2011 BLUEBIRD REPORT – NEST CAMS ARE A SUCCESS!

The long awaited nest box cameras were installed in two song bird boxes near the Visitor Center in April 2011. Permission for the installation was finally obtained in November 2010. The severe winter of 2010-11 further delayed the installation beyond the target date of February when bluebirds begin seeking nesting sites for their first clutch of the season.

After researching the options it was decided to use a hard wired system for powering the cameras in the two nest boxes. A wireless system for each box using batteries or a solar panel was more expensive and likely to require more maintenance. The power/video lines are routed underground in single plastic conduit from the boxes to the Visitor Center. The signal from the boxes goes to a screen in the visitor center map room. The screen shows continuous live action from either of the boxes. The signal can be switched from one box to the other.

Tree swallows were the first to nest in one of the boxes. They built their typical straw and feather nest. The first egg was laid on May 12. A pair of bluebirds took up residence in the other box to have their second clutch of the season. Their first egg was laid on June 10. Observers of the action in the nest boxes found it fascinating. Visitors seem to spend more time viewing the nest cam than looking at the other exhibits. Even those who monitor nest boxes enjoy the view. Nest box monitors often open boxes and have tree swallows brooding eggs or young hatchlings. The tree swallows are very reluctant to leave their nest and seem frozen in place. While viewed brooding their eggs on the nest cam, the female tree swallow is in near constant movement turning her eggs to keep them at the proper temperature.

Many were involved in the nest cam project. The Friends promoted the idea and funded the effort. The bluebird team selected the site for the boxes and the vendor for the nest box/nest cam package. The Refuge staff dug the trench, laid the cabling and installed the inside display panel. A special thanks to the tree swallows and bluebirds that occupied the boxes and entertained so many visitors over the spring and summer. Hopefully they will remember to return next season.

2011 NESTING SEASON WAS GOOD BUT NOT A RECORD YEAR

The 2011 song bird nest box season was good but did not produce any nesting records. There were 141 boxes monitored during the year. The first egg of the season was laid rather late on April 12 by a bluebird. The last nest (house wren) fledged on August 13. The nesting (nests with eggs) totals were:

SPECIES NESTINGS

Bluebirds 71 Tree Sparrows 67 House wrens 5 House Sparrows 10

TOTAL NESTINGS 153

Although there were more nestings than boxes, not all nest boxes were used as some boxes hosted multiple nestings. Twenty one nest boxes did not have a nesting in 2011. Therefore, 85% of the nest boxes had at least one nesting. This is excellent versus the occupancy of nest boxes in my own yard. The notable events during the nesting season were:

O A black bear pulled down one song bird nest box post near the bank of the Great Brook. This occurs every few years. Black bears have keen sense of smell but poor eyesight. All the nest boxes they have attacked contained hatchlings. The bear evidently smells the birds and thinks the nest box is a bird feeder that bears often raid. The bear finds little to eat and stops after destroying one box.

O Bluebirds laid white eggs in one nest box. These are the first white eggs observed since 2008. Over the years 11 bluebird nests with white eggs have been found in 503 nestings or slightly more than 2% of the bluebird nests. The eggs hatched and fledged. The bluebird pair did not attempt a second nesting. White bluebird eggs are shown in Figure 1.

O Bluebirds laid a 6 eggs clutch. This was first time since 2009. In a total of 503 bluebird nests only 8 had six eggs or about 1.5%. All the eggs hatched and fledged. The bluebird pair did not attempt a second nesting.

The summer interns had the opportunity to accompany either Lou Pisane or myself on a monitoring visit to the bluebird boxes. Some participated in multiple visits.

BLUEBIRDS HAVE ABOVE AVERAGE NESTING SEASON

For the fifth time in six years more than 200 bluebirds fledged from Great Swamp National Wildlife Refuge (GSNWR) bluebird nest box trail. In the 2011 season 228 bluebirds fledged versus the 254 bluebirds that fledged in the record year of 2010. For the third time in four years there were more bluebird nestings than tree swallow nestings. Chart 1 presents a comparison of bluebird and tree swallow nestings (nests with eggs) for the last 11 years. Chart 2 compares fledgling production for the two species.

Below is a comparison of the 2011 bluebird breeding season with average for the 2004-11 season as well as the best results for that period:

2011 Average Best

Bluebird Nesting Pairs 42 38 45

Bluebird Nestings 71 63 82 Eggs Laid 290 261 337 Fledglings 228 203 254

Bluebird Eggs That Fledged, % 79 78 90 Pairs Attempting Second Nestings, % 64 60 81 Failed Nestings (No Fledglings), % 15 18 8

2 As shown in the above comparisons, bluebirds in 2011 did better than average in every category. However, none of the 2011 results set a record. There were more bluebird nestings started in May than in April. When this happens, there are not as many second bluebird nesting attempts. Nest box predation was about half of the average rate. However, abandonment (eggs fail to hatch) and other failures were somewhat higher than average.

TREE SWALLOWS HAVE EFFICIENT NESTING YEAR

Tree swallows had 67 nestings in 2011. This is the lowest number of tree swallow nestings as shown in Chart 1 for the 2001 to 2011 time period. In spite of the reduced number of nests, tree swallows fledged 264 young in 2011. This was greater than the numbers fledged in the previous 3 years as illustrated in Chart 2. This seemingly paradox is explained in part by the number of successful nests (nests that produce fledglings) in 2011. Below is a comparison of 2011 nesting success versus the 11 year average:

Year 2011 Average

Predated Nests, % 12 16 Abandoned Nests, % 5 7 Other Failures, % 4 4

Total Nest Failures, % 21 27

The wet weather conditions during the spring and summer of 2011 provided an adequate food supply for predators as well as foraging tree swallow parents. Raccoons are the most common nest box predator. Evidently they had sufficient prey in 2011 without needing to raid as many nest boxes. The wet weather that continued through most of July also helped tree swallows find sufficient flying insects to feed their hatchlings. Tree swallows only raise one clutch a season but will renest in June if their first clutch fails. Many nests started in June are abandoned (eggs never hatch) as adults cannot find sufficient food in conditions that are usually very dry. Lack of food can also lead to clutch starvation (other nest failures). In 2011 seventy percent of the clutches started in June were successful. In the previous 4 years only 50% of the tree swallow nests that started in June fledged young.

The good weather conditions also spurred egg production. Tree swallows typically have first clutches of 5 or 6 eggs. However clutches ranging from 2 to 7 eggs have been observed in the Swamp. In 2011 the average tree swallow clutch was 5.1 eggs versus the 11 year average of 4.9. There were 3 three tree swallow clutches with 7 eggs. All the eggs in these clutches eventually fledged.

HOUSE WREN NESTING ACTIVITY RETURNED TO NORMAL

For the first time in at least 10 years house wrens failed to fledge any young from the nest boxes in 2010. This season house wren nesting activity returned to near normal as there were five nestings with a total of 22 fledglings. One of the five house wren clutches failed to hatch. This was likely due to overheating of the eggs. House wrens also built their stick nests in 4 other boxes but did not lay any eggs in them. Wrens are known for building more nests than they ultimately use for nesting. The 22 fledglings are below the average of 30 house wren fledglings in the years from 2001 to 2009. All of the 2011 wren nestings were in boxes that house wrens had not previously used.

3 The house wrens nested in three nest boxes. They had second nestings in two of the boxes. House wrens prefer to nest close to cover. We plan to move one of the boxes further away from the tree line to discourage wrens from nesting. Wrens built nests in two boxes following the successful fledging of bluebird clutches. The two bluebird pairs did not attempt a second nesting in the pair of boxes.

HOUSE SPARROW NESTINGS SPIKED IN 2011

Nesting attempts by house sparrows vary significantly from year to year. When it seems they are nearly eliminated, the sparrows surprise with a spike in nestings. As shown in chart 3, there were 10 nestings in 8 nest boxes in 2011. This is the third highest total for house sparrow nestings in the 2001-11 time periods. All 8 nest boxes used by sparrows were within site of an occupied building. One pair of nest boxes had three house sparrow nestings this year and one in 2010. This pair of boxes will be relocated this fall to a site less likely to be attractive to house sparrows.

House sparrows also known as English sparrows are not true sparrows but belong to the weaver finch family. They were introduced from Europe and have colonized the Americas. They are aggressive cavity nesters that can kill and/or displace native birds such as bluebirds and tree swallows. As is the Refuge practice, all the house sparrow nestings were disrupted to prevent any house sparrows from fledging

IMPROVEMENTS PLANNED FOR 2012 SEASON

Conical predator guards will be added to several pairs of boxes that suffered repeated predations during the 2011 season. These guards have been successful in reducing mammalian predation. As is done every fall, a number of nest box pairs located in areas no longer attractive to bluebirds due to changes in vegetation or due to house sparrow infestation will be relocated to what appear to be more productive sites. One pair of boxes will be relocated to the large field across Pleasant Plains Road from the Visitor Center. This field is scheduled to be cut periodically and was attractive to bluebirds in the past before it became very overgrown.

Any nest boxes or box tags damaged during the season will also be replaced in the fall. The plan is to monitor a maximum of 141 song bird boxes during 2012.

Many thanks to Jennifer Dawson, Nancy Felicito and Lou Pisane (see Figure 1) who monitored nest boxes and reported their findings on a weekly basis during the 2011 nesting season. This was Jennifer's first year as a nest box monitor. She plans to return for the 2012 season. Thanks to the group for their help in maintaining and modifying the nest box trail during the off season. Thanks to Paul Ford for building new boxes and repairing others for the trail.

Leo Hollein August 16, 2011

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CHART 1 – HISTORY OF BLUEBIRD AND TREE SWALLOW NESTINGS

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CHART 2 – BLUEBIRD AND TREE SWALLOW FLEDGLINGS

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CHART 3 – GREAT SWAMP HOUSE SPARROW NESTING HISTORY

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FIGURE 1 – WHITE BLUEBIRD EGGS ARE FOUND IN 2% OF NESTS

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FIGURE 2 – 2011 BLUEBIRD NEST BOX MONITORS (LEFT TO RIGHT – LEO HOLLEIN, NANCY FELICITO, JEN DAWSON AND LOU PISANE)

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