Bluebird Trail at Derby Hill

August 18, 2015
It’s nearing the end of summer; the birds have quieted down, most of them finished with their nests and now feeding fledglings or preparing to migrate south for the winter. Some migrants have already started their journeys.

At Derby Hill in early August, I checked the nest box with the house wren nest one last time, on August 7th. The eggs had just hatched about one day prior – the nestlings were very tiny, with some natal down and no pin feathers showing yet. House wrens build their nests out of twigs, and tend to stuff the entire nest box (or natural cavity) full right to the top. The nestlings were at the very bottom of this very tall, twiggy nest.

The bluebirds and the tree swallows are all finished for the year, and hopefully we’ll have the same pair of bluebirds return next year, and if we’re lucky, we’ll have two pairs of bluebirds!

Here are some photos of the house wren nest:

I’m looking forward to some fall birding, trying my best to identify those tricky fall warblers! 😉

Linnea Rowse

July 25, 2015
This was one of the last nest box checks of the season – the second nest of bluebirds was partially fledged, with only 3 huge nestlings remaining in the nest box. I just cracked open the box to look, and from what I could see one of the three was a male (deep blue color on the wing feathers; females would have a paler blue color to those feathers). The other two were deeper in shadow and I couldn’t see them well enough to tell – just well enough to count heads.

The last active nest of tree swallows fledged the previous week – I’d been out of town so Steve Soule did two weeks’ worth of nest checks. He watched the bluebirds and tree swallows grow. The rest of the boxes were empty with the exception of two. An exciting addition to this summer’s users of the boxes, and ok because it’s the end of the summer so they’re not competing with the bluebirds, there’s a house wren nest with 5 eggs in it! The box is stuffed full of small twigs, and the nest cup interior is fairly deep. One other nest box at the top of the north lookout hill has a half-built house wren nest – likely a different pair (the nest with eggs is at the south lookout).
I didn’t have a camera with me this time, but I’ll try to remember it next week, so you all can see the house wren nest!

Best birding wishes in the heat of the summer,
Linnea Rowse

May 26th, 2015 – Derby Hill Bluebird Trail update:
In the midst of this very busy spring, the bluebird trail has been seeing lots of activity!! (My apologies for not giving you all an update blog for the past 2 weeks that I checked the boxes.)

We have bluebirds using one of the nest boxes – the eggs hatched on about 5/16 – I checked the box on 5/17 and the 5 nestlings looked about 1 or 2 days old. Just this Monday (5/25) when I checked again, the nestlings had grown substantially! They were about 8-10 days old. Eastern Bluebirds typically fledge 16 to 21 days after hatching, so by next week they may be newly fledged, or ready to fledge. I’ll keep you posted. Here are a few photos:

Bluebird nestlings – day 1 or 2:


Bluebird nestling day 1 or 2. The white object is called a fecal sac – nestlings will usually defecate after the adults bring food, and the adults usually will carry this out of the nest to keep the nest clean.

Older (day 8-10) bluebird nestlings (there are at least 4 nestlings – can you count them all?):


The tree swallows have been very active as well – there are currently 9 boxes with eggs, but none have hatched yet. It will happen soon though!


Tree Swallow eggs (most of the nests have 5 or 6 eggs). Tree swallows line their nests with feathers, which is one easy way to tell apart their nests from bluebird nests before the eggs are laid.

When I approached one of the tree swallow boxes, an adult (the male) flew out of it, so I proceeded to open the box. I unexpectedly found the female still in the box – not actively defending the eggs, but rather she was off to the side and pretending to be dead (she wasn’t!). The female flew out of the box after a minute or so.
And last but not least, we had a great turnout for the bluebird trail guided walk during the Derby Hill bird festival – about 10 or 15 people joined me to peer into the boxes, and view many tree swallows. Thanks to all who joined me!

-Linnea Rowse

April 27, 2015
It’s been a relatively slow start to the spring – with cool temperatures and even some snow last week! I’d like to introduce myself first before writing a bit about the Derby Hill bluebird trail. My name is Linnea Rowse, and I’m a Field Conservationist for Audubon New York. My work focuses on getting private landowners involved in creating and maintaining young forest habitat on their land to help support the population of Golden-winged Warblers in Jefferson and St. Lawrence Counties, north of Watertown, NY. For the past year, I’ve lived very close to Derby Hill, and so I volunteered to monitor the bluebird nest boxes there this spring and summer. A little more about my background – I’ve lived in many locations across the country, working seasonal bird research jobs in between my undergraduate and graduate degrees. Most recently before moving to New York for this position with Audubon NY (and after grad school), I worked in Colorado for Rocky Mountain Bird Observatory, as a bird bander in the fall and a bird surveyor in the summer. Another job (back in 2009) had me making detailed behavior observations of Western Bluebirds in Carmel Valley, California. I loved handling the bluebird adults and nestlings – we banded each with unique color bands in order to track individuals and family behaviors. So monitoring the bluebird boxes here is a fun reminder of my time spent in CA with the WEBLs.

Last week, on 4/19/2015, only one of the 18 boxes had some nest progress. I suspect it is tree swallows building, though the nest wasn’t lined with feathers yet. The nest was fairly close to completion though – filling about half the box and with a cup forming on the inside. I hope to get back out to check in the next day or two since I wasn’t able to make it out this weekend. Other than the one nest, there was one box where a mouse seems to like eating acorns – evidence was there in the form of a few shells. When we cleaned out the boxes 3 weeks ago, the same box had had many acorn shells in it, leftovers from this winter.

Bluebirds have been observed at Derby Hill, though not (to my knowledge, at least) checking out the boxes yet. Spring is warming up though, and more songbirds are beginning to arrive. I’ll keep you all posted.

2014 Nest Season Reports

June 26
Good news! The Eastern Bluebirds have a new nest. Same pair? Different pair? It is impossible to tell unless the birds are banded, but they have built in the same box as before at the north lookout. The female did not flush when the box was opened; she sat tight on her 3 eggs. The second brood of the year is often smaller than the first, so this may be a complete clutch; we won’t know until next visit.

Tree Swallow season is almost over. Since the last visit, 39 Tree Swallows have fledged out of 7 nests. Thirteen nestlings remain in 3 nests and will probably fledge in the upcoming week. There are no eggs left. Unlike bluebirds, Tree Swallows have only 1 brood per season. Six baby birds growing up in a small box can make quite a mess (see photo). The used nests can harbor parasites and pathogens, so all of them were discarded at least 50 feet from the box and the boxes were cleaned out.

The House Wrens on the garage have fledged 7 young. This photo of a parent bringing food to the nest was taken last week by Liz Williams.

June 16
There are no active Eastern Bluebird nests right now. Tree Swallows are present in all stages of development, from newly hatched to almost ready to fledge. The 10 active nests have 49 nestlings plus 4 eggs that still could potentially hatch. Three of these nests should fledge in the next couple of days.

What do we check for this time of year? Paper wasps can build nests on the inside roof; these nests get carefully removed. The roofs had been soaped to minimize this problem, but 1 wasp built its nest sideways on the wall (see photo). Ants can invade the nest box. A ring of vaseline had been placed around each pole to prevent the ants from climbing up, but as the vegetation around the pole gets higher, the ants can climb up any grass blade that touches the box; the vegetation gets tromped down. Blowflies can lay their eggs in the nest material. The parasitic fly larvae feed on the blood of the nestling birds. Each nest gets lifted up using a pancake flipper and checked for blowfly larvae. Some of the larvae can get brushed out of the box to reduce their numbers, or in severe infestations, a new nest can be made by human hands to replace the infested one. The birds will readily accept their new nest. Thank you to Liz Williams for helping with today’s monitoring.

June 04
The Eastern Bluebirds have fledged; the family was nowhere to be seen. Hopefully, the parents will raise a second brood in the same or a nearby nest box. The nest box was cleaned out to avoid the build-up of pathogens and parasites. Some blowfly pupae were found in the nest (see photo). These blowflies (Protocalliphora sp.) are parasites whose larvae feed on the blood of nestling birds. They live in the nesting material and crawl up and feed on the nestlings mainly at night. They pupate in the nest material and emerge as adult flies that look similar to house flies. As horrible as that sounds, light infestations such as this one probably do the birds no harm.

Tree Swallows are hatching all over. Six of the 11 Tree Swallow nests have at least partially hatched. There are 33 very young nestlings and 24 eggs still being incubated. Two pairs of nest boxes have active Tree Swallow nests in both boxes of the pair, a very unusual occurrence. These birds require about 16-22 days between hatching and fledging.

May 26
The Eastern Bluebird nestlings are now about 14 days old. Today was the last time this box will be opened. Opening a box containing older nestlings could cause them to bolt out and fledge prematurely. After the young leave the nest on their own timing, the adult male will feed the fledglings while the adult female hopefully gets busy preparing for the second brood. She might re-nest in the same box or she might choose another nest site. The nest box will get cleaned out between broods to prevent the build-up of pathogens and parasites.

The Tree Swallows are now up to 50 eggs in 10 nests; clutch sizes range from 1-7. They can be very tolerant of monitoring – 3 of the females sat tight and did not flush when the box was opened. Other pairs were very defensive and dive-bombed the monitors. While not part of the Derby Hill bluebird trail, there is a wren house mounted on the garage; a pair of House Wrens has 7 eggs in their stick nest. Thanks to Mitch Nusbaum for helping with the monitoring.

May 19
The Eastern Bluebirds have hatched. There are now 4 nestlings, about 1 week old, at the north lookout nest box. The 5th egg did not hatch and was removed from the nest; sometimes the parents do this themselves. Hatching to fledging takes anywhere from 16-22 days. Both parents were seen bringing food to the nest.

Tree Swallows are finally in full swing. There are 9 Tree Swallow nests with 1-6 eggs each, for a total of 36 eggs so far. Tree Swallows typically lay 4-7 white eggs and incubate for 14-15 days once the clutch is complete. Unlike bluebirds, they have only 1 brood per season. Tree Swallows are very numerous along the lakeshore; the nest boxes are paired so that Tree Swallows can nest in one, leaving the other available to Eastern Bluebirds. In the photo, there is a swallow nest in the box on the left and a bluebird nest in the box on the right. Thanks to Mitch Nusbaum for helping with the monitoring.

May 10.
Not much to report today in terms of the nest boxes. The Eastern Bluebirds at the north lookout have not yet hatched, but should, any day now. Tree Swallows are still building nests and have not laid any eggs yet. There are partial nests, probably Tree Swallows, in 12 of the 18 boxes. A Tree Swallow nest is easily distinguished from nests of other species since they always line the nest cup with feathers. Nest boxes are paired so that Tree Swallows nesting in one box will defend the second box against other Tree Swallows, leaving it open for Eastern Bluebirds. This year, it looks like Tree Swallows may nest in both boxes of several pairs.

Today was a very busy day at Derby Hill – it was Onondaga Audubon’s 3rd Annual Bird Festival. Over 300 visitors were treated to live birds of prey demonstrations, guided nature walks, kids’ activities, vendors, raffles and a smoking barbeque. Birding highlights of the day included Prothonotary, Prairie, Orange-crowned and Hooded Warblers, and Red-headed Woodpecker. Thank you to Niles Brown, Karen C. and Carolyn S. for checking the nest boxes. Thanks to Donna Sponn and Mitchell Nusbaum for providing photos.

May 03, 2014
It continues to be cool and windy at Derby Hill. The good news is that the Eastern Bluebird nest at the north lookout now has a complete clutch of 5 eggs. Eastern Bluebirds generally lay 3-5 eggs. They start incubating once the clutch is complete; hatching occurs 12-14 days later. Expected hatching of this nest is around May 9-11.

Tree Swallows are defending boxes but still are not building nests. 17 out of 18 boxes are still empty; this is a very late start to the nesting season. The big excitement this trip was the Golden Eagle that flew over, only about 100 feet up, as we were checking boxes 6 and 7. Thank you to Mitchell Nusbaum for helping with this week’s monitoring and for taking the photos.

April 23, 2014
Cool, with NW winds as its been for the past several days. We have to remind ourselves that it is still early in the nesting season. Last year at this time, Tree Swallows were just starting to build their nests and there was one complete Eastern Bluebird nest, but no eggs. This year, no Tree Swallows have even started their nests yet. 17 out of 18 boxes are empty. But we do have 1 Eastern Bluebird nest in box 17 at the north lookout with 1 egg. We can only hope that this egg has not frozen.

The first Eastern Bluebird egg of the year.

The first Eastern Bluebird egg of the year.

Getting ready for the warmer weather, a ring of vaseline was placed around each of the poles to prevent ants from climbing up and making nests in the boxes. Some bar soap was rubbed on the inside of the roofs to discourage wasps from building their nests in the boxes.

A ring of Vaseline keeps ants from climbing up the pole.

A ring of Vaseline keeps ants from climbing up the pole.

April 10, 2014

The North American Bluebird Society advises “it is the responsibility of every nest box trail operator to ensure that no House Sparrows fledge from their boxes. It is better to have no nest box than to have one which fledges House Sparrows.” Why?? We think we are helping out bluebirds by providing nest boxes, but if we allow House Sparrows to fledge from these boxes, we are only contributing to the problem that caused the decline of the bluebirds in the first place. House Sparrows (really Old World Weaver Finches) were introduced into the US in the 1850s and have since become the most abundant songbird in North America. These prolific breeders start nesting in early spring and can produce 4 broods per year. They are cavity nesters and love bluebird boxes. The male House Sparrow is very aggressive – he forms a strong bond with his nest site – stronger than the bond he forms with his mate. He will even enter occupied nest boxes and kill all of the inhabitants, adults and nestlings, by pecking at their heads. Competition for nesting cavities is the main reason the Eastern Bluebird declined in NY State.

A male House Sparrow had been seen defending box 3A at the South Lookout. A VanErt trap was placed in the box and the offender was removed (see photos). House Sparrows are classified as pests and are not protected by Federal law as all of our native birds are.

No Tree Swallow or Eastern Bluebird nests have been started yet, but up to 10 Tree Swallows were seen fighting over a single nest box. One pair of Eastern Bluebirds was seen at the North Lookout. Thank you to Donna Sponn for helping with this week’s monitoring.

April 6, 2014
Nestbox season always starts with a clean-out of the boxes – making sure no rodents have moved in, making any necessary repairs, removing any residual nesting material and wasp nests. The clean-out, usually done in early March, happened late this year, due to the lingering cold weather. Our Hawk Counter, Steve Kolbe, observed the first of season (FOS) Tree Swallow on March 19, an arrival that swallow probably regretted. We did the clean-out on April 02; there was still significant ice on Lake Ontario and Sage Creek and snow around many of the nestboxes, but they are now all ready for the upcoming nesting season. There was a cold breeze off the lake ice that day, but as we worked, we were treated to an impressive flight of Turkey Vultures. Steve Kolbe, observing from the south lookout, counted 4,318 TVs, a new Derby Hill single day record. The Purple Martin house was also lowered and cleaned out, just in time for Steve’s observation of the FOS Purple Martin on April 05. There are at least 2 pairs of Eastern Bluebirds checking out boxes, one each at the north and south lookouts.

House Sparrows are an occasional problem at Derby Hill – the males are extremely aggressive and will enter occupied nestboxes and kill the occupants – both the nestlings and adults. House Sparrows may start nests in the DH boxes, but they are never allowed to hatch their eggs – the adults are trapped and removed. We placed monofilament on the front of select nestboxes to deter House Sparrows from entering – we’ll see how it works.
Thank you to Diana Green for helping with the clean-out. April 6, 2014

Birding at Derby Hill extends well beyond the spring raptor migration. DHBO maintains a trail of 18 bluebird boxes along Sage Creek Drive and at the north lookout. An open field with scattered trees or posts is ideal habitat for Eastern Bluebirds, a cavity nester. However, this close to Lake Ontario, the birds encounter extreme competitive pressure from Tree Swallows, another desirable cavity nester. The nest boxes are paired to help alleviate this pressure; the Tree Swallow will nest in one box of the pair and defend the second box from other Tree Swallows, leaving it vacant for Eastern Bluebirds to occupy.

Mouse over photos for captions

2013 Nesting Season

Nesting started late this year due to a bout of cold, rainy weather. The first Eastern Bluebird egg appeared on May 6 (compared to April 18 in 2012). Two successful nestings at the north lookout fledged 6 young. Tree Swallows laid 53 eggs and fledged 36 young. The spring weather was rough on these aerial insectivores.

The boxes are monitored weekly from March until the final fledging, usually in August. Visitors are encouraged to enjoy the cavity nesting birds, but please do not open the boxes. You may think you are being helpful by removing a House Sparrow nest, but displacing it may only cause the aggressive male to invade another nest box and remove eggs or kill nestlings and/or adults. It is better to leave the nest intact and let the monitor trap and remove the House Sparrow.

If you see a problem with any of these nest boxes, please report it. Better yet, come on up and join in on one of the weekly checks.

Photos and report by Diane Emord
Fall 2013