Posts Tagged ‘Evening Grosbeak’


I spent the 4th of July weekend camping with my family at one of my favorite spots. Domingo Spring in Lassen National Forest. I first visited this site during my graduate school work where I was recording the calls of Evening Grosbeaks, and I have returned regularly ever since. The campground, set among jumbled piles of volcanic rocks and large conifer trees, is immediately beside a wet meadow that Domingo Creek runs through. Near the entrance of the campground is the source of Domingo Creek, and the campground’s namesake, Domingo Spring. This spring is one of the few places I know of where one can drink right out of the land. In my mind, that makes this a very special spot, indeed. We also drove to Willow Lake for part of one day which was lovely. Willow Lake has a floating sphagnum bog where a couple of native species of carnivorous plants grow wild.


My brother birding Domingo Spring

The days we spent camping were filled with birds, a lake visit, walks throughout the surrounding meadows, lots of cooking over the fire, singing, talking politics, reading the Declaration of Independence on the 4th of July, drawing, and so much more! One bird encounter that was really wonderful was our neighbors in the campground. A pair of Cassin’s Vireos had a nest about 25 feet up a ponderosa pine tree at the edge of our campsite where four nestlings eagerly gobbled down each of the insects their parents delivered. Many Western Tanagers, including a lot of newly fledged birds, were also around this year.

The full species list for birds included: Mallard, Common Nighthawk, Anna’s Hummingbird, Turkey Vulture, Great Horned Owl, Black-backed Woodpecker, Hairy Woodpecker, White-headed Woodpecker, Pileated Woodpecker, Northern Flicker, Western Wood-Pewee, Stellar’s Jay, Common Raven, Tree Swallow, Mountain Chickadee, Red-breasted Nuthatch, Brown Creeper, House Wren, American Robin, Cassin’s Vireo, Evening Grosbeak, Purple Finch, Cassin’s Finch, Song Sparrow, Lincoln’s Sparrow, Red-winged Blackbird, Orange-crowned Warbler, MacGillivray’s Warbler, and Western Tanager.


My daughter holding a Pacific Tree Frog

We also had some nice herpetological encounters. I caught a small Mountain Gartersnake, and my wife and daughter caught a Pacific Tree Frog. Oddly, we did not see any gartersnakes are Willow Lake. In the past we have often seen them swimming in the lake as they hunt for minnows in the water, sometimes around our feet. This year, the water was much more turbid that it usually is (a result of the fairly recent snow melt?), and maybe this made the water less appealing as hunting grounds for the snakes that are pretty visual predators.

Mountain Gartersnake - Domingo Spring - 20190705

Mountain Gartersnake

Mammals we saw included Mule Deer, California Groundsquirrel, Golden-mantled Groundsquirrel, Douglas Squirrel, and Allen’s Chipmunk.

I very much look forward to the next time I return to Domingo Spring to enjoy the mountains and drink from the rocks.




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Yesterday, I was up in the mountains for my last field day of the year. I spent a few hours in Truckee, CA and after not getting a lot of Evening Grosbeak action, I headed to Soda Springs, CA. Not much going on their either, so it was not a particularly strong finish, but it is always nice to be in the wilds. Just how nice it is to spend regular time in wilderness got me thinking about next year. I am not planning on having field work next year, as I will be working on other projects, and I am really gong to miss my regular mountain visits. I have been spending one day a week, almost every week, in the Sierra for the last two summers and falls. I have seen some beautiful locations and had the opportunity to get to know several areas at a very detailed level. It has been wonderful to feel like I am genuinely getting better at knowing the birds up there by sight and sound. To get more comfortable with a biological community like this has been a really special treat, for me.

I am not sure what I am going to do to fill that gap next year. My research projects are probably going to keep me pretty close to home most of the time. I have already started exploring my local area in more detail, which has been fun and which I will certainly continue to do. But birding in the Sacramento area is just not wild like the Sierra. There is nothing close to me that is. Well, we will see what happens.

I can say that these past two summers have been fairly successful. I have collected enough data for what should become one chapter of my dissertation! I am now going to get to work analyzing the data, writing the paper, and getting it published. That is going to be fun. But it will certainly be good to have this section of my work finished. Feeling like I am accomplishing steps towards my degree is something I have been lacking recently, and getting this out the door will be a big step in the right direction. I will certainly post updates as that process occurs!

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A few days ago, I found myself in Blackwood Canyon on the west coast of Lake Tahoe. It is a beautiful spot where Evening Grosbeaks have been reported regularly over the last couple of weeks. The day was lovely, and the birding was terrific with lots of classic mountain birds all around. Warbling Vireos and Hermit Warblers were foraging in the poplars that grow along side the stream that runs down the middle of the canyon. MacGillivray’s and Wilson’s Warblers were leading young birds around through the willows. Spotted Sandpipers were walking and bobbing their tails as they foraged along the rocky stream edges. Female Mallards lead broods of ducklings from pool to pool.

I did find a flock of Evening Grosbeaks, though they were not particularly cooperative in terms of my research plans. However, while I did not get the experimental trials I had hoped for accomplished, I did see something new and cool. I was stopped along the side of a road at around 9:30am beside a small group of spruce tree when I heard an Evening Grosbeak giving really loud flight calls. They were actually kind of spectacularly loud! As I watched, I saw the grosbeak, a male, flying from tree top to tree top and continuing to give these high amplitude calls. After standing below him recording for a few minutes, I figured out why he was behaving this way. There was an adult Red-tailed Hawk perched in the top of one of the spruce trees and the grosbeak was mobbing it. Now, Evening Grosbeaks are known to use their flight calls to coordinate the movement of a flock and they are also used by birds to locate other individuals over long distances. Further, they may possibly play a role in mate choice decisions and in population identification. However, to the best of my knowledge, this is the first time flight call have been observed being used in a predator harassment context! After a few more minutes, the Red-tailed Hawk flew off. The Evening Grosbeak, having succeeded in annoying the predator into leaving, quieted down and then departed on his own business.

This was yet another reminder that calls can have many different functions even when it is basically the same call, and even when that call is has a fairly simple structure. What subtle differences communicate different information to a receiver? Was the volume of these calls an important component of harassing a predator? Are there other differences (speed of delivery, frequency range, something else) between flight calls that are used in different contexts? I have this one recording, and so will certainly examine it to see if there is anything that jumps out at me, but with only the one occurrence, it will be hard to identify smaller differences, even though such small differences may be quite important to the birds involved. This also served as a reminder that exciting things can happen, but you have to spend time out with your study subjects to see them!

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This week I began my summer field season. I am planning weekly excursions up into, and throughout, the Sierra Nevada mountains to find Evening Grosbeaks, my study species. My first day in the field was a modest start. I left West Sacramento at 3:00am and drove up highway CA-49 to the San Francisco State Field Campus just outside of the tiny town of Bassetts, CA. When I arrived, at around 6:00, it was lightly misty and on the cold side. I walked around the field camp a little and heard the forest wake up. It was not long before I heard my first Evening Grosbeak of the day and setup my equipment. As the weather cleared, I got some work done testing how Evening Grosbeaks respond to recordings of various kinds, but there were not that many grosbeaks around. There were a bunch of other birds around that gave me some great looks, including several near collisions. At various points in the morning, I was nearly hit in the head by a Western Tanager, a Red-breasted Sapsucker, a White-headed Woodpecker, and a Mountain Chickadee! I also got to see an Osprey circling high overhead with its breakfast, a moderate sized fish, in its talons. But, since the grosbeaks were not especially cooperative I decided to try a new spot. I continued east on CA-49 to Yuba Pass where I was happy to find more grosbeaks along with a few Red Crossbills, lots of Cassin’s Finches, and several Chipping Sparrows, one of which landed on the side of the road not five feet from me and sang and sang. Delightful! After a while, and grosbeaks only showing up few and far between, I headed back down towards Bassetts where I saw Townsend’s Solitaire, which were a real treat for me, and a very lovely pair of Fox Sparrows. Then, after a brief stop in at the Sierra Skies RV Park in Sierra City, I was homeward bound. Odd as it sounds, the RV park in Sierra City was a great field site for me during my Master’s work. All in all, it was great to get out into the field and shake the dust off my methodology. I only got 5 actual trials, and since I am aiming for 10 each day, that was a bit lower than I would like. But there is a lot of summer ahead, so the work will get done. Next week I am planning on heading to the area around Quincy, CA and Bucks Lake to poke around, and hopefully fine more Evening Grosbeaks who will listen to my recordings and let me know what they think of them!

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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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One facet of my research on the Evening Grosbeak (Coccothraustes vespertinus) that I am hoping to put together is a much better survey of where the different flight call types occur, what they are doing, and what they are eating.  To give a bit of background, five different variants of Evening Grosbeak flight call have been observed.  These different variants have been labeled Type 1 through Type 5, and while the differences are subtle to the human ear, they are distinct enough that with practice they can be identified in the field.  They are also different enough that the grosbeaks themselves can almost certainly tell them apart as well, and so may play an important role in group membership identification.

The geographic ranges of birds that make these different flight call types has been generally worked out.  Type 1 is found mostly in the Pacific northwest and central Rocky Mountains, Type 2 is mostly found in the Sierra Nevada and southern Cascade Mountains of California and Oregon, Type 3 is mostly found around Great Lakes and in New England and southeast Canada, Type 4 is mostly found in the southern Rocky Mountains of Colorado and New Mexico, and Type 5 is mostly found in the mountains of central Mexico and southern Arizona.  I say mostly a lot in that description because there is a lot that we don’t know.  It is known that there is a fair bit of overlap in where the different flight call types have been observed.  In the Sierra, while most of the birds give Type 2 flight calls there are birds that give Type 1 flight call as well.  In Wyoming, where Type 1 would be expected, Type 1 birds are the most commonly observed, but Type 4 birds occur there in smaller numbers as well.  There are also parts of the continent where it is not well understood what type might be the most common.  The area in central Canada that is between Type 1 and Type 3 is filled with question marks.  Nevada and Utah are between the Type 1, Type 2 and Type 4 regions.  This area does not have a lot of Evening Grosbeak habitat, but it seems likely that these birds do occur on high mountain ridges.  They may or may not breed there, but even knowing what birds pass through the area would be interesting.  Another huge area of unknowns surrounds Type 5.  Very little research has been done on where these birds occur, exactly.  Even the portion of the range that is in the USA in Arizona and possibly New Mexico is not well established.

An even less understood aspect of Evening Grosbeak life is that of diet.  Most bird books give the very general “eats seeds and insects” with little or no explanation of what seeds and what insects.  Do birds that make different flight call types eat different foods in their respective different ranges?  No one knows.  When individuals that produce different flight call types find themselves in the same place, do they then retain any differences in diet, or do they all simply eat whatever is around?  Again, no one knows.

So here is my call for aid.  I want to collect information on the calls and diet of Evening Grosbeaks across North America.  This will take a very long time if I do it all myself, but I am hoping that you might be willing to help.  If you are willing to help there are two ways you can.  One is if you see Evening Grosbeaks any where, take a moment to observe what they are eating.  What I am looking for is information on what these birds are eating in the wild, so bird seed out of a feeder may not give the most interesting information, although you never know.  The second way to contribute is if you hear an Evening Grosbeak vocalizing.  If you do, and have any recording device (this does not have to be fancy, I have gotten useful recordings off the recorders in digital cameras), then make a recording.  These recordings will be best if they have the vocalizations of only one bird calling for as long as possible, but any recording will be useful and this includes birds at feeders.  After you have made an observation or recording make a note of the date, time of day, location (be as exact as possible.  GPS locations would be great), and any notes on behavior or habitat that seems interesting to you.  Then send them along to me at anhaiman@ucdavis.edu

This is going to be a long and slow accumulation of knowledge which is why I am starting now.  I will be collecting this information for years.  As you find birds and can pass the information along to me, don’t worry about being too late.  Thanks in advance!

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Some species of birds are residents that remain in the same place all year long.  Other species migrate from breeding grounds to wintering grounds and back again.  Of these migrants, some are latitudinal migrants that move from north to south and then south to north, and others are altitudinal migrants that move down-slope in winter to avoid harsh conditions higher up, and then move up-slope in summer to take advantage of the short, but intense, mountain growing season.  Many species have a mix of both resident populations that occur at lower latitudes or altitudes staying put, and other populations of the same species that are migratory and occur at higher latitudes or altitudes which move to warmer areas when they have to.  Some species are nomads that wander across a landscape in search of food with no reliable annual pattern.  And then there are the irruptive species that respond to food and/or weather conditions and can move far outside their usual geographic ranges in order to avoid poor conditions and enjoy favorable conditions.

These irruptive species generally belong to one of the other types of movement groups.  Snowy Owls, for example, are usually residents except for when food is scarce when they can move south quite far into the lower 48 states.  No one is sure why some species are irruptive and other are not; they are scattered across many different bird families, and have all kinds of different natural histories.  Irruptions certainly do not occur every year, and even when they do occur, they can be of different magnitudes, but if they are going to occur it is fall and winter because if food is going to run out, that is when it will happen.  This year we seem to be having a bit of a Red-breasted Nuthatch irruption in the Davis area.  Last year we had only a few of these birds hanging around the Davis area in winter, but now they are of lots of them in Davis and West Sacramento as well.  From what I saw last weekend while visiting my mom in Berkeley, they are having a bit of a Pine Siskin irruption there.  She had a flock of at least 25 birds constantly swarming over her feeders where as I have seen years when there were few to none to none at all in Berkeley.  Last winter we have a significant Evening Grosbeak irruption which was quite unusual.  Since I am studying this species, I got sent a number of recordings of the flight calls that these irruptive birds were making.  Interestingly, the birds that were showing up in the central valley or on the central coast of California were not making the Type 2 flight call that is most commonly found in Sierra Nevada (which is the closest population).  Instead, they all seemed to be making Type 1 flight calls which is generally found in the Pacific Northwest and the central Rockey Mountains!

Tracking these irruptions is not only exciting, but it may be able to tell us about the stability of the habitats that the birds come from.  In this time of rapid global climate change, understanding which habitats are remaining relatively stable and which are not could be very important in bird conservation.

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This past weekend, my wife and I joined the rest of the graduate group that I am in for our annual retreat.  The retreat was a camping trip to Boca Spring campground.  It is a great campground in the eastern Sierra Nevada between Truckee and the Nevada State boarder at about 5900 ft in elevation, and set amongst Ponderosa Pines and the occasional Lodgepole Pine.  Each morning I got up early and went out to do some birding!  On Saturday morning, I walked along forest service roads through the pines and around the edges of wet mountain meadows amidst the sagebrush.  It was simply lovely.  And there was some great birding to be had!  At one point, I heard a Northern Pygmy Owl tooting away not far from me, though I was never able to actually see it.  On a small ridge line, I found a mixed flick that included Mountain Chickadee, Yellow-rumped Warbler, White-breasted Nuthatch, Red-breasted Nuthatch, and Pygmy Nuthatch.  From what I can remember, this is only the second or third time I have had a three nuthatch species day!  I was quite thrilled!  This flock was moving through the forest along the ridge.  What really struck me was how unevenly the birds were scattered across the forest.  I had found this fair sized flock of birds all in one place, but before and after, walked through forest that looked the same to me and had the same topography, but had no such flocks.  What made that particular small ridge-line so much better than the one to the east or west of it?  On my way back to camp, I got an additional thrill when I heard, and then saw, Evening Grosbeaks in the area!  Back in the campground, there were White-headed Woodpeckers and a small flock of Western Bluebirds.  Also back in camp, a group of Evening Grosbeaks flew right into the trees above us.  There were about eight birds and all the flight calls that I heard were Type 2, which is the dominant Sierra type.
In the afternoon, we visited the Sagehen Creek Reserve.  This is one of the nature reserves run by the University of California.  We were joined by my advisor who gave us a introductory presentation on the birds and habitat of the high Sierra, and then we all went for a walk to see what we could see.  I added Red Crossbill, Pine Siskin, Hairy Woodpecker, and MacGillivray’s Warbler.  We also found an adult Caddisfly.  Not sure of what species, but I am sure that is this first adult caddisfly I have ever seen!  We also found a Comma which is a species of butterfly.

This was a great trip with great birds and other wildlife, and I even got some scouting done for my own research!  I will definitely be returning to the Boca Spring Campground in the future to find my Evening Grosbeaks.

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I have been studying the Evening Grosbeak for the past three years for first my Master’s degree and now my Ph.D.  Studying this species has had many wonderful benefits.  Since they are commonly found in mountainous areas, I have traveled to, and camped in, many parts of the Sierra Nevada, Cascade, and Rocky Mountains.  I have met wonderfully generous people interested in the birds that share this world with us.  I have had the opportunity to glimpse some of the details of some aspects of the lives that members of this species lead.  However, one facet of working with this species that has not been quite so wonderful is the bite that these birds can deliver!  It is amazingly powerful!  I have been banding birds of many species for over a decade now, and in that time I have been bitten by quite a few birds.  I have been bitten by Cardinals, I have been bitten by American Kestrels, and I have bitten by Downy Woodpeckers just to name a few of the more painful species.  I have even been bitten by Black-headed and Blue Grosbeaks, which have a similarly shaped beak, though they are not actually closely related to the Evening Grosbeak.  None of those bites prepared me for the first time I was bitten by an Evening Grosbeak.  I was in Oregon on my first trip out to do field work on my project and had caught my first Evening Grosbeak in my mist net.  I was very excited and began spreading the net open so that I could untangle the bird.  Just as I was reaching my hand in to get a hold of the bird, it suddenly turned its head and clamped its beak down on my finger.  Wow, did it hurt!  If you take a pair of pliers, put the side of one of your fingers between the jaws, and squeeze tight, you will have some idea of what my finger was feeling at this point.  And not only do they have the strength to cause some serious pain, but they have the stamina to continue applying that crushing pressure seemingly indefinitely!  I reached my other hand in and tried to pull the bird away from my hand, but it would not let go.  I waved my other hand around near its head, which sometimes works to distract a bird, but it would not let go.  My eyes now watering from the pain, I even tried to pry the birds’ beak off of me with my other hand, but it would not let go!  Finally, it seemed to grow bored with my finger and let go and started screaming at me instead.  Over the next two days, I caught about 30 Evening Grosbeaks and many of them treated me to the same amazing bite!  By the end of my trip the sides of several of my fingers were black-and-blue with bruises from the repeated biting.

To give you a reference for what Evening Grosbeaks use their beaks for when they are not biting banders, they can sometimes be seen eating Chokecherry (Prunus virginiana) or Bitter Cherry (Prunus emarginata).  Like domestic cherry we all buy in the grocery store, these wild cherries have a very hard pit surrounded by a layer of soft fleshy meat.  Evening Grosbeaks carefully peel off the fleshy meat and then drop it on the ground.  They then take the hard pit in their beaks and crack it open to eat the tissue inside!  No wonder my fingers hurt!

Finding this our for my self, and watching others who have worked with me find it out for themselves, has actually been a very exciting process.  The only way to learn about a thing is to get close to it.  Sometimes this may mean closer than is comfortable, but it is only through this closeness, this intimacy, that true understanding is gained.  As my research on these birds continues, I am looking forward to learning many more little facts about them, and so to coming ever closer to true understanding.

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Each year, the American Birding Association (ABA) selects a particular species as its Bird of the Year.  The species is selected based on a combination of character of the bird itself, how it related to birders, and how it can serve as a symbol for the birding community.  This year, the ABA Bird of the Year is the Evening Grosbeaks, and as I have been studying Evening Grosbeaks for the past three years, I was especially excited by this choice.  I figured the added attention on this species might lead people be curious to know about them and their biology, and so here is a bit of information on them.

Evening Grosbeaks are a fascinating species for many reasons.  One of these reasons, and the one that first caught my attention, is that there have been so few studies done.  For being so common a visitor to backyard bird feeders, especially in winter, I was amazed at how little was known about these beautiful birds.  Do Evening Grosbeaks have a song?  What do the courtship rituals involve?  How many subspecies exist?  Where do birds go to throughout the year?  How do birds find food sources?  All of these are big unknowns for the Evening Grosbeak, and that intrigues me.

But before we get into more of the unknown, here is some of what is known about this bird.  It belongs to a group called the Cardueline Finches.  This group includes such species as House, Cassin’s and Purple Finches; Pine Grosbeak; the Goldfinches; the Crossbills; the Redpolls; and all the Siskins.  This group is found across North and South America and Eurasia.  Many of these species do not have regular migratory routes, but are referred to instead as nomads.  Unlike many birds, which have breeding grounds where they can be found in summer and non-breeding grounds where they can be found in winter, nomadic species move across the landscape to follow food resources wherever they happen to be.  This means that where groups of birds are to be found at any given time of year can be very unpredictable.  They seem to congregate where there are large concentrations of food, although how they find their food is a mystery.  For the Evening Grosbeak, these food resources are usually large insect outbreaks or areas where the coniferous trees have big crop of cones.  Other foods that Evening Grosbeaks seem to like are the Safflower and Black Oil Sunflower seeds they find at bird feeders.  One interesting dietary foible is that they seem to have a strong affinity for salt.  They have commonly been reported coming down to drink from mineral springs, and also have been shown to prefer soils that have had salt added over soils that have had nothing added.

Geographically, the Evening Grosbeak has been expanding its range into the eastern United States in the past hundred years or so.  The first recorded sighting of an Evening Grosbeak in New England came in the 1890s, and the first breeding record was in 1940.  One thought as to why this eastward has been taking place is the extinction of the Carolina Parakeet.  When the Carolina Parakeet, North America’s only native parrot, was alive their diet consisted predominantly of large seeds.  When they were driven to extinction, this food resource was left open, and the Evening Grosbeak had the equipment to break into such seeds as Bald Cypress cones which other birds were too small to tackle.

The number of subspecies of Evening Grosbeak has been a developing story since the late 1800s and has had its’ fair share of confusion.  In 1874 a natural historian, Ridgeway, found that birds in Mexico looked different from the birds he was used to seeing in the eastern United States. The yellow eye-stripe of the male Mexican birds was longer and wider than eastern birds and the bills were longer, wider, and less curved.  This led him to separate birds in the western half of the continent from the birds in the eastern half of the continent thereby creating two subspecies.  In 1917, Joseph Grinnell at the Museum of Vertebrate Zoology at the University of California, Berkeley, took a closer look.  He noticed that the birds that Ridgeway had found were representative of the birds in Mexico, but that they were subtly different from birds found in other parts of the western US.  Grinnell agreed that the eastern birds represented one subspecies, but he separated the birds in the western US into four subspecies based on differences in plumage color and brightness, and slight differences in bill shape and size.  The resulting five subspecies were the accepted taxonomy until 1957 when the American Ornithologists Union decided that the slight differences in bill shape and size that Grinnell had described were not enough to warrant subspecies status for some of these populations.  Instead, they settled on three subspecies.  The eastern birds represented one subspecies, as everyone agreed, the birds from Mexico represented a second, and birds from the rest of the western United States represented a third.  Since 1957, these subspecies have been the three to have accepted taxonomic status.

Regardless of how many subspecies exist, some people have taken notice of trends that stretch across the whole species.  One disturbing trend was found by scientists at the Cornell Lab of Ornithology who examined Christmas bird count and breeding bird survey data and found that numbers of Evening Grosbeaks have been declining across the country. Over the past two decades, Evening Grosbeaks have been seen at fewer and fewer sites.  Additionally, the sites that still have their Evening Grosbeaks have been observing smaller and smaller flocks.  Since these birds are so unpredictable in their movements, and they frequently live in the back country where Christmas bird counts are rare, it is possible that the birds are simply going to places where they are not being seen.  However, since the Cornell scientists only found declines all across the country, and found no population increases even at small local locations, the continent wide population decline seems like a real possibility.

In terms of vocalizations, Evening Grosbeaks present other interesting traits.  Evening Grosbeaks have a number of vocalizations.  One kind of vocalization is the flight call.  This is a short, single-note call that seems to function in flock movement coordination.  This call has been observed to vary from population to population in different parts of the country, and the different variations seem to be quite distinct.  Each variation was called a Type and given a different number.  So, now different birds have been identified as producing Type 1 flight calls or Type 2 flight calls all the way up to Type 5.  No bird has ever been found to make more than one Type of flight call, but birds that produce different flight call types do sometimes occur in the same place at the same time.  Interestingly, when the distributions of these different flight call Types are mapped across the continent, they match where Joseph Grinnell mapped out his five subspecies!

So what is going on here?  Can birds use flight calls to identify other individuals such as their mate?  Do they prefer to associate with other birds that make the same type of flight call?   Do the different flight call types play a role in choosing a mate?  Do birds that make different flight call types prefer different sized seeds?  Are the birds that make different flight call types genetically different as well?  How are the differences in flight call types able to persist when these birds move around and overlap with each other?  These, and other questions, are what I hope to find out.  So do you have Evening Grosbeaks, the ABA Bird of the Year, coming to your feeders?  Let me know, and I will report back on what I find!

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