Stream monitoring, floodplain analysis, Shade-o-lator, Salmon assessment

As part of our ongoing commitment to environmental uplift, we are offering baseline surveying for riparian ecosystem health.

We are working with The Willamette Partnership’s Ecosystem Credit Accounting System tools, designed for a rapid assessment of stream and floodplain health. These tools were designed for use in calculating offsets for ecological impacts and in the emerging marketplace on ecosystem credits. However, they may also be used for rapid monitoring of watershed improvement projects or baseline surveys to target critical areas for improvement. For ecosystem credits, a landowner may choose to restore riparian habitat instead of farming marginal fields, and sell these credits in the ecosystem marketplace for profit. These tools are also being considered by the forest service as rapid assessment tools to measure management objectives on the forest. For more information, contact the Willamette Partnership.

The Floodplain Analysis tool is designed to measure habitat qualities, and can be used to offset impacts to endangered or threatened species, migratory birds, or other species of interest. It also makes a great quick tool for measuring the current habitat values of a landscape, and targeting particular management activities for restoration.

The Shade-o-lator is the approved tool for measuring temperature credits along a stream. These credits can be sold to municipalities and industry to offset water temperature impacts. Water temperature is, of course, a critical component of stream health since it effects dissolved oxygen (necessary for fish), bacteria turnover, and algal growth. The underlying model was developed by Oregon’s Department of Environmental Quality.

The Salmon rapid assessment tool is specifically developed for the Pacific Northwest west of the Cascades. It was developed to characterize components important to endangered and threatened salmonids (such as Chinook and Steelhead). This tool measures critical components related to stream complexity, resting and thermal inputs.

These tools can be applied to a single piece of property or to multiple ownership lots.

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Why do birds get killed by wind turbines?

Lots of birds get killed by wind turbines—at least that is what you might think listening to the dire warnings about the environmental impact of wind turbines. The fact is that birds do get killed by wind turbines, but far fewer than you might think. As the American Wind Energy Association points out , many fewer birds are killed by wind turbines than by power lines, roads, or housecats. Unfortunately, that excuse is a red herring. It is like saying “Bobby stole a candybar” when the store clerk catches you stealing a piece of Hubba Bubba bubble gum.

The real question is: Are bird mortalities from wind farms an issue of concern from an environmental standpoint? The answer is perhaps. It depends upon how many birds are impacted, and which species. Two major components go into determining how many birds are killed–the first involves the location of the wind farm; the second is determined by bird behavior.

In this blog, I will be focus on the general reasons why birds get killed at wind turbines. I will also talk a little bit about how many birds are actually killed. Look for a discussion on the first question—wind turbine location—in a follow-up blog.

Driving a Bird to Work
So what makes birds run into turbines? I have a simple analogy to use when explaining bird kills to friends- just think about automobile accidents. When you get in your car to drive to work, you don’t expect to get into an accident. As a matter of fact, the odds are very low that you will have any kind of accident (about 1 in 100,000). When you multiply that by the million-or-so drivers on the road in a fair sized city, it becomes a virtual certainty that someone will have an accident in that city on any given day.

And, just like with you or me, there are circumstances that make accidents more likely. Imagine driving at night, in the fog or the rain; imagine driving in a new area, or even driving down an old familiar road, and suddenly there is a new construction zone. There are bird analogies for all of these events.

Birds can obviously see and avoid obstacles. When watching birds, you rarely see birds collide with objects. When driving, you can even watch them avoid your car with what sometimes appears to be a

Blackburnian Warbler during spring migration

startled expression. Some birds are good at this—you almost never see a dead swallow by the side of the road. Other birds are less good at avoiding obstacles. Sage Grouse are known for running into barb-wire fences. Let’s look at this in a little more detail using what is known about wind farms and bird behavior.

How many birds get killed?
Let’s start by looking at how many birds are actually killed at wind turbines. While birds do get killed, the numbers are in fact rather small. We don’t see thousands of birds dying at any turbine. We see an average of 2.8 birds killed per turbine† per year (calculated from data in NWCC 2010). For the statisticians out there, the plus or minus 2 standard errors is 2.1 to 3.5 birds/turbine/year.

Most of the birds killed are warblers, sparrows, and other small passerines (songbirds). Some are game birds such as pheasant. A few are raptors, waterfowl, or other species such as shorebirds, gulls, or egrets and cranes. The proportions of each type of birds killed are fairly constant across wind farms and regions (Morrison and Strickland 2008).

In 2003, with 4331 MW of installed wind power, bird mortalities were estimated to be about 9200 across the entire US (Erickson et al. 2005). This level of mortality is largely considered to be “insignificant” in the overall scheme. Most bird species can easily recover from a few hundred additional mortalities a year.

Mitigating factors—bird behavior
In fact, during migration when most birds are killed at wind farms, there are many millions of birds aloft. We don’t see most of them. Not only do we rarely look up, we are usually inside in our houses and cars shut off from the sky. Even when we do look up, we might not see the birds. Many of these birds migrate during at night when we are asleep or watching TV. Go outside and listen during the springtime and maybe you will hear the “tseep” of a warbler high overhead, or watch the full moon during fall and you will ever so occasionally see a bird fly across its surface, a silhouette against the moon.

Among the birds most heavily impacted at wind turbines are the night migrants, passerines such as the warblers and sparrows. Even these birds appear to avoid being struck by the turbines under most circumstances.

Many birds migrate so high you can’t see them. In fact, birds have been observed migrating as high as 30,000 feet up in the jet stream, and are occasionally a problem for airline traffic. These birds are so high that we usually don’t worry about them when siting wind farms (but see our comments under weather below).

Some birds, such as Whooping Cranes, fly along fairly narrow migration corridors and you won’t see them unless you are in the right place at the right time. In North Dakota, I once unexpectedly came upon two Whooping Cranes in an empty field—halfway between their wintering grounds in Aransas, TX and their breeding grounds in Canada. These giant but elegant birds danced a ballet—a bonding duet of spring.

So, just like humans, a few birds will have an “accident” while commuting. Birds occasionally run into buildings, light houses, and guy wires. I even had a bird run into me once. The harder an object is to see, the more likely they will run into it. The more an object looks like the background, or like a good path, the more likely they are to run into it. Windows and mirrored buildings are notorious for bird strikes (see BirdNotes 10 from Cornell Labs for more info on birds and windows).

Old-style wind turbines

Old-style wind turbines in California

Mostly, the night migrants fly well above turbine height. However, when it’s foggy or rainy, birds will fly much lower. This may cause a “double whammy” for the birds. Not only are they now flying within the rotor-swept height of the turbine, they may not be able to see as well and may have trouble orienting.

Even if birds can see the turbines, they may not avoid them. There is some evidence to suggest that birds don’t really pay much attention to visual cues during high-altitude migratory flights. Why should they? They evolved flying through relatively empty sky. In several million years there has never been a tree or a wall sticking up at 400 to 500 feet in the middle of the night sky. Imagine what you go through when you round a corner in your car and suddenly there is a tree in the road. Many of us take a second to register “Hey! That’s not supposed to be there!” before we apply our brakes.

Why do we care?
So, if so few birds are killed, why do we care? Why is it important to have biologists and regulators and non-profit organizations working so hard to “solve” this problem? You might ask, Is it really a problem?

For some, even if we can show that the impacts are low and unlikely to impact bird populations, it may still be a moral problem. People who care about life, who believe in the sanctity of all life, would prefer that no birds are killed at all. If some birds will inevitably be killed, they would prefer that every reasonable effort is made to minimize these deaths.

People who believe in the delicate balance of nature, or that humans do not fully understand the balance of nature, would also strongly argue for minimizing impacts. Our models and methods may be flawed, may not take into account subtle effects, or may not apply to this site at this time. While the large number of studies which show relatively consistent data are increasing biologists’ confidence, it is difficult to argue against this, as many technological advances in the past have had unanticipated impacts.

More turbines in California

Finally, while for many species biologists do not believe there will be significant impacts of any specific wind farm, there are potentially tens-of-thousands of wind farms (16 GW under one projection). The cumulative impacts—the impact of all these “small” effects added together—may have a large effect. The effect of all these wind turbines may add together incrementally or may have a “tipping point”; a point where suddenly the bird populations cannot overcome all of the insults; a point where the reproductive capacity is suddenly below the overall mortality levels. This point may vary by species or by group. In my next blog, I will talk about the different species and why impacts may matter more for some than for others, and which birds we may want to focus our conservation efforts.

(written by Caitlin Coberly 2011–Principle Ecologist at Merlin Ecological.  Please contact Caitlin at with questions or suggestions)

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Night migration and Acoustic Monitoring

computer set up

Dr. Coberly setting up computers for acoustic monitoring

Surprisingly, most bird species migrate at night.  This makes understanding and quantifying migration more difficult than pulling out your binoculars in spring and fall.  Several techniques have been developed to help understand night migration.  Each technique has it’s strengths and weaknesses.

Avian acoustic monitoring is a little-used technique in surveys for wind energy. In some situations, it can be very helpful.  Most birds can be identified to species using their night-migration calls. Acoustic monitoring can therefore be used to determine species composition during the night. It can also be useful in identifying night-migrating endangered species in an area. For example, some species may migrate through farmlands during the evening, but be completely absent during “normal” daytime survey hours. It is difficult to quantify risk for these species using standard point-count surveys.

Avian acoustic monitors are typically placed at ground level or slightly above (which helps reduce noise from insects).  Microphones can be directional or not, but in the “classic” set up (Evans 2003), a non-directional microphone is set up within a flower pot, resulting in a semi-directional effect.  Modern microphones can pick up most typical bird calls at around 300ft (this varies due to microphone, temperature, moisture, insect noise, and bird call volume). Turbine typically stand about 400 to 500ft, with the blade reaching to within 150ft of the ground, so the acoustic set-ups will pick up most but not all birds passing through the rotor swept area. Like most detectors, the area sampled is relatively conic, or cone-shaped, so the sample space is larger higher up.

As with many other passive detectors (such as acoustic bat monitors) neither the area sampled or the number of birds passing overhead are simple measures.  Birds with louder calls can be heard from further away, as can birds with a call pitch that more closely matches the optimum performance range of the microphone.

The number of bird calls is not a directly related to the number of birds.  Some birds call a lot, while others tend to remain relatively silent.  For example, terns are heard very infrequently during migration, while thrushes are the predominant group observed on the eastern seasboard during much of the fall migration. However, you can get an idea of the relative use by comparing the activity level of the same bird species in different areas.

Finally, while many birds can be identified to species using call notes, not all species can be identified yet.  Identifying birds by sight is a difficult enough skill to requires an experienced birder.  Some birders can identify birds by song.  Nighttime call notes, however, are of very short duration and can be very difficult to identify (anyone with experience trying to identify sparrows by “chip” notes can attest to this!).  Fortunately, Bill Evans and several people at Cornell Acoustic labs are making call data available to scientists.

At Merlin Ecological, we are currently conducting avian acoustic surveys to better understand neotropical warbler migration.  We hope to present our findings later in 2011.

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Post-construction surveys

We are adding K9 units to our post construction survey teams.  K9 units have been shown to have higher recovery rates and are much more efficient (Arnett 2006), resulting in better quality data for less time and money.   

Our dogs are specially bred for nose work.  And, while we were not surprised to have them point birds at an early age, we were surprised to find them naturally pointing bats!

Freckles, photo on right, is one of our up-and-coming pups.  She is in training using K9 search and rescue techniques, shown to be effective for human rescue, crime scene (cadaver), and police K9 work.  We are looking forward to getting Freckles out on site.  She is exceptionally high energy and LOVES to work.

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