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Archive for the ‘Owls’ Category

Information is important. With information each of us as individuals, and our society as a whole, can learn about the world. With information, we can all make decisions that make sense. With information, we can all discuss ideas.

Without information none of that is possible. Without information, we are, at best, at the mercy of our current, limited knowledge, and our base instincts. Without information we are, at worst, at the mercy of the limited knowledge and instincts of someone else.

This is why the gag order, and insistence that all reports and data be pre-screened before release to the public, issued by the President to the EPA are so concerning to me, and I think should be so concerning everyone else. This is exactly the kind of action that limits access to, and spread of, information. It will only hamper all of our abilities to operate as rational, critically thinking individuals. It is the kind of action that is put in place to control what we, as citizens, know and when we know it. This is censorship and it has no place in science or a free society.

#thisisnotnormal

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I have written about the conflict between Spotted Owls (Strix occidentalis) and Barred Owls (Strix varia) a couple of times before (here and here). The basic situation is that Barred Owls (generally native to eastern North America) have been expanding their range into the range of the Spotted Owl (western North America) for the past 40 years or so. The Spotted Owl has been declining for a long time and two of the three subspecies are federally listed as Threatened under the U.S. Endangered Species Act. The intrusion of Barred Owls is now a big problem for the Spotted Owls for several reasons.

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A subadult Spotted Owl (photo by USF&WS)

One reason is that the total Spotted Owl population is smaller than the total Barred Owl Population, and small populations are more at risk of declines and extinction. Another reasons is that the Barred Owls are bigger and more aggressive than Spotted Owls and push the Spotted Owls out of nesting territories. Sometimes the Barred Owls are big enough and aggressive enough that they eat the Spotted Owl. Yet another issue is that the two species of owl are so closely related that they can hybridize and produce so called Sparred Owls. This genetic mixing has much more profound implications for the long term persistence of the Spotted Owl than the Barred Owl due the much smaller population size of the the former.

The primary solution that has been proposed to save the Spotted Owl from extinction has been to alter logging practices and set aside the old-growth forests that the Spotted Owls depend on. However, this has not been enough to halt the Spotted Owl decline. An additional plan that the U.S. Fish & Wildlife Service has been pursuing is the lethal removal of Barred Owls from areas where Spotted Owls are nesting or have nested in the recent past. From 2009 to 2013, USF&WS scientists killed approximately 90 Barred Owls. This had a marked effect on the Spotted Owl population. In areas where Barred Owls were removed, Spotted Owl population levels did not change any more than in areas where Barred Owls had never been observed. Also, territories that were held by the removed Barred Owls were fairly quickly re-occupied by Spotted Owls.

This result is a surprise to me. In my past posts, I was quite critical of the plan, and was skeptical that the removal of Barred Owls would actually benefit Spotted Owls. The results of the removal study suggest that this strategy might work to preserve Spotted Owls. But there are still problems.

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An adult Barred Owl (photo by Ashley Hockenberry)

Spotted Owls respond well to the removal of their Barred Owl competitors. But how will these removals be maintained? Shooting Barred Owls takes a fairly considerable effort, so there is no way that this process can be enacted over the whole range of the Spotted Owl. It will not be possible to even do it over large areas. Instead, the only way that this plan will be able to be put into practice will be on very small areas of core Spotted Owl habitat. The other problem is one of time. To be effective, these core areas will have to be patrolled regularly, forever. New Barred Owls are perfectly capable of re-invading areas where the earlier Barred Owl inhabitants had been shot, and they will do so in short order.

So, much of my skepticism and critiques from my earlier posts still stand. I do not think that killing Barred Owls is a long-term solution for Spotted Owls on really any scale that will be useful for the survival of the species. It will simply require more time, effort, and money than anyone has to devote to the issue. That having been said, the fact that killing Barred Owls made any impact on Spotted Owls at all is more than I thought would happen.

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It has been 14 years since the first printing of the first edition of David Allen Sibley’s Sibley Guide to Birds. It was a wonderful book and stood out, at least in my mind, as the best guide to come out since Roger Tory Peterson’s guides to eastern and western birds. Now Sibley has produced his second edition, my copy just arrived in the mail yesterday. And this new edition has a lot of changes from he old one.

The first thing that struck me were the colors. This new edition has generally bolder, darker, richer colors than the first edition. This change may serve to highlight plumage characteristics and draw attention to color contrasts, and so may make the guide more user friendly. However, there is always a danger when attempting to improve on reality and the result will be distorting reality. Overall, I really like the richer colors, but I do think that on some of the birds, such as the California Towhee, it may have gone a bit too far.

A second major change is that the families of birds now appear in a very different order. Traditionally, bird guides have been formatted so that they present the groups of birds in an order that follows the evolutionary history of birds. In most guides this has meant that the first groups are the Loons then the Grebes then the Albatross and Petrels. However, with ever more detailed and accurate DNA sequencing abilities, the evolutionary history of birds has been going through several rounds of shake-ups, and Sibley’s second edition reflects the more current understanding of how birds have evolved. Now, the first groups shown are the Ducks and Geese followed by the Gallinacious birds and then the Loons, and the altered order of bird families continues throughout the rest of the book. I really like that the order of bird families has been changed. It means that we all have a better understanding of evolution. I am sure that some people will be annoyed at the new ordering, and may feel a bit disoriented when having to re-learn where to find a particular group of birds, but our knowledge is always changing, and the resources we use should reflect those changes.

A third big change is the addition of 111 rare species. These are species that are generally found on other continents, and that have been recorded a very small number of times in North America. At first, I thought that this would simply clutter up the guide with a bunch of birds that basically no one sees, and that they would distract from the birds that people are generally looking for when they open their bird books. But, on further reflection, I have actually really like having all these new birds. It gives us all a better understanding of, and exposure to, what birds are out there. I think that if we as birders, all have a more global understanding of our favorite taxa, that can lead to nothing but good.

One very minor bone to pick is something that was pointed out to me by the late, great Rich Stallcup. He noticed that the Wrentit had a somewhat worried expression and that this was not really representative of the fierce Wrentit spirit. In the new edition, the Wrentit still looks worried.

So, overall, I really like the new Sibley Guide to Birds a great deal and am looking forward to my next opportunity to use it. If I find a White-crested Elaenia I will now be able to identify it!

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Spotted Owls have lots of big problems.  One is that their stands of old growth forests are dwindling due to the expansion of human development.  Another is the growing threat of catastrophic wildfires destroying what habitat has not been converted to human uses.  These two issues resulted in two of the subspecies of Spotted Owl being listed as federally threatened under the Endangered Species Act and the third to be listed as a Species of Special Concern.  But the Spotted Owl actually has a problem that is even bigger than those two.  It is the Barred Owl.  I have written previously about the conflict between Spotted Owl and Barred Owls (https://abirdingnaturalist.wordpress.com/2012/08/17/spotted-owl-vs-barred-owl/).  The basic problem is that Barred Owls are expanding their range westward into the range of the Spotted Owl.  Barred Owls are bigger and more aggressive than Spotted Owls, so when they compete for territories the Spotted Owls are driven out or even eaten.  And if the Spotted Owl is not deprived of the territory or eaten, Barred Owls sometimes breed with Spotted Owls, so they are losing their genetic uniqueness as well.

This is a developing situation that wildlife managers, ornithologists and birders have been watching since the 1960s, and there has been a lot of discussion on what, if anything, to do.  Ideas ranging anywhere from doing nothing to going out and shooting Barred Owls have been put on the table.  The idea of shooting Barred Owls started in 2009 when the US Fish and Wildlife Service first proposed the idea and started asking for public comment on it.  The idea was to send hunters out into areas that were known to have good populations of Spotted Owls.  If a Barred Owl was detected, the hunters would use recordings to attract the Barred Owl and shoot it.  There was a fair bit of public commenting on this idea, some for and some against, and then the idea dropped off the radar for most people. Well, just recently, there has been a new development.  The US Fish and Wildlife Service is going ahead with the plan to shoot Barred Owls.  They are proposing a four year trial period beginning in 2013.  During this period, each fall (the non-breeding season) hunters will be sent out into four areas, two in Washington, one in Oregon, and one is California.  The goal will be to kill 3,603 Barred Owls, and then see if Spotted Owl numbers increase.  Why 3,603 specifically?  I have no idea.

I have several problems with this plan, but let me get one issue that I do not have a problem with out the way first.  I am not, categorically, against killing Barred Owls.  I eat meat, I am even a hunter, so it is not the killing of animals that I take issue with.  I am sure that others do feel that it is somehow morally wrong to kill an owl, any owl, but that is not me.  From a population biology standpoint, the Barred Owl is doing really well as a species and so there is no danger at all of the species as a whole being damaged by some birds being killed.  Far more than 3,000 die each year due to starvation, disease, exposure to the elements, or flying into cars or buildings or antennas.

No, my biggest problem with this plan is that it is not going to work.  The Barred Owl population has been increasing in number and expanding in range pretty darn fast.  To think that killing a few is going to make any kind of difference is like thinking that if you beat at the ocean with a garden rake, you will be able to hold back the tide.  Every owl that is killed will be replaced by another from the expanding population.  To top that off, this four year trial is going to cost around 3 million dollars.  A much better use of that money would be to purchase 3 million dollars of land and set it aside as protected wilderness.  This trial will also waste a lot of personnel hours that, just like the money, could be much better spent elsewhere.  And that is just the money and personnel hours for the trial.

An even if this trial run is a success and does lead to a decrease in Barred Owl numbers and an increase in Spotted Owl numbers, this plan will still not work.  The only way that lethal removal works is if you kill  large number of individuals in a given area, and then keep doing it every year.  The constant level of effort that this would require for hunting Barred Owls is simply not sustainable.  To protect the Spotted Owl it would be necessary to remove Barred Owls from all, or most, of the Spotted Owl breeding areas (not just the four limited regions in the trial) and to continue doing so forever (since the moment the hunters stop, more Barred Owls will enter the protected areas).  This would require vastly more time and money than anyone is actually going to have.

 

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My first memory of Rich Stallcup is actually not a bird memory at all, but rather a frog memory.  I was probably about ten years old when my mother, brother and I joined him on a bird walk.  But the very first thing he stopped to show the group were several Bullfrogs.  He got his scope on them and let us watch them breath.  He told us about how they were an invasive species and voracious predators that were eating the tadpoles and larva of other animals and so driving down their populations.  My second memory of Rich is a bird memory.  We went on a bird walk to Limantour Beach that Rich was leading that focused on gull identification.  I remember standing looking at a large flock of gulls and listening to him point out the subtle differences between different species, and the even more subtle differences between different aged birds of the same species.  I remember being amazed at the level of detail that he could notice and even more amazed by the concept that there was so much more detail out there to be noticed then I had ever realized before.

These memories, and so many more, point out what I feel were some of Rich’s greatest qualities.  He was a naturalist in the truest sense of the word.  He was the best birder I have ever known with an encyclopedic knowledge of birds, but he also knew tremendous amounts about mammals, reptiles, butterflies, and dragonflies.  He even kept a wildflower life list.  In an age of ever increasing specialization on smaller and smaller scales of knowledge, Rich went the other way and proved that a person does not have to choose between being a jack of all trades or a master of just one, but instead could master quite a few.  It is a lesson that I have tried to learn and an ideal that I continue to strive for.  And his attention to detail was incredible.  While standing watching a group of Bushtits work their way through a willow stand, he finally decided that he was not missing any other birds in the flock when he started recognizing individual Bushtits in the flock!

Of course, Rich’s professional accolades are many.  One of the prominent discoverers of the amazing natural history of Point Reyes and the fact that the outer point acts as a tremendous vagrant trap attracting unusual birds from across the continent when they are disoriented by a predator attack or a storm.  The outer point now also attracts birders from around the world.  Rich was also one of the founders of the Point Reyes Bird Observatory, an organization that is now one of the foremost international conservation NGOs.  He has written books, papers, and articles; and also led countless bird walks and pelagic birding trips, all with the aim of introducing people to nature.

I had the good fortune to be able to bird with Rich for many years.  When he and Ellen Blustein started the PRBO Youth Bird-a-thon Team in 1999, the four founding youth members were myself, my brother,and two of my best friends.  I have continued to participate in that event ever since.  Even after I got old enough that I could not count as a youth anymore, Rich seemed happy to have me stay on as a mentor to the incoming generations of youths.  When he learned that I was expecting my first child he told me that, as long as the kid was more than two days old, I should bring him or her on the Point Reyes Christmas Bird Count!  I was very happy that he was able to meet my wife a couple of times, and saddened that my child will never get the chance.

Rich Stallcup died on the 15th of December, 2012 of Leukemia.  His loved ones were at this side.  He was a naturalist who inspired me and many others with his knowledge, passion and generosity, and he will be greatly missed.

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The Broad-winged Hawk (Buteo platypterus) is one of North America’s smaller Buteos being about two thirds the size of a Red-tailed Hawk.  It is common and wide spread in the eastern half North America with an estimated breeding population of at least 1.7 million individuals.  It breeds throughout deciduous and mixed conifer-deciduous forests and hunts mostly small mammals and reptiles, but also includes the occasional bird, amphibian, or even more occasional insect.  Breeding densities have been estimated to range from 1 pair every 2 to 5 square kilometers.  However, breeding bird surveys appear to be inadequate at detecting Broad-winged Hawks do to how secretive they are when on their nesting territory.  Migration has proved to be a better point in their annual cycle to monitor population levels.

Along with the Swainson’s Hawk (Buteo swainsoni), the Broad-winged Hawk is one of the raptor species that migrates the longest distances between its breeding grounds and non-breeding grounds which stretch from Mexico to Brazil.  As might be expected from the combination of how common they are and this long migration distance, this species is a very common member of fall hawkwatch counts in the eastern USA and in Central America.  Numbers in the 10s of thousands are not unusual at many sites (such as Hawk Mountain PA) and several sites have counts of 100s of thousands (such as Corpus Cristi, TX) and even over 1 million (such as Vera Cruz, MX).  It is unusual for a raptor in that groups of these birds migrate in flocks frequently forming large kettles that fill the sky as they move south.  But these are all eastern sites.  Do Broad-winged Hawk occur in the western half of the continent?

Before the 1980s the answer would have generally been no, but during the 1980s something started to change.  Sightings during migration have been increasing in many western states including Idaho, Montana, Wyoming, Colorado, New Mexico, and Arizona.  This suggests that the breeding range of the Broad-winged Hawk is extending to the west into Alberta and British Columbia.  The Golden Gate Raptor Observatory (GGRO) in California have been seeing them regularly since that fall migration was first discovered in 1972.  It remains the best place to spot a Broad-winged hawk west of the Rocky Mountains.  This year was an amazing Broad-winged year at the GGRO.  Most fall seasons see between 25 and 240 Broad-winged Hawks with numbers generally concentrated in the last half of September.  But during the 2012 season (and only through the end of November, since the count season is still ongoing) hawkwatchers have counted a record-shattering  755 Broad-winged Hawks!  This total included one day which recorded a total of 295 which is higher than the previous record season total of 248!  No one is completely sure what caused this boom of Broad-wings, but one interesting facet is that of the 755 birds seen this year, about 99% of them were hatch-year birds.  This indicates that the population of Broad-winged Hawks that breed in western Canada had a very good year this past spring and summer.

The western expansion of the Broad-winged Hawk breeding range roughly matches the westward movement of the Barred Owl (Strix varia).  It also roughly matches the eastern expansion of the Evening Grosbeak (Coccothraustes vespertinus) across the same geographic area of Canada, although the Evening Grosbeaks moved east earlier than the hawk or owl moved west.  All three of these species prosper in mixed deciduous-conifer forests, and that hints at a possible explanation.  These range expansions could be the result of increasing edge habitat that results from timber harvesting in areas of what would otherwise be wide swaths of coniferous forest.  They could also be due to the increased numbers of trees that are being planted in and around cities in the great plains of Canada and the USA as wind-breaks.  Such human-induced changes to the landscape will no doubt cause changes to the distributions of other organisms, and these three species may be examples.  More investigation into these changes in range are needed before any convincing explanation is reached.

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The day before yesterday, I was walking along the edge of Lake Washington, which is very close to our new home in West Sacramento, CA.  It was a great morning of birding with several of the early fall migrating Wilson’s Warblers, an adult Red-shouldered Hawk, a Lesser Scaup feeding on the lake and about 300 Long-billed Dowitchers resting on one muddy portion of shore.

As I walked around a bend in the cattails and tules, I saw a female American Kestrel swooping and diving back and forth at the top of an oak tree.  She was also screaming like crazy.  Nearby, perched on a bare branch of a sapling was a male American Kestrel.  He was calling like crazy as well!  As I stood there, I also heard several Western Scrub Jays also making a loud ruckus in the tree.  I was certainly curious to see what was causing all this fuss.  I walked closer, and as I did so, a Red-tailed Hawk flew past.  As it neared the tree it dipped low and dropped its legs down to strafe the tree top!  As I got even closer, two Anna’s Hummingbirds joined in to start darting in and out of the tree top at whatever was there.  What could cause this much commotion and attract this much ferocious attention from so many very different species?  I got my answer a few moments later when a Great Horned Owl launched itself out of the tree top and flew towards a different group of tree some distance away.  After the owl left, most of the birds seemed to calm down, expect for the American Kestrels which both followed the owl to its new perch site and continued to berate it there.

Not only was the commotion quite impressive, it was interesting how all these different species, with their very diverse natural histories, would all feel threatened by one owl!

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