Category Archives: Birds

Tree Swallows at Opinicon

Post by Art Goldsmith

(unless otherwise credited, photos by Art Goldsmith, tree swallow photos by P-G Bentz )

Thanks to the following people for assisting with advice, content and research: Prof. Fran Bonier, Ph.D. candidate Catherine Dale, and Prof. Raleigh Robertson.

The Bird, The Research, The Sordid Truth: Do Tree Swallows Murder Nestlings and Cheat on Their Partners?

Yes, the daily tabloid newspapers are rife with sleazy debauchery, and so is this Blog, at least when it comes to Tree Swallows (Tachycineta bicolor) referred to by the abbreviation TRES. The story of the Tree Swallows at QUBS is integral to the development of the station by two remarkable leaders, Prof. Raleigh Robertson, who was Director of QUBS for 33 years, and Frank Phelan, who has managed the Station for 40 years, and who will be retiring at the end of 2015. Their story, which is also the saga of a small research station on the shores of Lake Opinicon morphing into a primary and pre-eminent 8500-acre regional research, education and conservation centre, deserves a separate post.

Back in 1974, Prof. Robertson had been continuing his studies of Red-winged Blackbirds (RWBL ) when, and this story is worthy of a movie script, the potential acquisition of 1000 acres (Hughson Farm) at the south end of Lake Opinicon prompted some thought about other studies. Coincidentally, Geoff Holroyd came to Queen’s from Long Point Bird Observatory (LPBO) with a number of nest boxes. As with so many human advances, the interplay of events prompted invention and the TRES studies commenced. Having already conducted RWBL habitat selection studies, Prof. Robertson decided to use the newly acquired nest boxes to study habitat selection of TRES on the Hughson property (in the illustration below by Dr. Raleigh Robertson, the Hughson tract is shown in green). The original pre-1974 QUBS is shown in light blue. The additional tracts, up to the year 2007, are shown in various other colours. The illustration shows several Tree Swallow photos, including a natural tree cavity nest and a nest box.

Slide provided by Prof. Raleigh Robertson
Slide provided by Prof. Raleigh Robertson

The following four paragraphs are paraphrased from personal communications with Prof. Bonier:

North American Breeding Bird Survey (BBS) data since the mid 1980s shows declining populations of aerial insectivorous birds, particularly in northeastern North America (Shutler et al).

Update: Prof. Bonier has informed me (November 9, 2015) that a new study (science is always progressing!) indicates this geographic pattern for aerial insectivores is not as strong as the Shutler team thought. The exception is Tree Swallows, which are, indeed, increasing or stable outside of northeastern North America.

Tree Swallows are aerial insectivores, and therefore, the network of TRES nest boxes afforded an opportunity to study the population at QUBS. Several hypotheses have been put forward regarding the drops in populations. I have spoken to people (at QUBS and elsewhere) who believe greater survival of parasites may be responsible. This is one of the disease parameters that Prof. Bonier mentioned in her communication with me. Prof. Bonier has determined that malaria parasites have not increased in Tree Swallows over time. Other parasites may have an effect on populations. Other climate-linked hypotheses include phenological changes, especially earlier life cycling of important insect prey.

Prof. Bonier inherited the QUBS TRES boxes from Prof. Robertson, and she ran studies on them since 2007. She compiled all of the demographic data on the population (from 1975 to present) and has used the data to test a couple of hypotheses about proximate causes of the population’s decline. The story seems to be this: the population has been declining fairly rapidly and steadily since ~1990, when it was at its peak (with every single box occupied by a breeding pair). The all time low of 23% box occupancy was last year (2014). That’s an even lower occupancy than 1975 when Prof. Robertson first put up about 70 boxes to start the population (and occupancy was 26%). This year, 2015, occupancy rebounded a bit to 35%. From this amazing data set, we can show that on average, per nest fledging success has not changed over time, nor have adult return rates (a proxy of adult survival). However, first-time breeders are coming into the population at a lower rate. This is true for immigrants into the population as well as resident nestlings returning. At its peak, 10% of all nestlings that hatched in boxes at QUBS in a given year returned later as breeders. Now there are rarely any coming back. So this would suggest that something is happening to dispersal and/or survival during the first year of life, between hatching and first breeding. Prof. Bonier and her colleagues are pursuing analyses on climate and disease to explore possible causes of this change, which might help us differentiate the two.

The population at QUBS started its decline in 1990’s. Significant climate change has been documented in our region from 1980 onward. That causes me to lean to that predominant factor as a major contributor to the drop in our local populations. The research also tells us that TRES are also expanding their range in the southeast, at the same time as return rates drop here. This raises even more questions. Climate change tends to be more pronounced from south to north. An expansion of the range to the south is interesting since it causes me to wonder why these birds have not occupied the southeast in the past, and what has changed to cause them to expand in the south now? More nesting opportunities? Less competition?

For detailed life history information read the Tree Swallow species account at the Cornell Lab of Ornithology.

The conclusion of the Shutler (citation follows at the end of the TRES portion of this blog post) paper to which Prof. Bonier and Prof. Robertson contributed:

“The broad geographic patterns are consistent with a hypothesis of widespread changes in climate on wintering, migratory, or breeding areas that in turn may differentially affect populations of aerial insects, but other explanations are possible. It is also unclear whether these changes in occupancy rates reflect an increase or decrease in overall populations of Tree Swallows. Regardless, important conservation steps will be to unravel causes of changing populations of aerial insectivores in North America.”

Prof. Bonier also has links to the Virginia Tech people doing research in that part of the U.S. (probable increasing population southward). They have found that TRES displace Bluebirds at nest boxes. Prof. Bonier wrote:

“TRES in the northeast of North America are declining, whereas other locations are stable or increasing. We are studying TRES with collaborators Ignacio Moore (Virginia Tech) and Mark Stanback at Davidson College in North Carolina, where they have been displacing eastern bluebirds from his study site. TRES never used to breed there, and now are abundant and occupy almost all of his nest boxes. Ignacio put up nest boxes near the Virginia Tech campus last fall, and already has higher box occupancy than we have at QUBS. So in the southeast, it does seem that TRES are increasing and also expanding southward.”

For more about Prof. Bonier’s current research, see the news article posted on the Virginia Tech web site.

Thanks to Prof. Robertson’s long term research, we have learned a lot about the mating and nesting behaviour of Tree Swallows, and their selection of nesting sites.

TRES_male_on_boxLeft, a male Tree Swallow stands guard while a first-year breeding female brings nesting material to one of the nest boxes at QUBS. Professor Robertson studied the unusual “late onset of adult plumage” in Tree Swallow females. Among the many interesting traits of these birds, the delayed adult female plumage characteristic is very unusual in the bird world. Delayed adult plumage is common among adult males of many bird species. Male TRES are fully iridescent blue by their second year. Females only attain such “blueness” later in their 2nd year. Why would this be?

It is this kind of observation and hypothesis development that characterizes good science.

So using a variety of methods, Prof. Robertson and colleagues went about testing their hypotheses regarding the late plumage onset of TRES females. And this is what they found.

When a one-year-old female TRES arrives at a nest box inhabited by a nesting pair, the resident male is less aggressive towards a one-year-old female than toward older intruders. The female is equally aggressive toward all females. Isn’t THAT special? It turns out these young, less brightly feathered females are, indeed, LOOKING for breeding opportunities, as they visit many nests to seek out a tryst with a resident male. And many males respond quite positively. Note that these visits last only a few seconds. Birds are quicker than people! Another interesting result: older females are much more successful at raising young early in the season. Later in the season, the younger females, which were experimenting at a lot of different nest boxes earlier are, later in the season, breeding much more than their older counterparts AND they are being just as successful.

Nest box constructed and donated by Opeongo High School. These have been placed along Queen’s University Rd. for display purposes.

This is a later vintage QUBS nest box, with the effective anti-rodent device pictured below the box. Its location beside the road into the QUBS buildings is not particularly suitable for TRES, which prefer the nest boxes in open hay fields, but are occasionally occupied by House Wrens and Black-capped Chickadees. Raccoon, snakes, and squirrels are among the most prevalent and successful predators of songbird nests. Next time you are thinking about how cute squirrels are, recall this fact! Larger snakes are the only predator capable of circumventing these collars.

vigilant_TRESA vigilant adult Tree Swallow is pictured above. After reading through this blog, I expect people will wonder more about what goes on in birds’ brains as they look at us. Perhaps some of these surprising revelations will prompt some to wonder all the more.

Sex and Infanticide: Tree Swallows, the Sordid Side

TRES_flyingPeople look on small songbirds as benign, benevolent and harmless. Evidence abounds for these traits. Although, in my opinion, the following evidence doesn’t change an overall positive image, it does give one pause. Your blogger has observed the sweetest of birds, the Black-capped Chickadee joyfully feeding at a deer carcass in mid winter. During a winter snowshoe sojourn, a Red-breasted Nuthatch flew onto my shoulder demanding FOOD, and gave me a most malevolent look when the lack of bird seed was apparent. And, given an opportunity, male Tree Swallows will massacre a previous male’s offspring in order to start its own brood.

Prof. Robertson studied this behaviour by removing males from nest boxes. Sexually selected infanticide is quite rare in birds. It is more common in mammals. So seeing this behaviour in TRES is of great interest to ornithologists. During incubation, with eggs in the nest, Prof. Robertson removed 17 males. In three cases, the males were not replaced. However, a large proportion of the males, 11, killed the nestlings when they hatched. Three others adopted the newly hatched nestlings.

If the new male is introduced during egg-laying, (Robertson removed 11 in this instance), 4 were not replaced and all of the other 7 replacement males did adopt the eggs and nestlings. Finally, the same experiment was completed during the nestling stage (15 males removed), and five of the fifteen killed the nestlings. Of these 5, only 1 re-nested with the widowed female; two re-nested with a new female and two did not re-nest. So why would so many kill the newly hatched nestlings? Researchers studying with Prof. Robertson found that the behaviour is adaptive. That is, there is an advantage to those males who kill the previous male’s offspring, as they disproportionately pass on their genes. This raises more questions, which future Queen’s students may answer using the unequaled resources at QUBS.

copulation_TRES1Above and below: copulating Tree Swallows. You don’t have much time to see this happen, as the usual copulation event lasts just a few seconds!

TRES_post_coitusBelow, the happy couple look innocently toward the camera. The question is, is that the resident female for this nest box? It may not be … read on.

TRES_innocent_looksWhat about the secret mating among TRES, that is, one of a mated pair sneaking off to pair with another TRES, and, as already discussed, the young females with their juvenile plumage, visiting males in nest boxes? The facts are surprising. The euphemistic ornithological expression is “extra-pair” mating and paternity. Based on observations, it appeared that TRES are models of social monogamy. Hold on! That is another fun feature of good science. What appears to be happening based on observation may conflict with the facts. A good detective follows the evidence. And the evidence is:

80% of nests contain some extra-pair offspring!
50% of all nestlings are sired by extra-pair males!

So seeing ISN’T believing. There is a lot of “visiting” going on, and it happens quickly and surreptitiously…so much so that trained observers don’t see it.

Seeing this result from a MALE perspective, the benefits are obvious: the male has more offspring spread over more nests, making survival more likely (literally male Tree Swallows have their eggs in more than one basket!).

What does the female get? She still has her nestlings all in one basket, and she still gets the same contribution to care by one male. Once again, the facts are both interesting and unexpected. It is the FEMALES that control extra-pair copulation. They are the ones who stray.

After some very intensive study and some very difficult analysis, research has concluded that the female, as well as the overall population, does receive an important benefit. These pairings result in better genetic compatibility, not in overall better genes. Genetic compatibility (i.e. simply the genes from each partner vary in how well they work together. Some genes pair up for greater benefits. The more pairings, the greater likelihood of compatible pairings) is an adaptive advantage.

How Tree Swallows Select Nest Location

In the photo series below, Tree Swallows are photographed at various natural tree cavity nest locations. As you would expect, forestry, farming and other land uses have limited and reduced the numbers of tree swallow nests. Natural cavities produced by wood peckers, disease or physical damage must be, ideally, close to water or open fields, so Tree Swallows have a ready source of food, such as insects emerging from water and fields. Artificial boxes do help alleviate this limiting factor.

Tree Swallows, outside of nesting season, are very social. They form large flocks for migration and over-wintering. The author has seen flocks of thousands over bays in Florida. That changes when they nest. They like some space between nests.

On average, artificial nest boxes are larger, roomier and safer than natural cavities. However, whether a natural cavity or nest box is selected, TRES like their nests to be spaced an average of 28 meters apart. Researchers at QUBS determined this optimal distance through a spiral alignment of boxes in a field.. The second birds to arrive to nest usually choose the most distant nest box form the first pair. After a few weeks, nest selection becomes more random, but males do defend their nests aggressively from other TRES males. QUBS nest boxes are now set up in a grid pattern in optimum habitats. This territorial behaviour differentiates Tree Swallow from other swallow species which are more colonial.

Current research on TRES is focused on applied ecology, especially ecotoxicology. Professor Fran Bonier, who contributed greatly to this blog, is studying how Tree Swallows adapt to environmental stresses, for example through endocrinology field studies. See her current Queen’s web page for more information.

  • Citations:
    Spatiotemporal Patterns in Nest Box Occupancy by Tree Swallows Across North America, Avian Conservation and Ecology 7(1): 3., D. Shutler et al, 2012.
  • Field Ornithology-Agent for Science, Education and Conservation, presentation to the Society of Canadian Ornithologists Annual Meeting, Dr. Raleigh Robertson, September, 2007.
  • Personal Communication, Dr. Frances Bonier
  • Personal Communication, Dr. Raleigh Robertson
  • Personal Communication, Catherine Dale

I want to leave you with a few images of the Queen’s University Biological Station:

(Photo by Jan Tripp)
(Photo by Jan Tripp)

Your blogger, Art Goldsmith, with Professor Raleigh Robertson, left. The new Jack Hambleton Library (officially opened in June) is at the upper right. The building also now houses the Fowler Herbarium in state-of-the-art facilities. We believe this is the only field station with on-site access to such a large herbarium collection. Below, the large central QUBS building, with a cafeteria, labs, offices and a large seminar room, is named for Professor Robertson.

RJR_Centre_dining_hallPhotos, books, and artifacts belonging to Jack Hambleton are displayed in the new library named for Hambleton.

Next time, we will start our series of field course blogs. This includes the courses on Insects, Aquatic Ecology (a different course from the China-Canada Course), and Fabulous Fall Fungi. See you then.

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A brief digression on parrots.

by Stephen C. Lougheed

The parrots comprise a large order (Psittaciformes) of birds with a mainly pantropical distribution, although some species do inhabit temperate regions in the Southern Hemisphere as well (e.g. the burrowing parrot, Cyanoliseus patagonus, of southern South America). Number of species reported varies but generally is on the order of 340 to 370 distributed across between 78 and 86 genera (Rowley and Collar 1997). Characteristics of parrots will be familiar to most: robust, curved bill, strong legs with zygodactylous feet (two toes forward, two toes facing backward). Many are brightly-coloured although some, like the sulfur-crested cockatoo (Cacatua galerita) are mostly white, while others, like the flightless Kakapo (Strigops habroptila) of New Zealand, have muted and cryptic plumage patterns to avoid predators.

OLYMPUS DIGITAL CAMERA
Northern rosella taken in Litchfield National Park. Click on thumbnail for larger image.

In my still unfolding peregrinations in Australia I have already seen 10 species of parrot including this lovely northern rosella (photo by Cam Hudson – see his blog  – from some distance – but still showing some of the vibrant colours).

My list thus far includes:

  • Red tailed black-cockatoo, Calyptorhynchus banksii

    OLYMPUS DIGITAL CAMERA
    Gallah taken just outside Nitmiluk National Park. Click on thumbnail for larger image.
  • Yellow tailed black-cockatoo, Calyptorhynchus funereus
  • Gallah, Eolophus roseicapilla
  • Little corella, Cacatua sanguinea
  • Sulfur-crested cockatoo, Cacatua galerita
  • Rainbow lorikeet, Trichoglossus haematodus
  • Red-shoulder parrot, Diopsittaca nobilis
  • Eastern rosella, Platycercus eximius (see photo)
  • Hooded parrot, Psephotus dissimilis
  • Northern rosella, Platycercus venustus

Carolina_parakeet_JJ_AudubonUnfortunately, at least 80 species of parrot are classified as vulnerable or endangered (IUCN 2013) due to a mixture of habitat loss, collection for the pet trade, and persecution because some are considered agricultural pests (Collar 2007) with some already extinct. Indeed, the only psittacid of Eastern North America went extinct in the early 20th Century. The Carolina parakeet (Cacatua galerita) once ranged from southern New York, south to the Gulf of Mexico and as far west as Nebraska (Snyder 2004). The Carolina parakeet was a lovely species, with bright yellow head, orange face, green body and pale bill (see John James Audubon’s rendering here). One can imagine that, before European settlement (and ensuing loss of the Eastern deciduous forest, persecution because it foraged on orchards, and hunting for the millinery trade – nothing like a stuffed parakeet on your hat I guess – see Saikku, 1990), very occasionally one might even have seen a northern vagrant parakeet in Canada.

References

  1. Collar, N.J. 2007. Globally threatened parrots: criteria, characteristics and cures. International Zoo Yearbook 37: 21–35.
  2. IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 22 January 2014.
  3. Rowley, I. and N.J. Collar. 1997. Order PSITTACIFORMES. In Handbook of the Birds of the World – Volume 4. Sandgrouse to Cuckoos. (J. del Hoyo, A. Elliott, J. Sargatal eds.) Lynx Edicions
  4. Saikku, M. 1990. The extinction of the Carolina parakeet. Environmental History Review 14: 1-18.
  5. Snyder, N.F.R. 2004. The Carolina Parakeet: Glimpses of a Vanished Bird Princeton University Press. Princeton, NJ.

Rise of the Red-bellied Woodpecker

Posted by Mark Andrew Conboy

Red-bellied woodpecker
Male Red-bellied Woodpecker (Melanerpes carolinus). Source KenThomas.us

Numerous species of birds in Ontario have expanded their ranges further north in during the past century. For example, the Turkey Vulture (Cathartes aura) has dramatically extended its range throughout Southern Ontario beginning in the early 1900’s, when it was rare in most of the province but is today a common species north into parts of Central Ontario. Mourning Dove (Zenaida macroura), Northern Cardinal (Cardinalis cardinalis), Orchard Oriole (Icterus spurius) and perhaps even Cerulean Warbler (Dendroica cerulea) have all undergone similar range expansions (Cadman et al 2007). In recent decades this pattern has continued with the Red-bellied Woodpecker (Melanerpes carolinus), which is now being sighted with increasing frequency in Eastern Ontario.

Red-bellied Woodpeckers have always been considered fairly rare at QUBS so their apparent sudden increase in the area is of considerable interest. I have been recording occurrences of this species on our properties since 2008. I summarize those observations below:

2008
1 on the Moores Tract
2 at the southeast corner of Hughson Tract (copulation reported by Frank Phelan)
1 at Lindsay Lake Road

2009
1 at the Southeast corner of Hughson Tract
1 on Lindsay Lake Road

2010
2 in Silver Maple Swamp

2011 (to date)
1 north of Warner Lake
1 at QUBS Point (visited bird feeders at Ironwood Cottage)
1 on Old Bedford Road
1 on Lindsay Lake Road
2 at the Dowsley Ponds

Additional sightings from the QUBS area reported on eBird (http://ebird.org/content/ebird/) by other observers are: 1 at “QUBS” in 2008 (Martin Piorkowski); 1 at Bedford Mills in 2010 (Peter Blancher); 1 at the cemetery on Opinicon Road (Patrick Blake) and 1 in Elgin (North Leeds Birders), both in 2011. So far the only breeding evidence we have is a pair observed copulating on the Hughson Tract in 2008 (Phelan, personal communication). Observations of Red-bellied Woodpeckers from other parts of Eastern Ontario include occasional eBird reports from Charleston Lake (to the south of QUBS) are starting in 2005 and the Ottawa area (to the north) starting in 2009.

Why Red-bellied Woodpeckers are now expanding into Eastern Ontario with success at this time is unclear. Possible explanations include changing climate contributing to increased winter survival; additional foraging opportunities resulting from bird feeders; and maturation of second-growth forests providing appropriate breeding habitat. The most recent edition of the Atlas of the Breeding Birds of Ontario 2001-2005 showed that 15 species expanded their range edge northward in Ontario in the 20 years since the first edition of the atlas. The northward expansion of most of these species may be attributable to any or all of the aforementioned hypotheses for the Red-bellied Woodpecker.

20 Years of Red-shouldered Hawk Surveys on Opinicon Road

Posted by Mark Andrew Conboy

Any day now the skies over Eastern Ontario will begin to ring with the calls of Red-shouldered Hawks (Buteo lineaus). This vocal hawk is one of the most commonly encountered raptors on the Frontenac Arch. It’s also one of the few forest raptors that have been subject to long term monitoring in Eastern Ontario. Beginning in 1991 the Red-shouldered Hawk and Spring Woodpecker Survey has been conducted each year along Opinicon Road in an effort to keep track of Red-shouldered Hawk numbers. In this post I summarize the results of 20 years of counting Red-shouldered Hawks along Opinicon Road. The counts were completed by Ron Weir and others. Thanks to Ron for providing me with the survey data.

The results of the Red-shouldered Hawk surveys show that there has been a significant increase in Red-shouldered Hawk numbers since 1991 (P=0.0013). The lowest count was 5 birds in 1992. The highest count was 27 birds in 2003. The mean count is 17.05 birds. Red-shouldered Hawk numbers across their Ontario range appear to be steady or increasing and the data from Opinicon Road matches this trend.

QUBS is situated in what is currently the heart Red-shouldered Hawk abundance in the province (Cadman et al 2007). The largely intact forests that cover our part of the Frontenac Arch provide habitat for these sylvan raptors and are likely the reason for the high numbers recorded here. Red-shouldered Hawks may have been far more abundant than they are today all across Ontario prior to the conversion of forests to farmlands (Weir 2008). The species continued to decline in the mid 1900’s. In 1983 the Red-shouldered Hawk was designated a species of concern in Canada, due to the large declines in populations associated with forest clearing. In 2006 it was reclassified as not at risk. Today the most commonly observed hawk in the region is the Red-tailed Hawk (B. jamaicensis). It prefers large tracts of farmland or other open terrain. It has probably replaced the Red-shouldered Hawk throughout much of southern Ontario as a direct result of habitat alteration. However, at QUBS Red-shouldered Hawks remain more numerous than Red-tailed Hawks on most of our tracts.

Figure 1. Number of Red-shouldered Hawks counted along Opinicon Road during the Red-shouldered Hawk and Spring Woodpecker Survey (1991-2010). There is a significant increase in the number of hawks counted between 1991 and 2010 (P=0.0013).

Literature Cited

  1. Cadman, M.D., Sutherland, D.A., Beck, G.G., Lepage, D. and Couturier, A.R. (editors). 2007. Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources and Ontario Nature.
  2. Weir, R.D. 2008. Birds of the Kingston Region 2nd edition, Quarry Press, Kingston.

Hornemann’s Hoary Redpoll

Posted by Mark Andrew Conboy

It’s no secret that QUBS is a great place for birds and birders alike. Enthusiastic birders visit Opinicon Road every spring to search for species that are at the northern edge of their breeding ranges such as Yellow-billed Cuckoo (Coccyzus americanus), Red-bellied Woodpecker (Melanerpes carolinus), Blue-gray Gnatcatcher (Polioptila caerulea), Yellow-throated Vireo (Vireo flavifrons),

redpolls
A female Hornemann’s Hoary Redpoll (right) and a female Southern Common Redpoll (left) at Ironwood Cottage on February 9, 2011. Some of the key field marks are visible in this photo: generally whiter plumage (compared to the Common Redpoll), diffuse streaking on sides, nearly immaculate undertail coverts and a robust head and neck. Photo: Philina English. Please click on photo for larger version

Golden-winged Warbler (Vermivora chrysoptera), Prairie Warbler (Dendroica discolor), Cerulean Warbler (D. cerulea), and Louisiana Waterthrush (Parkesia motacilla). QUBS has also been a hub of avian research for decades, especially for species like Tree Swallow (Tachycineta bicolor), Black-capped Chickadee (Poecile atricapillus), Golden-winged Warbler, Yellow Warbler (D. petechia), Cerulean Warbler, American Redstart (Setophaga ruticilla) and Red-winged Blackbird (Agelaius phoeniceus).
Though the breeding season provides the best birding and is the busiest research season, occasionally interesting and unusual birds show up at QUBS in the winter. This year we’ve had our fair share of notable species including an unseasonable Winter Wren (Troglodytes hiemalis) and a juvenile Golden Eagle (Aquila chrysaetos). But the bird that has attracted the most attention is a Hornemann’s Hoary Redpoll (Carduelis h. hornemanni) which has been visiting bird feeders at QUBS Point on an almost daily basis since February 9, 2011. This 14 g songbird has brought birders from as far away as Pennsylvania, Connecticut, Washington DC and New Jersey. To understand why a Hornemann’s Hoary Redpoll should be so popular among birders it’s necessary to know a thing or two about redpoll taxonomy and natural history.

Redpolls are small finches that breed in the high arctic and subarctic and spend the winter mainly south of the tundra throughout North America and Eurasia. There are two species redpolls in North America, both of which breed in low numbers in northern Ontario and winter in southern Ontario in most years. Redpolls are irruptive during the non-breeding season, which means that in some winters there are lots of redpolls and other winters there are few or none in Eastern Ontario. Annual fluctuations in redpoll numbers are usually correlated with fluctuations in the abundance of food sources, typically birch (Betula spp.) seeds. When seed crops are poor in the boreal forest, redpolls wander south in search of other foods including fodder from birdfeeders.

Whenever redpolls are present, Common Redpoll (C. flammea) is the most abundant species, while Hoary Redpolls (C. hornemanni) are far rarer, so they attract quite a lot of attention from birders when they appear. Both of the redpoll species are comprised of two subspecies (in North America). There is the Southern Common Redpoll (C. f. flammea) and the Greater Common Redpoll (C. f. rostrata); and there is the Southern Hoary Redpoll (C. h. exilipes) and Hornemann’s Hoary Redpoll (there are a wide variety of English names applied to each of these subspecies so it pays to know the scientific names too). The Southern Common and Southern Hoary Redpolls breed across the southern Canadian arctic and subarctic. Greater Common and Hornemann’s Hoary Redpolls breed further north, on Baffin Island, Greenland and in the case of Hornemann’s up to Ellesmere Island! Of the four subspecies, Hornemann’s is certainly the rarest in Ontario. It is only reported in some winters, particularly when there are large irruptions of redpolls.

It’s not uncommon to find both species of redpolls in the same flock, and sometimes three or even all four subspecies can be found together. This winter we’ve recorded all four of the redpoll subspecies at QUBS. Southern Common Redpolls are by far the most numerous with flocks sometimes in excess of 100 birds. Greater Common Redpolls and Southern Hoary Redpolls are seen singly or in pairs within these large flocks. The single female Hornemann’s Hoary Redpoll always appears with other redpolls where it can be easily recognized by comparison with other birds. Compared to the others the Hornemann’s Hoary Redpoll has whiter plumage, less streaking on sides, nearly all-white undertail coverts, more robust head and neck, smaller beak and is noticeably larger.
Its rarity, its size and its extreme northern breeding habitat make Hornemann’s Hoary Redpoll an attractive target for birders, hence the many visitors we’ve received at QUBS in the past two weeks. Redpoll identification can be difficult; in fact it is one of the most challenging identification problems birders face. Direct comparisons between individuals can be helpful and it is necessary to clearly see all field marks in order to properly diagnose which species or subspecies a redpoll belongs to. A good summary of redpoll identification by Ron Pittaway can be found at http://www.jeaniron.ca/2007/Redpolls/redpolltext3.htm.

Strange Goose at Chaffey’s Lock – 3 Years Running

Posted by: Mark Andrew Conboy

For the third winter in a row a peculiar Canada Goose (Branta canadensis) has put in an appearance at Chaffey’s Lock. I first saw this uniquely patterned goose (see picture) over a number of weeks at Chaffey’s Lock in the winter of 2008-09. I subsequently found it paired with a normal-plumaged Canada Goose on a beaver pond in the remote northeast corner of the Massassauga Tract where it was present with its mate and a brood of four goslings in May 2009. In the winter of 2009-2010 I saw it only once at Chaffey’s Lock. The bird was again present among 26 other Canada Geese on December 16, 2010.

Canada Goose abberant plumage
The aberrant plumaged goose that has been frequenting the QUBS region for the past three years. This photo was taken on the Massassauga Tract in May 2009. Photo: Mark Andrew Conboy. Click on image to see larger version.

Aberrant plumage such as in this goose, can be the result of many factors including hybridization, leucisim, albinism, malnutrition and injury. But it can be difficult to say confidently what the cause of strange colouration in individual birds is without close examination in the hand. Although Canada Geese will hybridize with Snow Geese (Chen caerulescens) to produce offspring that have dark and light patches of plumage, this particular bird doesn’t match the typical hybrid plumage or bill shape very well. That this bird sports the same odd plumage each year suggests that it’s not the result of malnutrition or an injury to growing feathers. Perhaps this goose is either partially leucistic or partially albino. Lecucisim is when a bird lacks black pigment in its feathers. Albinism is when a bird lacks all colouration in the feathers and other tissues. Without a closer look at this goose it is hard to say which of the two it might be, but the pink bill and snow-white feathers suggest a partial albino. A more typical appearance for a leucistic Canada Goose is to have feathers that are not so white but instead are a washed-out brown.

Although colour variations such as albinism are not extremely rare in Canada Geese, this bird is an interesting one because its distinctive plumage means that it is possible to glean some information about the life history of a single bird, even if it is only in glimpses from time to time.

Cerulean Warbler now Endangered

Posted by: Mark Andrew Conboy

Cerulean Warbler
The Cerulean Warbler is now a federally endangered species. QUBS is one place in Ontario where this species is actually still rather common. Photo: Philina English. Click on image to see a larger version.

The Cerulean Warbler (Dendroica cerulea) is emblematic of QUBS and the southern Frontenac Arch. It has been the subject of research at the biological station since the 1990’s and indeed much of the basic natural history knowledge biologists have about this canopy-dwelling bird is the result of field work done right here at QUBS. In addition, hundreds of birders flock to Opincion Road and the area around Frontenac Provincial Park every spring to tick this species off their checklists. Cerulean Warblers are therefore a big deal to those of us who live, work and play in this part of the Arch. It’s therefore worth noting that Cerulean Warblers are now classified as endangered in Canada.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) is the governmental body that assesses the conservation status of species in Canada and recommends them for protection under federal species at risk legislation. In November COSEWIC reassessed the status of Cerulean Warbler and upgraded it from a species of special concern to an endangered species. The previous designation (special concern) was conferred in 1993 and reassessed as such in 2003. A species of special concern is one that has not yet become so severely imperiled as to be considered threatened (yet another official level of classification) or endangered but could become so if certain risk factors are not mitigated. Classification as endangered is far more serious and means a species is “facing imminent extirpation or extinction” in Canada (see COSEWIC). There are a number of factors that make extirpation a realistic possibility for Cerulean Warblers. Logging, forest degradation and fragmentation in the wintering habitat (the South American Andes), the apparent rarity of suitable breeding habit in Canada, and continued rapid population decline throughout much of its range since the 1960’s are all cause for grave concern.

COSEWIC reports that there are an estimated 1000 Cerulean Warblers breeding in Canada annually. Intensive field work in May and June this year estimated about 100 breeding pairs (200 individuals) at QUBS. If those estimations are correct then lands owned by the biological station are home to 20% of Canada’s Cerulean Warbler population. The importance of our mature forest tracts which, Cerulean Warblers use for breeding cannot be overstated.

Cerulean Warblers are now classified as endangered on a national scale but still only as special concern provincially; even though nearly the entire Canadian population of Cerulean Warblers breeds in Ontario. However, reassessments of species at risk are ongoing at the provincial level so their classification may or (may not) come into line with the federal list. For an explanation of how the federal and provincial species at risk lists differ click | here |.