American Redstarts at the nest

Click here for HD version (a little less than HD resolution due to use of digital zoom)

This two minute video was recorded yesterday afternoon at one of our field sites in Frontenac Provincial Park. I stumbled across this site on a point count route that spans predominantly young deciduous forest from the Trail Centre to Big Salmon Lake. The site is an unusual “island” of mature hardwoods surrounded by rock barren meadows and successional forest. Arriving at my point count station in the interior of this mature woodlot, I knew it was going to be a busy ten-minute survey as a dizzying variety of breeding birds were wheeling about in all directions. Scarlet Tanager, Yellow-throated Vireo, Ovenbird, Least Flycatcher and American Redstarts were the most conspicuous species noted. The male redstarts were particularly memorable, singing from everywhere and seemingly at all times. In this region of the Frontenac, American Redstarts are most numerous in wet deciduous woodland with a dense shrub understory and this site has it in spades.

I spent a good 3-4 hours at this site on a previous visit in search of nests for the purposes of gathering data on breeding demographics of regionally “common” landbird species. The American Redstart nest featured above took over an hour to locate as I followed the male on a proverbial “wild goose chase” to an array of curious locations throughout the forest without any success until I finally tracked down a female carrying food to a nest about 7m high in the main fork of a young maple. Males can be polygynous, often holding court with multiple nests, mates and territories within the same breeding season. This might explain why the male seemed to be leading me around through such a large area.

I revisited the nest on the following day, a rather wet and dreary afternoon, with the intention of filming the adults feeding young at the nest. The chicks were just a few days from fledging and were therefore demanding a lot of attention in the form of proteins and household maintenance. The chicks were no doubt getting restless with the cramped conditions as no less than four of them, nearly full grown, were packed into this little cup nest. The chicks frequently stretched and flapped their wings in the time I was there. Both male and female were appropriately attentive, visiting the nest equally as much, about 5 visits/hour per adult individual. Both sexes carried away fecal sacs from the young and the male seemed to bring a substantially larger total mass of food to the nestlings. It was hard to identify the offerings from a distance but it seemed as though moth caterpillars were the food of choice. I also noted that the female would brood the young during brief periods of the heaviest precipitation. The pair were fascinating to watch, particularly the male, who was an amazingly adept hunter of green larvae hiding in the foliage.

the Nest Files – Common Nighthawk

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Common Nighthawk nest contents

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Although arguably the most studied nightjar in North America, the Common Nighthawk remains poorly known (Poulin et.al. 1996).

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Species Abstract
Common Nighthawk (Chordeiles minor)

Habitat=primarily nests in open habitats such as rock barrens (also gravel roofs in urban areas)
Area sensitive=?
Average clutch size=2
Nest building period=0 (no nest built)
Incubation period=19 days
Microhabitat=on ground on substrates of either rock, sand, gravel, lichens etc.
Egg colour=variable; creamy white to pale olive gray, heavily speckled with greys, browns and blacks.
Nest site selection=female
Incubation=primarily female
Parasitized by cowbirds=no
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This Common Nighthawk nest was first discovered at our Rock Ridge MAPS site on June 2, 2009. The female was inadvertently flushed from the nest when traversing one of the countless rocky flats at the site. Incidentally, a Whip-poor-will nest was also discovered on this day, less than 1km from the nighthawk nest. There won’t be many days of nest searching where that happens! Both of these species of the nightjar family have been much in the news of late because of their concurrent and precipitous decline in populations. Common Nighthawk was officially designated as a Species at Risk by COSEWIC in 2007 (Threatened) while Whip-poor-will was just recently recommended for listing in April of this year (Threatened). Nightjars are most active at dawn and dusk and are uniquely adapted to a food source of flying insects such as moths. It is suggested that the presence of a tapeta lucidum, a reflective structure of the choroid part of the eye, aids their vision during low light levels (Nicol and Arnott 1974). Relatively little is known about the breeding ecology and population dynamics of these two species, both of which commonly breed in the Frontenac Arch region of Ontario. Project Whip-poor-will will be starting up soon and will be designed to survey all nightjar populations in the FBS study area.

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The photo of the “nest” above is typical for Common Nighthawks where the eggs, usually two in a full clutch, are laid directly on the ground without any addition of materials or linings. They will sometime excavate a small scrape to contain the clutch but this activity seems to be determined by the habitat in which they choose to nest. The habitat for nesting nighthawks is quite variable, ranging from gravel rooftops in urban locations to a variety of open habitats adjacent to forests. They frequently inhabit rock barrens as in this particular case but will also nest in recently burned or clearcut forests as well as agricultural fields and grasslands throughout the continent.

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This short video clip was recorded of a defensive adult just after it was flushed off the nest. The Birds of North American account for the species describes defensive behaviour by both sexes as follows:

Male does not directly guard the nest (Dexter 1952) but may dive and boom over nest sites (Rust 1947); in addition, male may defend nest by wing-beating and hissing with mouth wide open (Dexter 1952). Female may use injury-feigning behaviour (fly away, then hiss at intruder) when flushed from eggs or young (Tomkins 1942).

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I spent no more than three minutes in the vicinity of the nest as I didn’t want to cause any excess amount of distress to the adult tending the eggs. I have a precise fix on its location and will be able to check on its progress at a distance from now on. The photos below provide a longer perspective on the nest site in terms of habitat. I have flushed several of both Common Nighthawk and Whip-poor-will in the area of our Rock Ridge MAPS station since the initial discovery of this nest but have not yet turned up any additional nest sites. The park has a large amount of suitable habitat for Common Nighthawks, perhaps about 1200 hectares worth, which suggests that the species might be common throughout rock barren areas. I will be traveling through much of the barrens starting next week for point count surveys and hope to encounter more of these fascinating birds.
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Nest site on rocky slope
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nesting habitat

Waterfront homes at Hemlock Lake

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Forest floor of regenerating coniferous forest

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Returned to the Hemlock Lake site yesterday to begin searching for mistnet locations and to get a better picture of the breeding bird community for our study. The visit was considerably more comfortable than my last when black flies were particularly menacing! This latest visit was cool with very few biting insects, which afforded me a great opportunity to get to know the site a bit better. What a difference a couple of weeks can make in the late spring! The emerging foliage was substantially further along, which created a much different looking landscape. Site visits in winter and early spring gave me a solid understanding of the scale, topography and structure of the site but I knew that it wouldn’t be possible to even consider positoning net locations until the canopy and understory had matured.

Upon entry to the site, I heard Eastern Towhee, Scarlet Tanager, Nashville Warbler and a concert of voice-battling Ovenbirds. Further along to where the forest turns from deciduous to mixed-coniferous, I encountered Black-and-white, Magnolia, Black-throated Blue and Blackburnian Warblers, all species we were expecting at the site. Also of interest were at least two territories of Winter Wren, one of the most vocally adept species on the planet! I was able to record a few seconds of one of our talented males holding territory in the site along with one of the unavoidable male Ovenbirds (click play to listen).

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Evidence of active nesting by many species included alarm calls, adults carrying nesting material and territorial disputes. I didn’t find a great number of nests but I did mark locations where a nest was suspected. I will have to return in a few days to a week to confirm presumed nest sites of Ovenbird, Black-and-white Warbler and Eastern Towhee among others.

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However, I did manage to find the nest of a Brown Creeper, which was discovered by patiently watching movements and behaviour of a pair in the standing dead timber at the edge of Hemlock Lake.  After sitting quietly for about 45 minutes, I was finally rewarded with the observation of an adult entering a tree with nesting material. The Brown Creeper places its nest almost exclusively in dead trees, between a loose flap of bark and the trunk. They build a hammock shaped nest of sticks and fibres, which is secured to the bark with insect-egg casings and spider silk. The nest will now be monitored with the goal of deriving a nest outcome. The information will be important to our demographic studies of breeding birds in the FBS study area and will be submitted to the Ontario Nest Records Scheme and Project Nestwatch for province-wide monitoring efforts. A closer view of the nest site is provided below.

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Brown Creeper nest site

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The most exciting discovery of the day led to this short video of a waterthrush carrying material to a nest in roots of an upturned tree along a clear moving stream. Northern Waterthrushes were quite vocal in the vicinity but this particular pair were all but silent except for some occassional contact calls between male and female. The calls were diagnostic of Louisiana Waterthrush but I will have to confirm identify of the nest owners at a later date. Northern Waterthrush are very similar in appearance with some subtle differences. It is best to distinguish the two by song, which are distinct. The Louisiana Waterthrush is a Species At Risk and a specialty of the Frontenac Arch region where an abundance of mature forest and clear moving streams provide suitable nesting habitat. The video is of less than ideal quality but one can clearly see an adult entering the roots about halfway up the screen to the left of the small tree trunk. The bird is more clearly seen at the end of the clip as it cryptically runs through the stream and out of the frame. Click here for HD version of this video clip.

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The Hemlock Lake MAPS station will begin operating in early June and continue with one visit per ten-day block through the final visit in late July. We will also be conducting a standardized nest monitoring study at this and the other two MAPS stations in the FBS study area. The site is turning out to be a terrific find and hopefully a long-term home for our research and monitoring programs.

Notable Species at Hemlock Lake (May 18,2009)

Great Blue Heron
Red-shouldered Hawk
Eastern Kingbird
Brown Creeper
Winter Wren
Wood Thrush
Swainson’s Thrush (migrant)
Northern Parula (migrant)
Nashville Warbler
Yellow Warbler
Chestnut-sided Warbler
Magnolia Warbler
Cerulean Warbler
Black-throated Blue Warbler
Black-throated Green Warbler
Blackburnian Warbler
Black-and-white Warbler
Ovenbird
Northern Waterthrush
Louisiana Waterthrush
Common Yellowthroat
Scarlet Tanager
Eastern Towhee
Field Sparrow
Song Sparrow
White-throated Sparrow
Rose-breasted Grosbeak
Baltimore Oriole