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Monday, April 14, 2014

The Sex Life of Crows

By Sharon McInnes

If the title of today’s column made you sit right up and take notice (that was, I admit, my goal), I should warn you that for crows, getting to sex isn’t simple. It involves a lot of planning, preparation, and patience. As Kevin McGowan explained in the webinar “The Secret Life of Crows”, before a crow can land a mate, he has to find a suitable breeding territory. (Scientists call this ‘acquiring breeding status’.) That can be a big job.


American Crow
Photo by Kevin McGowan


Here’s how it works. Let’s say you are, for example, a male crow and you live in the city. Unlike most other species of birds, you could stay home for up to six years, helping to raise your brothers and sisters. Your tasks would include helping with nest-building, feeding, and chasing predators away. (A lot of male crows do this; females tend to leave home much earlier.) Called ‘cooperative breeding’, this strategy is almost as advantageous to your extended family – and to crows in general – as having your own offspring. McGowan says of crows that practice cooperative breeding: “Some of these families are amazing. One marvellously successful crow family lives at St. Catherine’s Church in Ithaca – a breeding pair and up to seven generations of siblings live on or next to the home territory there.


A Family of Crows
Making dinner plans? Discussing a territorial dispute? Gossiping about a neighbour?
Photo by Junior Libby - CC license. 


And there are substantial rewards for staying home to help. One is that you’re more likely to inherit your parents’ territory when they die. In the meantime, they might allow you to use part of their breeding territory to raise your own family. But don’t get excited too quickly. You won’t be getting started in that venture for a while: the average age of initial breeding in McGowan’s study was 4.9 years.

If the ‘one big happy family’ scenario doesn’t turn you on, you have options! One is to find your own territory. Since you live in the city you’ll need about 10 acres. (Country crows tend to have much larger estates.) Of course it needs certain attributes. For one thing, it has to be available. You don’t want to have to battle another crow that’s already set up house there. And it must have plenty of food nearby. (I know – you’re a ‘city crow’ and you’ll eat anything. But your babies need nutritious food – the same kind they’d be getting if you lived in the country.) 

No? Well, if trying to establish your own territory sounds risky, you could join an already established group. This has potential, especially down the road. For example, when the male adult of the mated pair you join dies, you could simply replace him. No need for the widow to go hunting for a new guy when you’re there, ready, willing, and able, right? Or, in another scenario, they might both die, and you could inherit their territory.

Or maybe one of your older siblings has already struck out on his own and would welcome your help?  Or maybe a friendly neighbourhood crow? However be aware that neighbours – especially helpful ones – are known to be philanderers. So if you decide to share the territory of a neighbour, there’s a chance (up to 20 per cent) that at least one of your babies might look more like him than you. Then again, I’d be remiss if I didn’t mention that the same hanky-panky is known to happen between relatives. So you can’t necessarily trust your woman with your brother or cousin or uncle either.  And I hate to even bring this up, but if you and your lady stay together for a few years, and have a few babies, there is a chance that she and one of your sons will get together one night. BUT of all the philandering that goes on amongst crows (scientists refer to this behaviour as ‘extra-pair copulation’) only 3.5 per cent of it is between mother and son. That’s heartening, right?

Still, there’s a good reason for sticking close to home to raise your family: crows that do are more ‘successful breeders’. Compared to robins, for example, which have a 25 per cent nest success rate, the American Crows that McGowan studied had a 60 per cent success rate. Those are pretty good odds, for a bird.



This article was first published in The Flying Shingle (www.flyingshingle.com) on April 7 2014

Big Clean Windows, Little Dead Birds

Most of us know about the "Bird Strike" problem. A bird sees reflected scenery (in a window) and flies into it. Hits the glass. Thunk. Broken neck, dead bird.

Sometimes the bird is "just stunned" and eventually "recovers" but often dies later of internal injuries or other injuries that render it less able to survive in the wild.

There ARE solutions! One is BirdTape from the American Bird Conservancy. I just ordered some to install on the windows of our new Garden Room. It's inexpensive and research-based.


To read about ABC Bird Tape (and order it) click here

For more on the seriousness of the problem, check out this article in the Birds on the Brain blog. Even though this piece is about Duke University in the States, the problem exists EVERYWHERE, even here on little old Gabriola Island!


Wednesday, March 26, 2014

The Galveston Bay Oil Spill

On the ABA blog today, Laura Erickson writes about the recent Galveston Bay oil spill: 

"The March 22 spill of 168,000 gallons of highly toxic bunker fuel into Galveston Bay can be expected to take a huge toll on migrating, nesting, and still-wintering birds." 

Click below to read the article: 
The Galveston Bay Oil Spill - what we birders can do

Note: the same thing could happen here. In fact, with every additional tanker sailing the Salish Sea, the stakes go up ... way way UP. 



What would Kinder Morgan's proposed pipeline expansion mean for the billion birds of the Pacific Flyway?

It would mean very bad news, not just when there's a spill but from chronic oiling that happens as a matter of course when oil tankers habitually traverse a waterway like the Salish Sea.

CRED BC (http://credbc.ca/) has done some excellent work on the history of spills and leaks along the existing Trans Mountain Pipeline and on the economic risks and benefits of Kinder Morgan's proposal to expand the pipeline. The following two graphics are theirs.



And I wrote about the issue in a Bird Canada article last month. You can read it here.




Thursday, March 20, 2014

A Bouquet of Crows

by Sharon McInnes

During a Cornell Lab webinair called The Secret Lives of Crows, our instructor, Dr. Kevin McGowan, urged us to avoid the term “a murder of crows” on the basis that it’s unscientific and perjorative.  He’d prefer, he said, “a bouquet of crows. ” So, in honour of McGowan’s more than 25 years studying the social and reproductive behaviour of the American Crow (Corvus brachyrhynchos), a bouquet it is.

American Crow
Wikipedia image

McGowan does his research in Ithaca New York, home of Sapsucker Woods and the Cornell Lab of Ornithology. Here on Gabriola, we have the Northwestern Crow (Corvus caurinus) which is slightly smaller than the American Crow and has a more nasal call but “is so similar that the two may in fact be the same species.” (http://www.allaboutbirds.org/guide/Northwestern_Crow/id) Given the similarities, I think it’s fair to assume that his findings apply to our local crows too.

Three Northwestern Crows conferring.
Photo by Junior Libby - CC license. 

For decades now, crows have been making headlines when they roost, in the tens of thousands, in cities. A 2010 article in The Vancouver Sun refers to that city, my home town, as “The City of Crows”. Certainly when I stay at my daughter’s in the West End, I’m regularly awakened by the raucous calling of crows, and cannot take a walk along the seawall without crossing paths with dozens of them. But it hasn’t always been like this. Crows only started moving into cities, in large numbers, in the 1980s. During the webinair McGowan explained that this press into urban environments had multiple causes but was due in part to the fact that hunting is banned in cities. Crows have been hunted – by farmers and “sport” hunters – since the dawn of time, and still are, as this 2009 post by a Pennsylvania hunter, Bob Aronsohn, attests:

Then my friend … and I shot an additional 6,932 crows from November to February.  Our largest shoot last season was 543 crows in one day. We had several over 400 and quite a few in the two and three hundred range. The main reason I love to hunt crows so much is because you just don't setup just anywhere and expect to have a good shoot. It takes plenty of scouting in order to line up a good shoot. I don't get good shooting all the time, sometimes I just don't get in the right spot.  (http://www.gofoxpro.com/site/crow-hunting)

So, who can blame the crows, intelligent, social, family-oriented beings that they are, for choosing to leave the country?  Besides safety from hunters, city living offers the advantages of readily-available food (since crows have adapted to scavenging our leftovers) and fewer predators such as raccoons, jays, squirrels, owls, and hawks, an asset that is especially important during nesting season. McGowan’s research shows that city and suburban nests are subject to less predation than rural nests. In total, 57% of city nests compared to 48% of rural nests are successful.  

There are also disadvantages, though, to leaving one’s home in the country. For one thing, that city ‘fast food’ is less easily digestible than the crow’s natural diet: invertebrates, fish, snakes, frogs, small birds and mammals, bird eggs, nestlings, fruit and seeds.  Besides being less nutritious, the garbage that crows ingest in cities also carries the risk of contamination. This may not be a big deal for an adult crow but it can be deadly for a nestling.

In the end, though, the advantages and disadvantages of the two habitats appear to cancel each other out, in terms of nesting success, and they end up with the same number of fledglings.  Even though fewer rural babies survive, the ones that do are bigger than their city counterparts.  They’re heavier by 40-50 grams, have longer legs and bills, and possibly (although this not yet proven) larger brains.  McGowan and his team wondered: what makes the difference?  Turns out it’s all that good old country food. Researchers discovered this by feeding their city crows the kind of food mama crows would feed their babies in the wild. The result? Bigger nestlings.  It seems that crows, like humans, will eat junk food, to their detriment, just because it’s there.

This article was first published (with fewer images)
in the Flying Shingle on March 10 2014. 


Thursday, February 13, 2014

2013 Christmas Bird Count - Gabriola Island Results

by Sharon McInnes

In 1,199 communities all over the Americas, for one day between Dec 14 and January 5, hordes of birders got up at dawn to count birds. This year’s count, which took place on Dec 29 on Gabriola Island, was the 114th, making the Christmas Bird Count (CBC) the longest-running Citizen Science project and wildlife census in the world.  In total, 28,644,830 individual birds were counted. On Gabriola, where the count includes only the north half of the island, birders counted 74 species and 3326 individual birds. These numbers don’t reflect the actual number of species or birds on the island (even on the north end), just those spotted by a counter.   

Dark-eyed juncos sittin' in a tree
Count them, count them, how many do you see?

This year’s numbers were significantly lower than last years (3326 compared to 4786), in part because of last year’s Pine Siskin irruption of 1239 birds. (This year only 6 siskins showed up.)  

Pine Siskin numbers plummetted this year

Differences in totals also result from transient flocks of waterbirds. For example, this year there were half the number of Mallards (114 compared to 239). But last year, counters tallied up 175 American Widgeons compared to a whopping 459 this year, and many more cormorants, both Double-crested and Pelagic. (2012: 35 DC cormorants; 2013: 81. 2012: 9 Pelagic; 2013: 16.) 

Many mallards - these ones at Reifel Bird Sanctuary in Delta BC

Also, this year 10 fewer adult bald eagles were counted (down from 22 to 12) and 14 fewer feral turkeys, which are not official count birds but which we can’t seem to resist counting anyway.  

Yes, we know they don't "count". But we count them anyway!

One of the frustrations of any one-day count is that birds don’t always cooperate.  For example, no Red Crossbills showed up in the right locations at the right times to be counted this year. And last year 23 Trumpeter Swans were seen, but this year none. (On the other hand, I counted 14 at Coats March on January 13.) And one islander saw a Northern Goshawk a few days before the count, but on Count Day, no such luck.

In the passerine world, this year there were at least 50% more Northwestern Crows (from 19 to 32), American Robins (from 34 to 99), Golden-crowned Sparrows (from 29 to 47), and Varied Thrushes (25 to 88). 

One cold Varied Thrush, doing his best to keep warm

And the number of Anna’s hummingbirds went up slightly, from 26 to 28.

Anna's hummingbird. From 26 to 28 this year.
Photo by Alan Vernon, CC license. 

On the other hand, there were 50% fewer Hairy Woodpeckers (from 6 to 2), Pileated Woodpeckers (from 14 to 9), Common Ravens (from 101 to 56), Chestnut-backed Chickadees (from 297 to 111), Fox Sparrows (from 17 to 10), Red-breasted Nuthatches (from 78 to 38), Bewick’s Wrens (from 16 to 1), Dark-eyed Juncos (from 303 to 120), Bushtits (from 21 to 0), Red-Winged Blackbirds (from 25 to 1), House Finches (from 109 to 11), Purple Finches (from 7 to 1), Red Crossbills (from 17 to 0), and House Sparrows (from 4 to 0).  

Fox sparrow on a snowy limb

Male House Finch stopping for a drink at one of our bird baths

One of the more exciting finds this year were 3 Marsh Wrens, 2 of which were spotted (after a lot of cloak and daggery and wet feet) at Coats Marsh.  

Marsh Wren.
Many thanks to Don Wigle for gorgeous photo. 

Other unusual birds (possibly considered rare) spotted this year included Mourning Doves on El Verano and a White-throated Sparrow.  

Mourning Doves at Sapsucker Woods in Ithaca New York

So, what’s the point of all this? Why drag oneself out of bed at dawn to venture out in the cold of winter to count birds? According to the folks at Audobon, organizers of the  Christmas Bird Count, the information gleaned from the annual counts is used, in combination from data from other Citizen Science projects, to help scientists assess the health of bird populations and to guide conservation action. Over the years, they’ve learned, for example, that “Birds are not Climate Skeptics, having spoken with their wings.” (Audobon website). They’ve learned which bird populations are in decline (e.g. Rufous Hummingbird, Northern Pintail, Horned Lark, Boreal Chickadee, Common Tern, Evening Grosbeak, Sage-grouse) and which have come back from the brink, thanks to Endangered Species legislation (e.g. Bald Eagle, Peregrine Falcon) and how far and how quickly West Nile virus spread. So, really, maybe it is worth the early morning traipse through the woods in the middle of winter. Thankfully, it is for the tens of thousands of people who participate in the annual Christmas Bird Count.     

This article was first published (without all the photos) in
The Flying Shingle on February 10 2014. 
All photos not otherwise credited are by Sharon McInnes.
Please contact using comment function below for permission to use.

Wednesday, January 15, 2014

Can You Tell an Anna's from a Rufous?

by Sharon McInnes

We have a pair of Anna’s hummingbirds in the yard this winter. If you, too, have hummers right now, here on Gabriola Island, they’re also Anna’s, the beauties that Cornell’s All About Birds site describes as “more like flying jewelry than birds”. 

Male Anna's. Photo by Alan Vernon.
CC license. 

Anna’s have been over-wintering in BC only for the past twenty years or so. Before that they lived exclusively in California and the Baja. But starting in the 1930’s, they began expanding their range northward, probably as a result of more and more backyard feeders as well as the growing popularity of exotic trees, such as eucalyptus, that provided both nectar and nest sites. Some birders worry that feeding Anna’s will interfere with migration. Here’s what the Rocky Point Bird Observatory scientists say on the subject: 

Do not worry! Feeders will not stop a bird migrating, a process that is triggered by the bird's internal clock and levels of sunshine. Anna's are with us year round and their presence at feeders has just become more obvious because their numbers are increasing locally.” (http://rpbo.org/hummingbirds.php)

In the spring and summer, we have both Anna’s (Calypte anna) and Rufous hummingbirds (Selasphorus rufus) on Gabriola. You can tell them apart by their colouring. The sure-fire give-away is that the Anna’s has no rufous (orangey-brown) plumage anywhere, and has little white spots around the eyes. Once you know you’re looking at an Anna’s, you can readily distinguish male from female: the male’s red gorget, or throat patch, extends right over his head, making him a sparkling redhead when the sun shines on his iridescent hood. Striking emerald green plumage covers his back and bleeds onto his sides and white belly. The female, not as showy, is mostly emerald green and grey in colour with a small iridescent red gorget on the throat.

Male Rufous hummers - note the bright red iridescent gorget
and the rufous (brownish) plumage

The female Rufous hummer has a little rufous colouring
on its sides but no shining red throat patch

The female Anna's has no rufous colouring anywhere.  

Does size matter?
It does if you're a hummingbird facing down a House Finch! 

In the spring, the male Anna’s performs a wild and wonderful courtship display.  From as high as forty metres, he does a nearly vertical dive downward, all the while eyeing the female. (On sunny days, he orients his body to take advantage of the sun reflecting on his iridescent throat and crown.) As he comes to a stop, he emits a short high-pitched explosive squeak (more on this later) then “chases” her (she has, by now, indicated her interest, somehow) while she leads him to her nest site. (Wiley little thing.) The female then perches and settles in to watch the show while the male does his “shuttle display”, swinging back and forth about half a metre above her, singing like crazy. All this lasts only about twelve seconds, does the trick, apparently. 

More now about that high-pitched squeak: until 2008 the source of this sound was a mystery. Then student researchers at the University of California used ultra-high-speed video cameras to film Anna’s in action, and discovered the squeak was made not by the hummer’s throat but by his tail feathers. (More here). In cold weather, though, all that matters to a hummer is staying alive. 

This Rufous hummer got caught
in a surprise snowfall one spring

Not all do, of course.  But if you have a feeder up, there are things you can do to help. Most importantly, keep the nectar from freezing. (What’s more heartbreaking than seeing an Anna’s sitting on the perch of a feeder with frozen nectar inside?) Some people (me included) have two or three feeders they rotate as needed, one in the house, staying warm, one outside, getting cold. When the outside feeder gets very cold (or freezes overnight) bring it in and replace it with the other one. Some people keep their feeders from freezing by placing homemade warmers, often concocted from light bulbs, just under the feeder. (I’d like to use my birdbath heater to keep the nectar from freezing but haven’t figured out how to do that yet.) Others wrap feeders in pipe insulation or beer mug insulators or even woolen socks. Many people use a sweeter than usual solution (3 sugar to 1 water) in winter because it doesn’t freeze as quickly as the 4-1 solution. Whatever you do to keep the nectar from freezing, be sure to place your feeders a good distance apart so that the hummer has to fly (thereby creating body heat) to get to them. 

A version of this article was first published in The Flying Shingle on January 13 2014.