the Nest Files – Yellow-billed Cuckoo

Yellow-billed Cuckoo nest with eggs


Yellow-billed Cuckoo (Coccyzus americanus)


Nidiologicals – Peck and James (1987) and Hughes, J.M. (1999)

Habitat – Open woodland habitats with clearings and dense shrub cover.
Microhabitat – Nest concealed by foliage on outer branch or main fork of tree or shrub.
Spring arrival – Early to late May (Ontario)
Average nest height – 1m-2m (Ontario)
Nest builder – Male and female
Average # of broods/season – 1 (multiple broods may occur when food sources abundant)
Average egg laying date – 9 June-4 July (Ontario)
Average clutch size – 2-3 eggs
Incubation period – Average 9-11 days
Egg colour – Unmarked pale bluish green.
Incubation – Male and female
Brown-headed Cowbird host – Yes


Adult incubating

The cuckoo family (Cuculidae) is a diverse group of over sixty species that inhabit all continents of the globe except for Antarctica. The Yellow-billed Cuckoo, like its relatives, has an unusual and complex breeding system. Yellow-billeds are non-obligate brood parasites, meaning that they will tend to their own nests but also lay eggs in nests of other birds, especially when food sources are abundant. They will deposit eggs in other Yellow-billed Cuckoo nests (intraspecific parasitism) but also target Black-billed Cuckoo, Wood Thrush, Gray Catbird and American Robin (interspecific). These species lay eggs that are most similar in appearance to their own (unmarked blue to greenish), thus suggesting egg-mimicry is involved.

Male and female Yellow-billed Cuckoos build their nests within a few metres of the ground, usually in areas with a dense shrub layer. Nests are loosely constructed platforms composed of twigs and sparsely lined with dried leaves, plant tendrils and bark strips (Hughes 1999). The nest pictured above was discovered on May 25, 2010. The lining of this nest included fresh leaves while a sprig of Reindeer Lichen was added later. Both sexes incubate but the male brings new material to the nest when subbing in for the female. There is a vast list of fascinating factoids about Yellow-billed Cuckoo nests but I was particularly struck when I read that young are reared from egg to fledgling in just 17 days! This particular observation is astounding….

At age 6-7 d (26-29 g), feather sheaths burst open; nestling methodically preens off sheaths with bill; within 2 h nestling is fully feathered, but tail is still short (Hughes 1999).

This almost supernatural feather growth is colourfully described by Dr. A.H. Cordier in 1932 as follows:

The first picture was made at nine o’clock. . . . This shows the young by the unhatched egg; the horny, sheathed feathers were fully two inches long, making the bird look like a porcupine. About ten-thirty the sheaths began to burst, and with each split a fully formed feather was liberated. This process took place with such rapidity that it reminded me of the commotion in a corn popper or a rapidly blooming flower. All the while I was within three feet of the bird, and could see every new feather, as it blossomed, so to speak.

At three p.m., six hours after the first picture was taken, I made another photograph, showing this same bird in the full plumage of a Cuckoo, except the long tail.



I will be back to this nest very soon to check on its progress and also to sneak a peek at the young, which were described by Bendire in 1895:

The young when first hatched are repulsive, black, and greasy-looking creatures, nearly naked, and the sprouting quills only add to their general ugliness

This is the first Yellow-billed Cuckoo nest for our project but probably not the last. Both Yellow-billed and Black-billed Cuckoos are regular breeders throughout the Frontenac region. While much of the region is heavily forested with mature deciduous woods that are normally avoided by cuckoos, clearings created by wetlands, rock outcrops and ridgetops are abundant. Here in the arch, it is plausible that the Yellow-billed Cuckoo is yet another species benefiting from the rugged southern shield topography, low-intensity agricultural practice, shallow till and historical fires.

Cuckoo nest site

the Nest Files – Louisiana Waterthrush

Female LOWA entering nest


Louisiana Waterthrush (Seiurus moticilla)

Nidiologicals – Peck and James (1987) and Douglas Robinson (1995)

– Gravel bottomed streams flowing through mature deciduous or mixed forest. Also nests in wooded swamp habitats on occasion.
Microhabitat – Nest built in cavities of stream banks, upturned tree roots or fallen logs.
Spring arrival – mid to late April (Ontario)
Average nest height – 0m (always nests on the ground)
Nest builder – male and female
Average # of broods/season – 1 (multiple broods not reported)
Average egg laying date – May 3 – June 12 (New York)
Average clutch size – 5 eggs
Incubation period – average 13 days
Egg colour – Whitish, spotted or blotched with ruddy brown, usually concentrated at large end
Incubation – female
Brown-headed Cowbird host – yes


Nest building in progress


Another FBS first – a Lousiana Waterthrush nest! A territorial pair was first located on May 10th at this site but no further breeding evidence was obtained at that time. A followup visit on May 20th revealed both the male and female building this nest in the stream bank above a waterfall. So why the delay? It’s possible that an earlier nest was abandoned but it is more likely that nest construction was delayed after the pair bonded, which is typical according to previous studies (Robinson 1990). On May 20th the pair were observed entering the nest site, which at that time was bascially a mud bowl with a bulky leaf exterior.  The pathway of leaves visible here is a common feature of a Louisiana Waterthrush nest but is not always built. The above photo illustrates this ‘pathway’ constructed of dead leaves, which are noticeably damp and likely collected from the water. The wet leaves and the addition of mud are probably used for adhesion and support of the nest exterior and pathway.


Nest complete with eggs


There were four eggs in the nest this morning, which suggests that egg laying began by May 22nd at the latest (1 egg is deposited per day). There might be one more egg still to come as the average clutch size is five (Bent 1953). I watched the female incubate for about an hour before she slipped away for a break. The male was present, he sang on two occasions nearby and made short excursions to the waterfall but never approached the nest. With the female on break, I approached the nest to check its contents and snap a few quick photos.


Nest contents


The interior of the nest had transformed since my last visit. What was formerly an excavated mud bowl had become a neatly constructed cup nest lined with fine grasses, rootlets and animal hair.



This last photo shows the nest site context. This would be considered a fairly exposed nest site for the species. This spot wasn’t on my radar during my initial scan of the banks along the waterfall. There were several other sites that would have been more enclosed, shaded and difficult for non-avians to access. You can just barely see the stream bottom in the lower left corner. Luckily, relocating this nest has always been instantaneous thanks to the convenient tree root pointing to its location! Waterthrushes never fly directly to their nests, instead, they approach the nest by walking from a distance as great as 10m – very typical behaviour for ground nesters. This is nicely demonstrated by the following video of the female at the nest from this morning – whom I could have watched for hours if not for the oppressive heat today. If all goes well, the eggs will hatch in 8-10 days and I’ll be back to check on the family in early June.


Finally, here is a short video of an adult female LOWA at the nest from today’s visit. Just to avoid any confusion, I should mention that during the video you might hear a Northern Waterthrush singing nearby. The two waterthrush species “get along” very well and exhibit little or no interspecific aggression (Craig 1984). The video can be viewed at higher resolution here.

Natural nest sites of the Eastern Phoebe

Eastern Phoebe Nest


The Eastern Phoebe (Sayornis phoebe) is a common inhabitant of Southern Ontario. The 2nd edition of the Ontario Breeding Bird Atlas shows that peak abundance in the province aligns with the southern edge of the Canadian Shield. In these areas, the high forest coverage and availability of nest sites (e.g. cottages, bridges and other man-made structures) likely contribute to higher densities (Cadman 2007). It has been suggested that the species underwent a marked range expansion and population increase in unison with early development and human settlement, which greatly increased the availability of suitable nest sites (Weeks, H.P., Jr. 1994). Phoebes attach their nests directly to a vertically sloped surface, which provides overhead protection from the elements, in much the same manner as Barn Swallows (Hirundo rustica). Man-made structures such as bridges, culverts and eaves of buildings are just a few of many ‘unnatural’ features suitable for the species. What does this suggest for precolonial status of the Eastern Phoebe in Ontario? The nest pictured above was found last week and its location illustrates this question.


Nest site


The Eastern Phoebe has been a resident of Ontario’s woodlands since long before axe-wielding Europeans arrived. This particular nest was attached directly to a vertical rock wall below a cut in the rock. These rock formations occur throughout the FBS study area – in forest interiors, dry rock barrens and edges of lakes and ponds. It is plausible that the high numbers detected along the southern edge of the shield are also attributable to the proliferation of these naturally occurring nest sites. Click here for more info on nesting Eastern Phoebes in the Frontenac Arch.

the Nest Files – Field Sparrow

Adult Field Sparrow (D.Derbyshire)

Field Sparrow (Spizella pusilla)

Nidiologicals-Peck and James (1987) and M.Carey (1994)

Habitat=field, pastures and second growth forest edges and clearings
Microhabitat=nest built on or near ground; elevated in shrubs and tress later in breeding season.
Spring arrival=April
Average nest height=.2 to .5m
Nest builder=female
Nest building period=5-8 days in early part of season: 2-3 days in later part
Average # of broods/season= multiple (average of 2.9 in PA study).
Average Egg Date=26 May-21 June
Average clutch size=3-5
Incubation period=average 11-12 days
Egg colour=white or cream colour, heavily spotted on entire surface with denser markings at larger end
Fledgling stage=young leave nest 7-8 days after hatching
Parasitized by cowbirds=yes

Field Sparrow nest contents

The Field Sparrow, a close relative of the Chipping Sparrow (Spizella passerina), remains a common inhabitant of fields and various forms of scrub habitat in the eastern half of the United States, southern Ontario and Quebec. Rare north of the Southern Shield, the Field Sparrow has withdrawn from many areas in southern Ontario due to intensification of agricultural practices as well as the spread and maturation of forest cover in recent decades. They require open areas of dense low ground cover with some woody vegetation for nest support and song perches. It is likely that this species’ population reached its zenith in the 19th century when a low percentage of forest cover and low-intensity agriculture provided great expanses of suitable habitat. Here on the Frontenac Arch, the species remains abundant in rock barren habitats with its shallow till as well as abandoned farms. Forest fires would provide appropriate conditions for this species if not for current forest fire suppression practices.

The nest pictured above was discovered on a recent trip to one of our MAPS sites on crown land in the northern section of the FBS study area. Apart from farm fields, Field Sparrows are ubiquitously found in rock outcrops and in areas burned over in the mid-20th century. Eastern Towhee also occupy these areas and the two are almost always heard singing close together. This nest was actually the second Field Sparrow located at the site, the first of which failed for unknown reasons in early June. In both cases the nest was found elevated in a shrub, although this more recent example is considerably higher than the first, a typical response of the species to the increased growth of vegetation in late summer. The nest itself is similar to the nests of Chipping Sparrow, which are almost entirely constructed with grasses. One difference between the two is that Field Sparrows tend to use a lesser variety of grass types and less animal hair in the nest lining.

Field Sparrow nest site

The nest is located in a main fork within the crown of an as yet unidentified shrub/sapling. This plant would not not have been suitable for nesting in late spring/early summer as it would would have been exposed to predators in the absence of developed vegetation around it that has now provided dense cover.

Field Sparrow nest habitat

This shot of the nest site taken further back shows its position relative to our access trail. The habitat would be best described as a grassy clearing between dense deciduous forest and a large peat bog. To name a few, Yellow-throated Vireo, Scarlet Tanager and Yellow-billed Cuckoo sang from the forest edge throughout the summer, Swamp Sparrow, Common Yellowthroat and Wilson’s Snipe occupied the bog, while Eastern Towhee shared the sunny gap with Field and Song Sparrows.

Fledgling at Rock Ridge in early July

Fledgling and juvenile Field Sparrows have been encountered throughout the summer period across the study area. This area, with its countless rock outcrops and old fields, has been and continues to be an important region for Field Sparrows in Ontario. The retreat of the glaciers left extensive areas of bare rock and/or shallow vegetation resistant soils, providing open areas for Field Sparrows to prosper. It is plausible however that the suppression of fires, natural succession of fields and conversion to intensive agricultural methods will continue to reduce their numbers in Ontario and beyond.

Nest under construction: Red-eyed Vireo

CLICK HERE to watch this video in High Definition on Vimeo

The above video was captured over a period of four and a half days from June 27-July 1, 2009. A female Red-eyed Vireo began installing the foundation of a nest in a young maple about two meters above the ground on June 27. The process in its entirety was fascinating to observe as the footage revealed subtleties of technique and the use of various materials.

The Red-eyed Vireo (Vireo olivaceus) is one of the most common passerines of eastern forests in North America. A neotropical migrant, “Red-eyes” migrate to South America each autumn where they feed primarily on fruit. During the summer they are dedicated insectivores of mainly deciduous forest stands and fragments. The male Red-eyed Vireo is a vocal standout in the avian world as they hold the record for most songs per day of any bird species on the planet. In June and July the female Red-eyed Vireo builds a pensile or suspended cup nest from an outer fork of a branch-exclusively in deciduous tree species. The subject nest of this writing matches this description very closely. This particular nest was easily accessible for monitoring, providing a convenient window into the meticulous and masterful work of the nest building songbird.

I strongly recommend that you watch the HD version of the video to see the subtle movements and to appreciate the remarkable precision of the bill in manipulating nest material. The video clearly shows how important spiders and their webs are to nest construction for this and many other bird species. The female worked constantly during daylight hours over the course of four days. Review of the footage indicated that she visited the nest for periods of between three seconds to two minutes with an average of four minutes between trips. This rate would mean that just shy of 200 visits to the nest are made each day for a total of ~850 visits to complete a nest in four to five days!