second brood of which 16 were either not viable or were lost to predators. As to what ate the eggs we are not sure. Raccoons and snakes are the most likely culprits but we can never be sure.
The 11 nest boxes at Retzer were monitored weekly by a couple of different people. We got together on Saturday August 23rd 2008, compared notes and found almost no differences in our data.
One of the nest boxes will be moved this fall to get it farther away from other boxes and maybe an addition of one or two new boxes for better use of the land.
We await another spring for the return of the Bluebirds and another nesting season. Enjoy your Winter.