Saturday, February 24, 2018

A note on Boreal Owls

There have been at least seven Boreal Owls seen in southern Manitoba recently so we thought it worth a note to the group.  We wanted to ask people to be extra cautious with a Boreal Owl in a seemingly “exposed” roosting  position and not to intervene (these owls need to conserve energy and they sit tight until nightfall, which people sometimes misinterpret as a sign of illness). A longer version of this message is provided below (for those who would like more detail):

Some of the seven Boreal Owls found recently were hunting at feeders (one managed to take a Eurasian Collared-Dove), and a few were injured or deceased (perhaps roadkill).  All that were measured were males. The general area of sightings has ranged from Carman to Ashern but, for obvious reasons, we are not posting the locations in any public forum (remember Manitobabirds is viewable by anyone including non-members). The great popularity of owls these days can be to their detriment.

These Boreal Owl records are not unexpected near the end of a harsh winter. This is presumably a product of this species’ unique “partially migratory” strategy, i.e. females typically move away from the breeding grounds but males try to hold onto their territories as long as reasonably possible (gives them a spring head-start). When the food supply in the boreal forest gets thin, some of these males are forced to leave their territories and they can end up in cities and towns, especially those reasonably close to the southern edge of the boreal forest.  Many such visits are short and the owl moves on in a day or two looking for a new food source.

Some of these owls find themselves in proximity to people, pets and roads (vehicles) and hence at risk. They may appear to roost or perch in “ridiculous” places but these are chosen for reasons such as for sunning, mild heat sources (light, vent or other), wind breaks, and/or proximity to a food source or cached prey. Sadly too often the greatest risk to these owls is people’s good intentions, i.e. people wrongly assume they are ill and try to catch them and bring them in. An owl on or near the ground is one of the most common reasons people try to intervene but there are many good reasons for owls to be on or near the ground (mantling prey or sometimes even “defrosting” prey is one reason and the thermoregulatory reasons discussed above may also bring them low down). Some owls allow close approach but people do not understand the stress such approach causes or the huge risks to small owls if they take flight in the daytime and why they are so reluctant to do so (see: http://artusobirds.blogspot.ca/2014/12/signs-of-stress-in-owls.html). If you do find an owl that you feel is behaving oddly, please don’t intervene but call first. An experienced and trained eye can judge the best course of action. In the vast majority of cases, the very best thing is to leave the owl its space (obvious exceptions would include an owl recently struck by a vehicle).

We welcome details on such records for ongoing research. Thanks for appreciating and caring for our winged wonders!

Christian Artuso (Winnipeg) and Jim Duncan (Balmoral) 

The photo below shows a perfectly healthy Boreal Owl that was perched very low to the ground, which aroused some concern until it became active near dusk:

Sunday, February 4, 2018

Owls of the Indian Subcontinent and islands

This is a brief overview of the owls of the Indian Subcontinent and some of the surrounding islands. It is not exhaustive but represents species seen on a recent trip to southern India and Sri Lanka and a few old slides from a previous visit to India. It is arranged in taxonomic order.
 
Barn Owl (Tyto alba), alternatively Eastern Barn Owl (Tyto javanica stertens), Sri Lanka, © Christian Artuso
            Recent analyses suggest that the Barn Owls found on the Indian Subcontinent should be considered as part of the "Eastern Barn Owl" group (rather than with the Barn Owls of the Europe and Africa). The International Ornithological Committee (IOC) gives the Eastern Barn Owl full species status as Tyto javanica and the subspecies designation of stertens still applies to the birds shown here. I have seen many Barn Owls around the world, and I have long been a fan of these fascinating owls, but I have to say that the golden glowing facial rim on this individual from Sri Lanka just blew me away! So much so that I decided to share three photos of this individual and a fourth of a bird in the nest cavity (all cropped). In the first photo you can see how the bill is pointed downward, as well as the beautiful colour of the back and wings. In general terms (over evolutionary time), the beak in owls has evolved to point downward rather than outward and this has the big advantage of minimising interference with owls’ binocular vision. You can see it especially well note in the photos where the face is in profile here. The second photo is a portrait (cropped to vertical) showing the lightly spotted underparts and the famous heart-shaped face. The third photo shows the owl preening, scratching under the bill. The fourth photo shows another Barn Owl peering out of the nest cavity.


Andaman Masked-Owl (Tyto deroepstorffi), South Andaman Island, India, © Christian Artuso
            Also known as Andaman Barn Owl, the Andaman Masked-Owl (Tyto deroepstorffi) was only recently split from the Barn Owl. This species is endemic to the Andaman Islands (at least to South Andaman but possibly also Middle and North Andaman) in the Bay of Bengal north of Sumatra and west of Burma. The Andaman Masked-Owl is slightly smaller than the Barn Owl with a few interesting features such as very powerful feet, a pinkish wash to the face, a brown facial disk, a very dark mantle, and a golden wash to the upper breast and side of neck. Very little is known of its ecology other than a tendency to roost in caves (now also buildings) and a distribution mainly in the coastal plain of the island. This photo shows a pair (presumed female on the left is slightly darker overall, especially on the underparts, and has more spots on the breast (not known if these differences are consistent). This is a poor-quality photo from a considerable distance but gives a little sense of the palm-filled coastal habitat.

 Sri Lanka Bay Owl (Phodilus assimilis), Kerala, India, © Christian Artuso
            The southern portion of India is home to many of the subcontinent’s owl species and the Western Ghats (small mountain range in southwest India) also share a few endemic or near-endemic bird species with Sri Lanka, including the magnificent Sri Lanka Bay Owl (and likewise the Sri Lanka Frogmouth and others).  The Sri Lanka Bay Owl is one of two Asian species in the genus Phodilus (the Congo Bay Owl is often also placed in this genus but there is disagreement on that). The golden nape and golden highlights on the owl’s back (that you can see in these photos) are one of the features that help separate the Sri Lanka Bay Owl from the similar Oriental Bay Owl (call/song is another). The bay-owls belong to the Barn Owl family (Tytonidae) but they are placed in their own genus, distinct from the Tyto barn-owls, masked-owls and grass-owls (only two genera in the family: Tyto & Phodilus). The bay-owls have several unusual features, perhaps the most striking of which is the way they can raise the top of their facial disk to look like ears (look at the photo of the bird on the day roost to see this, although the “ears” can be MUCH more pronounced than shown here). One hypothesis is that this enables them to mimic a mammal and could be a way to avoid danger (mammals are much heavier than birds of the same size so looking like a mammal could makes a bird seem “bigger”). The bay-owls’ mammalian appearance is really accentuated by the super short tail (usually hidden by the wings creating a blunt rear-end look) and their vertical posture (note how the owl clings to a vertical vine perched upright, with powerful talons, in these photos). If you add the appearance of their HUGE eyes to the vertical posture and facial shape suggesting ears, the whole effect, at least to my eye, makes them look like a small primate. Of course those enormous eyes are of great benefit as they hunt rodents in the dark understorey of the dense rainforest (they seem especially fond of a dense understorey with vines that many owls would find too difficult to hunt in). The Sri Lanka Bay Owl is certainly enigmatic and I was absolutely delighted to see one at night and one by day on this trip to Kerala. Their call is hauntingly beautiful as well and I would highly recommend listening to either the Oriental Bay Owl and/or the Sri Lanka Bay Owl on http://www.xeno-canto.org/. Another point to note is how the bill points downward as discussed above for the Barn Owl..
 

Andaman Scops-Owl (Otus balli), South Andaman Island, India, © Christian Artuso
            There are two scops-owls on the Andaman Islands: the endemic Andaman Scops-Owl and an endemic subspecies of Oriental Scops-Owl. The Andaman Scops-Owl is a smallish scops-owl with two colour morphs, rufous and brown-grey (sometimes called “dark morph”), although there seems to be some differences in the literature in how these are described; for example, I believe this bird is a  “dark” or brown-grey morph but it is similar to the photo in Mikkola’s book that is called a rufous-morph. This scops-owl is found in the forest and open woodlands of South Andaman Island (possibly also other islands in the Andaman group) and, like the other owls of the Andaman Islands is very poorly known.


Serendib Scops-Owl (Otus thilohoffmanni), Kithugala, Sri Lanka, © Christian Artuso
            Only discovered in 2001 and only described to science in 2004, the mysterious and enigmatic Serendib Scops-owl is endemic to the island of Sri Lanka and listed as globally Endangered. This is of course based on its tiny range (only known from ~5 sites in humid forest in southwestern Sri Lanka) and correspondingly small population, both of which are undergoing a decline owing to habitat loss and degradation.  There are certainly fewer than one thousand individuals and there may be as few as 250 individuals of this small owl. One positive aspect is that all five sites where the Serendib Scops-Owl occurs are formally protected but habitat loss near these sites is ongoing. You can see the larger female more clearly than the male in this photo. Being shown this beautiful pair in the superb the Kithugala preserve was a personal highlight for me (and my 140th species of owl seen) especially because of this owl’s mystique and because the last time I was on the Indian Subcontinent the specie was not even known to science.

Indian Scops Owl (Otus bakkamoena), Sri Lanka, © Christian Artuso
            Special thanks to the home owners, whose name I do not know, who allowed us into their yard to see these handsome owls, I get to share this photo of a pair of roosting Indian Scops-Owls from southern Sri Lanka. The nominate subspecies occurs in both southern India and Sri Lanka. The Indian Scops-Owl is widespread in the subcontinent south of the Himalaya (where its congenitor Collared Scops-Owl occurs). Its dark eyes help in identifying it from other co-occurring scops owls such as the Oriental Scops Owl (coming next). The Indian Scops-Owl frequently roosts in dense tangles, as you can see in the second photo below. This photo is heavily cropped.


Oriental Scops-Owl (Otus sunia modestus), South Andaman Island, India, © Christian Artuso
            The other scops-owl on the Andaman Islands is the Oriental Scops-Owl. Oriental Scops-Owl is a widespread species; however, the Andamans are home to an endemic resident subspecies that might warrant full species status, nicknamed “Walden’s Scops-Owl”. Perhaps at some future point genetic and behavioural studies will provide support for full species status of this insular population. The second photo shows the rufipennis subspecies from southern India, which is fairly dark and, as the name implies, with some rich rufous tones in the wing.
 

 

 

Spot-bellied Eagle-Owl (Bubo nipalensis), Kerala, India, © Christian Artuso

            The magnificent Spot-bellied Eagle-Owl, also known as Forest Eagle-Owl, is a large tropical Asian species that is very difficult to observe. Large individuals can be as long as 63 cm making this one of the largest species in Southeast Asia and South Asia (even larger than Indian Eagle-Owl but smaller than Eurasian Eagle-Owl). The Spot-bellied Eagle-Owl  is found from Indochina across the Himalaya and southern China, with a disjunct population in southern India (mainly the Western Ghats) and Sri Lanka (the Sri Lankan birds are said to be smaller and hence often considered a subspecies). This large owl (top predator) eats a wide variety of prey including large birds like pheasants and small-medium sized mammals including the young of small deer species (muntjacs, mouse deer). It has even been recorded taking unusual prey such as jackals and large monitor lizards. It is mostly a cavity nester (although it will use stick nests, caves or cliffs on occasion) and hence reside in forest with tall trees, typically humid evergreen or deciduous forests, or gallery forests in drier areas. It is considered uncommon throughout its range and is very secretive. Despite all my years spent in Asia I had never managed to see one until my recent trip to Kerala (southernmost India). This was one of those times when my stubborn refusal to sleep, preferring to wander off  alone in the forest at night, paid off… one of those truly magic moments when, out of the corner of my eye, I caught a glimpse of a large silhouette crossing a clearing and eventually tracked down the monster perched. The owl was fortunately still in the same area two nights later for a bonus. This impressive owl was perched in the subcanopy and this photo is very heavily cropped. The posture was fascinating too. I have often seen owls perched on one leg when roosting, singing or at rest, but most bend the other leg up or tuck it into their feathers but this owl had one leg hanging down below the perch with the toes seemingly clenched, at least for a short while. I am not quite sure why that was but it is a posture one sees when owls are stretching/preening.

 

Dusky Eagle-Owl (Bubo coromandus), Rajasthan, India, © Christian Artuso

            The Dusky Eagle-Owl is found across the northern part of the Indian Subcontinent and not in the south. This is an old slide of a female incubating. The Dusky Eagle-Owl is intermediate in size between the smaller Indian Eagle-Owl and the larger Spot-bellied Eagle-Owl and characterised by the greyish-brown or "dusky" colouration shown here.



Brown Fish Owl (Ketupa zeylonensis), Yala National Park, Sri Lanka, © Christian Artuso
            The three fish-owl species in the genus Ketupa (although in some taxonomies Ketupa was merged into Bubo) are large owls with shaggy ear-tufts and unfeathered tarsi. A couple of points to note: 1. the “fish-owls (genus Ketupa) are not the same as the “fishing-owls” (three African owls in the genus Scotopelia that are also large but lack ear-tufts); and 2. The Blakiston’s Fish-Owl may not have changed its English name but it is no longer considered to be a Ketupa fish-owl but instead a Bubo eagle-owl that has evolved to catch fish. The Brown Fish-Owl shown here is the most widespread of the Asian fish-owls, its main range being from Pakistan to southern China, but with disjunct populations as far west as Turkey. The photo shows one of a roosting pair (the second bird was much more hidden in the foliage) in Yala National Park, Sri Lanka (the nominate subspecies occurs on Sri Lanka). The first three photos below wer taken from the jeep (for obvious reasons it is best to stay in the vehicle to minimise the risk of disturbance, and getting out of the vehicle is not permitted in this park) and is heavily cropped. I added a fourth photo of another Brown Fish owl being mobbed by Large-billed Crows in Kerala, India (don't be fooled by the "smiling" appearance).







Tawny Fish Owl (Ketupa flavipes), Uttarakhand, India, © Christian Artuso
            The Tawny Fish-Owl is slightly larger than the Brown Fish Owl and more northern in its distribution. Once again without getting out of the jeep, I took this record shot in Corbett National Park but the owl was not interested in turning its head to show me its face.


Asian Barred Owlet (Glaucidium cuculoides), Uttarakhand, India, © Christian Artuso
            The Glaucidium species in Asia are often called "owlets" (rather than pygmy-owls as in the Americas). The Asian Barred owlet is widespread and will be familiar to many Asian readers as it is crepuscular and partially diurnal and hence easier to see than many of the owl species of the subcontinent. It is found across the Himalayan region (unlike the Jungle Owlet below).


Jungle Owlet (Glaucidium radiatum), Kerala, India, © Christian Artuso
            Many travellers to India hope to see “big stripey” (tiger) but, pound for pound, the “little stripey” Jungle Owlet is equally ferocious. Like most species in the Glaucidium genus, usually referred to as “pygmy-owls” or “owlets”, they are capable of taking prey larger than themselves and they  often elicit a strong mobbing response from small birds. The Jungle Owlet is endemic to the Indian Subcontinent but widespread within the subcontinent. Its bold striped pattern with strong rufous highlights in the plumage is exquisitely beautiful. This species is largely crepuscular (active and dusk and dawn), which gives opportunities to see it in daylight. I had such a hard time choosing between the many photos I took of this species on my recent trip to southern India and Sri Lanka that I have ended up with six photos, three  of adults from Kerala, India and one of an immature bird from Sri Lanka. These photos show:

* An adult perched head-on showing the barred underparts
* The same adult in a profile view showing the rufous in the wings
* The same adult in a profile view showing the back of the head and the absence of the false face in some of the large Glaucidium from Asia and Africa (one of the reasons they are sometimes considered a separate genus)
* Another individual facing forward and calling showing the white throat feathers
* A habitat show showing an adult against the backdrop of the forest (gives a sense of the little owl in the big forest)
* An immature bird (from Sri Lanka) that has probably only recently gained independence from its parents.








Chestnut-backed Owlet (Glaucidium castanotum), Kithugala, Sri Lanka, © Christian Artuso
            This Chestnut-backed Owlet looked a little comical when singing – almost as though the owl was literally laughing its head off! The rich chestnut back, which contrasts so strongly from the rest of the plumage, is very eye-catching, so I am sharing four photos to show this feature from slightly different angles (all are cropped and one is cropped to vertical format). This tiny little owl is an endemic to the island of Sri Lanka, and, although mostly found in the humid forest zone, is a little more widespread on the island than the Serendib Scops-Owl (see above). It is listed as globally Near-threatened because of its restricted range and declining population.






Spotted Owlet (Athene brama), Rajasthan, Sri Lanka, © Christian Artuso
            The Spotted Owlet is widespread and common throughout most of the subcontinent, except parts of the deep south. Despite the name "owlet" it in an Athene species and related to the likes of Little Owl and Burrowing Owl. It is somewhat crepuscular and relatively easy to observe.





Mottled Wood-Owl (Strix ocellata), Kerala, India, © Christian Artuso

            The Mottled Wood-Owl is an endemic of the India Subcontinent and arguably one of the most exquisitely plumaged owls in the world. The dappled mottling with golden highlights against greys and browns (the nape is particularly eye-catching) have to be seen to be believed. This owl is somewhat of a habitat generalist, using a variety of woodland types, although in only occurs in the lowlands. It is also a diet generalist and east everything from small insects to small mammals and birds. Nonetheless it is not particularly common and very little is known of its overall population numbers and trends.


Brown Wood-Owl (Strix leptogrammica), Kerala, India and Sri Lanka © Christian Artuso
            The beautiful Brown Wood-Owl is another exceptionally beautiful Asian wood-owl (genus Strix), with an exquisite contrast in the rufous facial disk (from the rest of the plumage). This album contains three photos (all heavily cropped), one from Kerala in southern India (indranee subspecies) and two images of a pair at their roost site in Sri Lanka (ochrogenys subspecies). The photos from Sri Lanka show a pair, the first is cropped and the second cropped even closer to show the single bird better. Interestingly, these photos show more examples of owls roosting on one foot, which seems a common behaviour. The Brown Wood-Owl is quite large (size varies with sex and subspecies but can be as much as 40 – 55 cm in length) and uses a wide variety of forest types at a variety of elevations.

Short-eared Owl (Asio flammeus), Rajasthan, India, © Christian Artuso
            The Short-eared Owl needs little introduction as it is one of the most cosmopolitan of owl species. In the Indian subcontinent, it seems most prevalent in arid areas and grasslands. The last of these photos shows an aggressive interaction with a Pallid Harrier.
 
 

Brown Boobook (Ninox scutulata), Kerala, India, © Christian Artuso
            The genus Ninox (now often referred to by the onomatopoeic word "boobooks") is predominantly Australasian but there are a few species in Asia.  The most widespread Asian species is the Brown Boobook, formerly and sometimes still called Brown Hawk-Owl and affectionately known in many parts of Asia as the "du-wup bird" for its two-note song; the same two-note pattern that engendered the name "boobook" for the Southern Boobook (Ninox boobook) in one of the Australian indigenous languages, although it is not clear from which of the many Australian languages). 

Andaman Boobook (Ninox affinis), South Andaman Island, India, © Christian Artuso
            There are two endemic Ninox species on the Andaman Islands. This is the smaller Andaman Boobook, also known as Andaman Hawk Owl. It is smaller than the similar-looking and widespread Brown Hawk-Owl and also smaller than the Hume’s Boobook that it shares the islands of South Andaman with. This species is a resident of the islands forests and uses both primary forest and se­condary forest. It is poorly known but insects probably form the bulk of its diet.


Hume's Boobook (Ninox obscura), South Andaman Island, India, © Christian Artuso
            Easily identified by its darker colour, especially the rich coffee-coloured and unmarked underparts (as well as large size), the Hume’s Boobook is the second endemic Ninox species on the Andaman Islands. The two endemic boobooks, Andaman Boobook and Hume’s Boobook, overlap in distribution and habitat. This individual was photographed just a few hundred metres away from the Andaman Boobook I posted yesterday. This suggests some segregation in resource use and Hume’s Boobook seems to prefer more open habitats (this bird was in a rural yard) and is known to prey upon birds in addition to insects (e.g. capturing swifts in their nesting caves). Both species are very poorly known and even their distribution on the various islands of the Andaman Island group is unclear.



 
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