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Monitoring Instructions
1) Terminolology
Clutch: Total eggs in nest
Brood: Group of birds in the nest
Broody: Word to explain why a female does not want to leave the clutch when the box is opened
Double Brood Box: Boxes that have fledged two broods
Triple Brood Box: Boxes that have fledged three broods
Fledged: The process of young leaving the nest
Fledglings: Young that have flown from the nest never to return
Fledgeout: Date that last young of the season leave the nest
Juveniles: Young that are living outside the nest; first stage of adulthood
Juvenile Assisted Feeding: Juveniles from the first brood who are assisting in feeding the 2nd or 3rd broods or the juveniles from the 2nd brood who are assisting feeding in the 3rd brood.
Nest Box Year: A nest box that has been monitored for one season
Nestling (= chick or young): Individual birds in the nest
2) Forms to use.
I prefer to use individual sheets for each nest box. I think that this form allows you to record data in much more detail than if you use the “Monitor’s Short Form” (20S). Whichever you chose to use, however, you should summarize the data on a Form 21 and send it to me by Sept. 1. When you use a Form 20, you are expected to determine the age of the young in the nest box to assure that you take caution as they age, in order to keep them from jumping out of the nest box (see below). If you monitor the nest boxes once every 6-8 days (1 week average), it is usually pretty easy to determine the age of the young.
The Form 21 has been dramatically altered for the 2008 season. We have eliminated spacing and nest box type in order to make the form more “user friendly”. Also, we are asking monitors to record data for both wrens and chickadees as they are important songbirds as well. All forms are available at www.braw.org.
3) Approaching & opening the nest box.
Monitor boxes once/week. Experience has shown that production of bluebirds improves if you visit one or more times/week. For example, if there is an extreme weather event and a nest gets wet, the eggs/birds can survive for only a few days. If you monitor the boxes only once every two weeks, you assure that the eggs/young will die under these circumstances. By visiting every week, you could build a dry nest and save the eggs/young (see below). Also, weekly monitoring helps you determine if the nest is active or not (see box below). Destroying inactive nests increases productivity.
It is essential, whenever possible, to get the hen to leave the nest prior to opening the nest box. Several times on the Audubon trail, hens have been injured as they attempted to leave the box when it was opened but could not use the exit hole. On at least one occasion, a monitor was so startled that he/she slammed the door shut, thinking that the young were escaping and crushed and killed the hen in the door of the box. Such accidents are rare but can be eliminated by using the approach given below.
As you approach the nest box, make a loud pishing or clapping noise from 10-20’ away. Pishing is commonly used by birdwatchers and involves making a shhhhhh sound with an explosive “p” sound preceding it (one continuous sound). If the hen does not flush from the nest, go to the back of the box and make loud tapping noises on it.
If the hen still doesn’t flush, step to the side of the box, away from the opening and open the box. The hen should flush from the nest. If she still does not flush, return to the back of the box and make both a pishing and tapping sound. If she is still so “broody” that she stays on the eggs (less than 5% of the time if the above protocol is followed), simply reach in and firmly pick her up from the nest and toss her in the air. She will chatter at you, but injury is not a problem with this technique (remember that smell is not a problem and this capture technique is used by bird banders on a regular basis). I have used this technique dozens of times without harm to the hen. This technique can also be used by other songbirds, but a hen swallow will grasp nesting material, so care should be taken when removing her, so you don’t remove her eggs.
By using these techniques, you should be able to get an accurate count of eggs and young, important data for BRAW.
4) Counting eggs & nestlings.
After you have flushed the hen from the nest, you are then ready to count the eggs and/or nestlings.
Counting eggs:
A complete clutch (= total) is 4-5 light blue eggs. In unusual cases, probably associated with exceptionally good habitat & feeding conditions, 6 eggs are laid. In all of the nests of eggs laid in the past 5 years of the Audubon trail, only one has had 7 eggs in it. All hatched and fledged, so such clutches are possible but ultra-rare. More commonly, representing 1-3% of all eggs laid on the Audubon Trail, are white eggs. None of our “white egg nests” ever have any blue eggs in them, so this condition seems to be a fixed genetic trait that does not vary over the lifetime of the individual, apparently a type of “egg albinism” (Gowaty and Plissner 1998).
When you look into the “hen-less” nest, pull back the cup edge and you will be able to see the eggs. If it is a Tree Swallow nest, you must part the feathers to find the eggs. The eggs of chickadees are covered when the hen leaves the nest, so carefully pull back the hair covering them to get a count. In some cases, it is best to “touch-count” the eggs. This technique allows you to count the eggs with minimal disturbance. Rarely, you will find a larger, brown-mottled egg in the nest that is likely to be that of a Brown-headed Cowbird. This bird is protected and the egg should be left in the nest to complete its natural cycle. To help prevent this parasitism, reduce the size of your box opening.
Incubation takes 13-14 days in bluebirds (Erhlich et al. 1988). However, data collected on the Audubon trail indicates that in cold weather, eggs may sit in the nest for up to 13 days before incubation begins, a very good reason to give the nest four weeks with a full clutch before destroying the nest.
Counting nestlings:
Healthy nestlings that are hungry will naturally “gape” when you open the nest box. If they are sleepy or recently fed, they usually can be enticed to gape by making a light pishing or kissing sound. If neither of those conditions allow you to get an accurate count of the nestlings, simply pick up one or two of them and spread out the others. I have used this technique hundreds of times without any harm to the young. And, remember, smell is not a problem for cavity nesting songbirds. Rearing chicks takes 15-21 days, depending on the time of year (spring is longer, summer shorter; Berger et al. 2001).
5) What should I do if nests remain incomplete, empty or with unhatched eggs?
All songbirds are protected by the Migratory Bird Treaty Act of 1918. The Act states: “unless and except as permitted by regulations…it shall be unlawful at any time, by any means or in any manner to pursue, hunt, take, capture, kill…possess, offer for sale, sell, purchase, ship, export, import…, transport or cause to be transported…any migratory bird, any part, nest, or eggs of any such bird...included in the terms of conventions between the United States and (Canada …the United Mexican States…and the…Government of Japan”.
BRAW absolutely supports this law. It is therefore illegal to destroy any nest, eggs or young of any songbird except in the following situations approved by Ms. Andrea Kirk, Permits Chief, Migratory Birds, USFWS Region 3, Ft. Snelling, MN 55111 on Dec. 27, 2006. Ms. Kirk has determined that nests and/or eggs of any songbird are inactive in the following situations and can therefore be destroyed:
- Partial Nests of any songbird that is monitored regularly: Week 1
If there is no more additional nest building in weeks 2,3 or 4, the nest can be removed in the 4th week. Timing restarts when there is any additional nest building- Complete Nests of any songbird that is monitored regularly: Week 1
If no eggs are laid in the nest in weeks 2,3 & 4, nest can be removed in the 4th week.- Complete clutch of eggs of any songbird that is monitored regularly: Week 1
If none hatch in weeks 2,3 or 4, touch eggs with back of fingers. If cold to touch, nests & eggs can be removed in the 4th week.
Five years of data collection from Audubon led to this ruling by Ms. Kirk of the USFWS. It is our experience that when empty, partial or complete nests or nests with unhatched eggs are left in the box, it “blocks” nesting attempts from individual hens that started the nest or from new hens. Although we do not know which “type of bluebird” is being blocked, our data indicate that removal of the nests using the procedure listed above, leads to a new nest being built and/or clutch of eggs laid, within one or two weeks in most boxes when this procedure is followed in the months of April through June.
On December 2, 2006, the BRAW Board voted 12 to 0 to establish the following policy:
“No bluebird monitor’s data will be accepted for seasonal reporting if they are known to destroy active songbird nests”.
Monitors are expected to follow the criteria for inactive nests approved by the USFWS on Dec. 27, 2006. If they do not and indicate that on their BRAW Form 21’s or in personal conversation with BRAW Board members, their data will not be accepted for consideration in BRAW reports and their names will be submitted by me as violators of federal law to the USFWS.
6) After the young have fledged, what do I do with the old nest?
I ask monitors on the Audubon trail to remove the nests from the boxes after the young have fledged. They are further asked to scrape off all feces on the sides of the boxes, but do not have to wash out the inside of the box. For those that are compelled to more thoroughly clean out the box, however, use only water and a towel (no soap; windex spray bottles work well).
I recommend removing the old nest from the area by placing it in a plastic sack and disposing of it in the trash at home. While insects such as blow flies are rarely a problem for songbirds in our experience, there is only one reason to leave the nest in place, that of leaving the jewel wasp, a parasite on blowflies, in place to parasitize blowflies in the next nest (Berger et al. 2001). Since it has been our experience that blowflies are not injurious to bluebird nestlings and that old nests block nesting attempts by other bluebirds, we still recommend removing the old nests except in the situation that follows: The longer one has a trail in place, the more common are second (and third) nestings. This means that new nests will sometimes be started prior to removing the old nest. In that case, the new nest can be built so high that it makes the bluebirds more vulnerable to predation because they are so close to the opening. If the nest is sturdy enough, it is possible to lift it off of the old nest and remove the old nest from under it. In other instances, it is so flimsy that it is best to leave the old nest underneath the new one. It is not worth the risk of disturbing nest building and the abandonment of the box by the hen.
7) Problems encountered while monitoring boxes
a) Nest boxes occupied by other bird species.
Swallows, wrens & chickadees are “good guys”, i.e., songbirds. They should be treated with respect as described above. The best technique to keep song birds other than bluebirds out of your boxes is to put them in habitat preferred by bluebirds, not other species.
Swallows prefer habitat with water over the drier, upland habitat preferred by bluebirds. Keeping boxes away from water (including marshland) will increase the chances of attracting bluebirds to them.
Wrens love short, dense, brushy vegetation with shading. Keep boxes 100’ away from such vegetation and usually you get only a dummy nest. Four weeks after nest building begins, you can legally destroy it (if it does not have eggs) and usually a bluebird or swallow will move in. It is best, however, to move the box another 50-100’ away from the dense vegetation, reducing the desirability of the site to male wrens.
Chickadees are the least likely to occupy a bluebird house. They prefer edges of woods and shaded nesting habitat. Keeping boxes 100+ feet away from such habitats will usually eliminate their nesting in your box. Sometimes they will occupy a box in the open, far away from woods. But it is rare that these nests are successful. There really is nothing you can to do to prevent these occupations. But three weeks after you experience a completed clutch without hatching, touch it to see if the eggs are being incubated (chickadees cover their eggs when they leave the nest, so carefully remove the hair covering them to “feel” the eggs). If they are cold to the touch, you can legally remove the eggs and nest.
House Sparrows are not native song birds and can legally be destroyed in any life stage: nest, eggs, young, adults. For five years, 27 different Audubon monitors have struggled with the drop in reproductive potential of bluebirds that sparrows cause. We continue to experiment, but so far, we have concluded that no nest box reduces sparrow occupancy. Davis & Roca (1995) and Jerry Schoen, BRAW Board member from Whitewater, claim that slot boxes help them control sparrows. It should be noted that the Troyer Slot box is the worst bluebird producer of all the major boxes, however (Table 6). What works best is to keep the boxes at least 200 yards away from livestock farms and out of suburban subdivisions where residents are feeding cracked corn and millet, as they are ideal foods for sparrows. That being said, we still have 10% of our boxes infested with sparrows.
The best way to permanently discourage sparrows is to let them lay their eggs and hatch their young. Then the young should be destroyed. Since neither landowners or monitors can normally “stomach” this approach, a secondary method is to let the sparrows lay their eggs (complete clutch is 5-7 eggs) and then destroy the nest. This approach usually discourages sparrows from further nesting. Still another technique is based on the fact that when the sparrow hen starts laying eggs the male will sometimes stay overnight with the hen in the box. It is possible then to capture and destroy both the hen and rooster. Sparrow “scarecrows or spooks” have proven ineffective in scaring off sparrows as they quickly adjust to them and return to the boxes. Finally, some people use a variety of sparrow traps to capture and destroy the adults. That is a permanent solution only if the male is captured as he will simply attract a new hen. Sparrow capture is so labor intensive that it is rarely used in trails of more than 25 boxes. I do not advise wasting your time trying to trap sparrows—simply move the boxes.
b) Wet nests.
Rarely do nests get wet in boxes. If they do, the most common reason is a “leaky box”. The first consideration, therefore, is to repair the box by replacing boards, tightening them or caulking leaks. Sometimes, under extraordinary conditions, winds will blow so strongly, that an otherwise “water-tight” box will “take on water” and produce a wet nest.
Songbird hens, including the bluebird, incubate their eggs at about 97F. A wet nest quickly drops the egg temperature below this level, causing them to arrest their development. Wet nests also cause abandonment of nests prior to egg laying. If there are young in the nest, especially less than a week old, they will quickly die of hypothermia from a wet nest, especially in cold weather.
The bottom line is, replace all wet nests with dry material. It is best to begin the season with a small sack of dried vegetation, good enough for making up to 6 nests. All too often, when you experience finding a wet nest, all other vegetation around the box is wet. “Plan ahead” is a good policy when it comes to wet nests. Once the hen completes a nest, she will tolerate any kind of cup-shaped vegetation that might be available to make a “humanly-constructed” nest. Preferred materials, however, include white-pine needles and any dead, short-leaved grasses. Soft grasses are better than hard, brittle ones.
All the monitor has to do is form a cup-shaped nest approximating the dimensions of the nest in the box. Remove the eggs or chicks from the wet nest and place them in the dry nest. Put the dry nest with eggs or chicks, back into the box and pat it down a bit to approximate the size & shape of the previous nest. Do not worry about this part of the process, however, as the hen will quickly arrange the new nest to her liking (and thank you as a bonus). Audubon monitors have done this procedure dozens of times and it is 100% successful if the nest can be replaced soon after it gets wet.
c) Starving chicks in the box.
In 2005 & 2006 a total of 42 nestlings were found starving in the boxes on the Audubon Trail. 37 of them were saved by following the procedures given below:
The first step is to identify starving chicks. If there is a dead chick in the nest already, that is usually a good sign that other chicks in the nest are stressed as well. It is more likely, however, that you will discover starving chicks by finding them largely unresponsive to your typical pishing/kissing noises. In addition, if no adults are seen around the nest box, it is likely that one or both parents are dead or have abandoned the chicks.
If it is cold weather, wrap the young in tissue or toweling that will keep them warm. If it is hot weather, heat will be their enemy, so keep them as cool as possible.
You should locate a nest with chicks in it that are somewhat younger than the age of the chicks that are starving. This strategy is important because the starving young are retarded in their physical development and after being adopted by the new parents will grow at about the same rate as the younger chicks.
Often, however, trails are so small that not many choices are available to use for adoptive nests. I have successfully fostered chicks into nests in which the occupant chicks were 6 days older than the adopted chick(s). This places a hardship on the parents, however, as they have to cope with juveniles outside the box and a chick(s) inside the box. But the technique will still work.
Another rule of thumb is to put no more chicks into the adoptive nest than will total 5 or 6 (6 only if absolutely necessary. Two healthy adult birds can raise 5 chicks in most cases, but coping with 6 is stressful and can lead to the loss of the adoptive chick.
d) Critters invading the box.
i. Blackflies.
Blackflies are the most dangerous insect for cavity nesting songbirds. They seem to be most common in the southern and western part of the state, particularly around slow moving rivers. Gary Gaard, BRAW member from Dane County has discovered that they are less likely to enter boxes with closed vents (www.braw.org /BRAW articles/Gaard).
So if you are losing entire broods, healthy one week and a dead, amorphous mass the next, it could well be blackflies. Check around the wings and abdomens for small bite marks, the sure signs of black fly infestation. The best thing to do in the case of chick loss to black flies is to close the vents until the end of the season.
ii. Blowflies.
In the 5 years of the Audubon study, 1262 nest boxes have been monitored, representing 1262 nest box years. During this time, no known deaths have occurred to nestlings because of blowflies. We think they are a non-issue, at least in central WI. During the months of June-August, we find them in up to 50% of our nests, often with dozens of maggots.
Blowfly larvae are gray-brown and about ½”” long and are usually not very active when you find them in the nests. It is true that blowflies are ectoparasites on nestlings, attaching to the abdomens for nourishment. Typically, these “feedings” occur at night and the larvae return to the safety of the nest during the day.
My advice is to ignore the blowfly larvae because they are harmless to the songbird young. But you if you think they are a problem, you can get rid of them by removing the infested nest and replacing it with an artificial nest that you construct as per the instructions above.
iii. Ants.
Ants are rarely a problem in nest boxes in central WI, although they have “been known to attack, kill, and devour newly hatched nestlings on occasion. They may even attack and kill the young birds by entering the eggs as soon as the shells are cracked in the hatching process. (Zeleny 1976).
Pyrethrin sprays are safest for spraying ants in nests but they are short acting. On the Audubon trail we Use “Bonide bug beater yard & garden insect control granules” (Bonide Products, Inc., Oriskany, NY). By putting these granules on the nesting platform underneath the nest, they do not come into contact with nestling or adult songbirds. They are very effective and last much longer than pyrethrin sprays. We have noticed no harmful effects from these granules.
iv. Mites
In our 1,262 nest box years, we have recorded no known fatalities from mites. In fact, it is rare that they occur in numbers large enough to be detectable by humans. But sometimes, they overrun a nest and must be dealt with when removing the old nest. It is best to use gloves as they are “creepy crawlers” of the worst kind. They do not harm humans (and apparently the birds in the box), but they are un- comfortable if they get on your skin. Just rub them off and try to “dust out” the box as best you can so the next brood will not start with a bad infestation.
v. Wasps
Rarely, wasps attach inside the nest box but more commonly they attach underneath the nest box. It is always possible to get stung by them, so caution should be used when removing the nest. To prevent their further attachment to the same site, spread vasoline or bar soap over the place the nest stalk attached to the box.
e) Climatic Effects.
In northern latitudes, cold has proven to be the most limiting factor during the reproductive season, much more so than heat (as reported by bluebird monitors across the state).
In 2006, for example, an intense low pressure system dominated the weather throughout Wisconsin during the week of May 11 & 12. For 48 hours on those two days, cold, wind-driven rain fell and caused hens to abandon eggs and/or chicks in order to survive themselves.
In the one week of May 11-12, a total of 286 eggs & chicks were lost on the Audubon trail. That 2-day number represented 26% of the total loss of 1098 eggs & chicks for the entire season and exceeded the total loss of eggs & chicks in the two hot months of July & August. This is an extreme example of the underlying principle that the majority of egg & chick loss occurs in the colder months of April & May.
The principle of “cold is bad for reproductive success”, is a major reason that BRAW recommends to close vents until June 1 (leave closed until July 1 in areas vulnerable to black fly infestation).
So Why Monitor Bluebird Boxes?
At the start of this “monitor’s guide”, I indicated that a major reason for developing bluebird trails is to preserve bluebirds and other cavity nesters. But bluebird trails are more than just for conservation of the creatures of creation. It is for us. It is vital for us to be associated with a conservation project.
Few persons in the world have the chance to experience the wonder and mystery of following the develop- ment of a wild creature. But nest box monitors do. This is a sacred experience that should be shared with as many people as possible.
It is likely that in this modern age of technological marvels, fewer and fewer children have the chance to “experience nature”. Take adults & especially children with you on your monitoring trips. Explain to them the wonders that you see each time you go out on your trail. Good luck finding, raising and fledging “the blues”.
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