Category: Wildlife

Those ill-informed osprey — feedback

cat-kills-bird

On Sunday, I posted a short iPhone video of an osprey nest next to an 800 kw wind turbine at River John, Nova Scotia, to make the tongue-in-cheek point that someone forgot to tell the osprey about the perils of infrasound and shadow flicker. The point was tongue-in-cheek in the sense that I have no way of knowing whether young birds successfully fledged from the nest, but serious in the sense that I think health arguments against wind turbines are largely spurious.

Bruce Wark, former reporter, CBC radio producer, and King’s journalism professor, thinks I overlooked the most obvious threat wind farms pose for Osprey and other birds:

Here’s an excerpt from a scientific abstract based on a study by K. Shawn Smallwood in the peer-reviewed publication Wildlife Society Bulletin: “I estimated 888,000 bat and 573,000 bird fatalities/year (including 83,000 raptor fatalities) at 51,630 megawatt (MW) of installed wind-energy capacity in the United States in 2012. As wind energy continues to expand, there is urgent need to improve fatality monitoring methods, especially in the implementation of detection trials, which should be more realistically incorporated into routine monitoring.”

These numbers sound shocking. Indeed, I think they are presented in a contextless way* that insures they will shock. But they are actually surprisingly low, especially for birds. He estimates 573,000 bird fatalities for year based on an installed capacity of 51,630 megawatt (MW) If we assume 1 MW/turbine, the average turbine kills about 10 birds a year.

Whenever you hear numbers like this, it’s always useful to ask, “compared to what?”

Compared to what energy sources? The large array of windows on the south side of my passive solar house kills more than 10 birds a year. More to the point, the coal-fired power plants in Nova Scotia that could be displaced by wind power destroy bird habitat, cause deleterious climate change, and release pollutants that must impact mortality among birds with their supercharged respiratory systems. Gas does the same, only less so (or possibly less so, depending on methane leakage during production and transmission). Hydro dams destroy wildlife (including bird) habitat.

Compared to what other causes of human-assisted bird mortality? In a paper published in the journal Nature,** Peter Marra of the Smithsonian Conservation Biology Institute in Washington, D.C., estimates that domestic and feral cats kill between 1.4 billion and 3.7 billion birds per year, along with 6.9 billion to 20.7 billion wild mammals per year in the US alone.

Taking the median of Marra’s ranges, we can say that US cats, feral and domestic, kill about 2.4 billion birds and 12.4 billion birds per year. Marra estimates the US cat population at 114 million, so each cat kills an average 21 birds per year—making a cat twice as lethal as a wind turbine (without even counting the 101 mammals an average bird cat kills per year).

Wark was kind enough to respond to these points:

In my Coast cover piece on wind, I stayed away from birds and bats because, as you point out, the relative numbers are low especially compared to cats. I concede that point. However, the reason I responded to you is that you were trying to use the osprey nest video to make a questionable point, i.e. that noise and flicker must not be as big a problem as wind turbine opponents claim because an osprey had built its nest near one of them. A more telling point from the opponents’ perspective is that the osprey risks flying into the turning blades as it navigates around the turbines near the nest.

I think where you and I would agree is that we consume too much electricity and that there is no environmentally costless way of producing large amounts of it. People pin their hopes on wind and hydro because they’re supposedly “clean and green” and so, the reasoning goes, if we could only kick our dirty coal habit and use wind and water instead, we’d be able to “save” the planet without having to cut our consumption too much. It’s the same reasoning environmentalists use when they contribute to various “save the planet funds” to offset their addiction to air travel. As I see it, the problems involved in cutting consumption are compounded by the fact that our economy depends on it so we’re caught on a treadmill where household spending fuels growth, jobs and all the other hallmarks of “prosperity.”

I do agree with Wark that there is no costless way of producing large amounts of energy, but the environmental cost of producing it with coal dwarfs the cost of doing so with wind, hydro, solar, nuclear, and probably outstrips that of doing it with gas. If it is true that we face planetary disaster owing to human induced climate change, then it is irresponsible to dwell of what are really NIMBY objections in disguise.

* This comment applies only to the abstract of Smallwood’s paper. Unfortunately, the Wildlife Society Bulletin follows the increasingly common and lamentable practice of putting the full text of its studies behind a paywall. It’s possible that, in the full text, Smallwood contextualizes the numbers that seem so sensational in the abstract.

** The full text of Marra’s paper is likewise behind a paywall.

 

 

Whose breakfast will I be?

 ©2013 Ronnie D'Entremont - Reproduced by permision

Things went from bad to worse for a young smelt herring in West Pubnico Saturday morning. A common tern and a green crab had their eyes cocked for a meal when he happened by. My guess is that herring and green crab both fulfilled their destinies as breakfast.

Nova Scotia Bird Society stalwart Ronnie D’Entremont was on hand to capture the action with this once-in-a-lifetime shot. Nova Scotia has a lot of wonderful nature photographers, but Ronnie ranks with the best.

Photo copyright ©2013 by Ronnie D’Entremont. Reproduced by permission. All rights reserved.  Click the image for a higher-res version.

Eyes on the shore

A Grey Seal surveys the shoreline at Whale Cove, Inverness Co., Saturday. (Click photo for larger image.)

Photo: Joshua Barss Donham.

Watchfulness

A bald eagle surveyed the shoreline of St. Patrick’s Channel from a red oak tree in the Waycobah First Nation at 2 p.m. Monday. Photo: Joshua Barss Donham

The seventh starling

Last November, a series of Contrarian posts depicted the mesmerizing spectacle of starling murmuration: the undulating patterns made by starling flocks in flight (here, here, and here). Beyond their intrinsic beauty, these scenes provoke a sense of wonder: how do they do it? How do the hundreds of individuals who make up a flock of birds (or a school of sardines, or a swarm of midges) know how to execute their particular roles in the collective ballet.

The standard explanation, recounted by a pair of Italian physicists who have studied the question [PDF], runs like this:

[T]his collective behaviour stems from some simple rules of interaction between the individuals: stay close to your neighbours (but not too close!) and align your velocity to theirs. There is neither a central coordination (a leader), nor any “collective intelligence,” but a distributed behaviour from which coordination emerges. This is the essence of self-organisation.

Unfortunately, as Andrea Cavagna and Irene Giardina acknowledge, these purported rules of interaction boil down to, “just an educated guess as opposed to a well-established scientific fact. Moreover, they are generic and vague.” While computer models based on these rules produce, “swirling dots on our computer screen that look roughly like a flock of birds,” this is “hardly satisfactory science.”

Cavagna and Giardina led an EU-funded research project called STARFLAG (Starlings in Flight) that used stereoscopic cameras to produce 3D images of a real starling flock in motion. This gave them empirical data they could use to see how the birds actually interact in flight.

The clearest structural feature is that a bird’s nearest neighbours are typically found at the bird’s sides, rather than ahead or behind the bird, so that the probability that a bird’s nearest neighbour is approximately ahead or behind is very low. The reason for this is either the anisotropic visual apparatus of starlings—with eyes on the side of their heads they see better sideways than fore-and-aft—or a sort of “motorway effect,” by which birds keep a safe frontal distance to avoid collisions.

This “anisotropic” quality — think of it as side-by-sidedness — declines with distance. A bird’s closest neighbor is directly to its side, the second nearest slightly less so, the third nearest even less so.

The results of this measurement were surprising. All existing models and theories of collective animal behaviour have assumed that each animal interacted with all neighbours within a fixed distance. The STARFLAG data showed something quite different: each bird interacts with a fixed number of neighbours, irrespective of their physical distance. This number is approximately equal to seven. The difference with the assumptions of the models is stark: the data show clearly that the distance within which birds interact is not fixed at all, but rather it depends on the density of the flock. In a packed flock, the seven neighbours you are interacting with are close to you, whereas in a loose, sparse flock they are more distant.

Starlings, and perhaps other schooling, swarming, and flocking critters, perform their complicated pirouettes by adjusting their speed, and staying close but not too close, to their seven nearest neighbors. The critical point, Cavagna and Giardina found, is that the birds interact with a fixed number of nearest neighbors—not, as had been previously supposed, with all neighbors within a fixed distance. This turns out to give them the evolutionary advantage of greater protection from marauding hawks.

By interacting within a fixed number of individuals, rather than meters, the aggregation can be either dense or sparse, change shape, fluctuate and even split, yet maintaining the same degree of cohesion. Thus, the topological interaction is functional to keeping the cohesion in the face of the strong perturbations a flock is subject to, typically predation.

HT: The two Daves