Feeds:
Posts
Comments

Posts Tagged ‘Songbirds’

A sad landmark has been reached.

A fellow species has fallen.

Let us each take a quiet moment to consider what we have lost.

Pyrocephalus dubius 2

A male San Cristobal Flycatcher

The landmark that has been reached is the first extinction of an endemic Galapagos bird species. For a long time, many species of animals found on the Galapagos Islands, and no where else on earth, have been declining. Biologists have warned for years that if dramatic steps are not taken, many of these species will go extinct and the ecosystems of the Galapagos Islands will be impoverished forever. Exactly this has now happened. The San Cristobal Flychatcher (Pyrocephalus dubius) is the first species to fall. Found only on a couple of the Galapagos Islands, this stunning flycatcher used to be thought of as a subspecies of the more widely distributed Vermillion Flycatcher (Pyrocephalus rubinus). Recent studies, however, have shown that it and the Galapagos Flycatcher (Pyrocephalus nanus), also a former subspecies of the Vermillion, both warranted elevation to full species status. And now, surveys of the islands have found that there are no San Cristobal Flycatchers to be seen.

Pyrocephalus dubius 1

A female San Cristobal Flycatcher

The reason for this tragic loss is not completely known, but it is likely due in part to invasive Brown and Black Rats and in part to the parasitic fly Philornis downsi. The rats have been transported to the islands unintentionally by humans. They climb up trees and eat the eggs out of the nests of many songbird species. The flies were another accidental introduction to the islands by humans when their eggs were brought to the islands on imported fruit. The fly larva infect nestling songbirds feeding on blood and tissue. Infestations frequently become severe enough to kill the nestlings.

How many more species will go extinct before sufficient actions are taken? How many more species can go extinct before the ecosystems of these fragile islands collapse into a ghost of their former selves?

I leave that to your consideration.

Read Full Post »

My recent trip to Ireland brought me a bunch of lifers, 34 in total! To the non-birders reading this, a ‘lifer’ is the first time you see a particular species, thereby allowing that species to be added to your life list. Getting so many was pretty darn terrific, and it made me realize that there are many lifers still to be had in the US. Now, I am not supper obsessed with adding to my life list. Some people are all about getting the next species added to their list, and then it is off the next one and the next one after that. This style of birding has never really appealed to me. I really enjoy spending time with a bird and getting to know it in more detail than is possible from only a first impression. But, that having been said, seeing something new is pretty exciting. So, when I read on a local bird list that several Grasshopper Sparrows (Ammodramus savannarum) had been sighted not far from my house, I decided to go and have a look. Grasshopper Sparrows are a bit of a nemesis bird for me. They are not particularly rare in central California where they breed in small numbers out in grassy and weedy agricultural fields. But, while I have spent lots of time in such habitats, I have never seen or heard one. So, with some detailed location notes in hand, I drove into the agricultural land south of Davis, CA one Tuesday morning to see what I could see. Once I reached a particular stack of hay bales, I parked the car and got out to walk along the county road I had driven down.

That morning was a really pretty one in the lands south of Davis. There was an almost complete cloud cover except to the west where the trailing edge of a weather system was leaving the sky open and clear. A moderate breeze was blowing, as it almost always does out in the wide open fields and pastures. The birding was pretty nice as well. As I walked down the road, I passed a partially mowed hay field on one side and the field on the other was flooded with just a few inches of water. The combination of grassland and water made for a nice diversity of birds, even though I was only there for half an hour.

As soon as I stepped from my car, I heard the hoarse call of a Ring-necked Pheasant. Western Meadowlarks were singing all around. A flock of some 90 Red-winged Blackbirds were foraging in the grasses above the water line in the flooded field. In the areas of slightly deeper water were a pair of Great Egrets and one female Mallard. I was pleasantly surprised to see 4 Wilson’s Phalaropes swimming in tight circles in one corner of the flooded area. Overhead, small groups of Long-billed Curlew, impressively big for members of the sandpiper family, were flying from west to east going to find breakfast. And, as I stood and listened to the wind, I heard the double tick and high trill of a Grasshopper Sparrow! I heard one on each side of the road, and then another one farther down on one side. As I searched the grasses for the bird, I saw one take off and land on a barbed wire fence and sing, right in front of me! It was quickly joined by another Grasshopper Sparrow and then yet another! The second and third birds were young ones coming to beg food from the first adult bird. And there was still a bird singing somewhere on the opposite side of the road for a total of at least four Grasshopper Sparrows! The three stayed in front of me for a while, moving from fence to ground to grassy tuft before moving farther into the field and disappearing in the grasses. I was not able to stay much longer, but as I walked back to my car, I could still hear the occasional double tick and trill song drifting to me across the breeze.

Getting to see these birds was a real treat for me, and I am definitely going to make a point of seeing some of the other North American species that I have never, quite crossed paths with. I think Sage Sparrow, another nemesis bird, will be one I will work on this summer.

Read Full Post »

I was out along the shores of Bucks Lake near Quincy, CA, last week, in the hope of getting some more of my field work done. Unfortunately, I did not think to check the weather report before I left. It has been so dry this summer that it did not even cross my mind that it might rain! Well, this was the day that rain it did. A lot! It started as I was driving up into the mountains, and did not stop all morning! When I got to Bucks Lake I parked near Haskins Creek and sat in my car for a while. I soon decided, however, that if I was going to up there, I might as well get out and do some birding. Maybe I would find some Evening Grosbeaks and see what they were up to in the rain.

Well, I did not find any Evening Grosbeaks, but I did get a good bit of birding in. I spent most of my time watching a big flock of White-crowned Sparrows, Golden-crowned Sparrows and Dark-eyed Juncos. Watching the birds forage in the rain was pretty cool. The lighter showers were not enough to bother most of the birds most of the time, and so they stayed along the roadside. It was only when a heavier downpour began that the birds would retreat into the cover of some dense willow thickets and wait until the rain lightened up again. I was struck, as I often am, by how dramatic an event migration is. Just last week, I was up in the mountains and saw my very first White-crowned, and Golden-crowned, Sparrows of the fall. Now, here is a flock of about 60 White-crowns and 20 Golden-crowns! Just like that, this synchronized wave of millions of birds has descended upon California!

As I continued to watch this flock, I started to pick out the odd birds that were mixed in. There was one Song Sparrow. A few Yellow-rumped Warblers flew in and out. Of these, two were of the Myrtle subspecies, which is generally the more eastern subspecies, so they were cool to find. I continued to watch through my binoculars, but suddenly the birds that I could see scattered. I took my binoculars down and saw that the whole flock was racing for cover! I looked up and found out the reason for the sudden panic. An adult Red-shouldered Hawk was flying right up the middle of the meadow and directly over the foraging passerines. The hawk did not actually make any directed move towards the small birds, but instead flew off into the trees. A little later, an adult Bald Eagle also flew, rather dramatically through the rain and mists, over the flock. This bird did not cause any reaction from the sparrows at all, and neither did a Common Raven a few minutes after the eagle. The sparrows can apparently tell the difference between various predators, and know which they should worry about. I thought this demonstrated some pretty fine ID skills on the part of the sparrows!

In spite of being cold and wet and not finding any Evening Grosbeaks and not getting any field work done, I really enjoyed that morning in the storm. It made me realize how much I have missed being out in the rain!

Here is my full species list:

Bald Eagle (1)

Red-shouldered Hawk (1)

Northern Flicker (2)

Steller’s Jay (11)

Common Raven (1)

Mountain Chickadee (3)

Red-breasted Nuthatch (3)

Golden-crowned Kinglet (5)

American Robin (8)

Yellow-rumped Warbler (3 Audubon’s, 2 Myrtle)

Song Sparrow (1)

White-crowned Sparrow (60)

Golden-crowned Sparrow (20)

Dark-eyed Junco (20)

Brewer’s Blackbird (1)

 

Read Full Post »

On the morning of the 19th, I was out birding in the early morning along the Clarksberg Branchline Trail in West Sacramento. I was poking around the section of trail just north of Lake Washington Blvd. from about 6:20am to 7:30am. It was one of those morning where I decided to not worry about covering a lot of ground. Instead, I wanted to take my time, relax, and covered the ground thoroughly really investigating each bird I heard or saw and taking my time to enjoy it. I was rewarded by some lovely views and fun finds. My species list is at the end.

Right as I started my walk, I saw a long, slim animal run out from the edge of the blackberry tangle along the trail ahead of me. It stopped out in the open for a short moment and then continued on towards the large pond just east of the trail. To my surprise, I realized that it was a Mink! I have seen River Otters at this location before, but never a Mink. What was it doing here? As I scanned the pond, there were no birds swimming in the water except three domestic ducks that were probably dumped here to become feral. As I stood by the water’s edge, I head several birds in one of the willows that grow right on the bank. I walked that way, and found a Marsh Wren singing in the cattails and my first White-crowned Sparrow of the fall for West Sacramento! It was a really good looking  adult bird that was sitting in, and calling from, that willow. Soon the Central Valley will be covered in millions of White-crowned Sparrows back from their breeding grounds in Canada and Alaska to spend a comparatively warm winter in lovely California.

As the sun rose, beautifully tinged blood red by the smoke from the King Fire that is burning just east of Sacramento, I stumbled my way into a mixed insectivore flock. At this time of year, with migrants and vagrants wandering all over the country, mixed insectivore flocks are always worth spending some time with. Often, many birds will come together to forage, and this can attract individuals of species that you might not get to see otherwise. In this case, the bulk of the birds were Bushtits, maybe 25 of them, which were streaming from oak tree to oak tree giving their high pitched contact calls as they told each other where they were. As I watched these tinny birds, I started to notice the other species in the flock. A Western Scrub-Jay, a coupe of Northern Mockingbirds, and a lovely pair of Black-throated Gray Warblers which came low in some small trees and afforded me some great looks! The day ended with a total of 5 of these warblers which is a lot compared to what I am used to seeing in winter, which is just one or two.

After I left the mixed flock, I walked out into an open field that had been mowed and tilled. As I walked along the line of tree that marks the edge of this field I was treated to a fast triple-raptor encounter. First, a Swainson’s Hawk took off from one of the tree tops and doove down into the field. It pulled up before landing, apparently the prey animal it had seen got under cover in time to avoid becoming breakfast for the hawk, and returned to its perch. right after that a Red-tailed Hawk came barreling of the line of trees and cruised over the field and away. As I was watching the Red-tail, a Red-shouldered Hawk started calling behind me. It was circling at about tree top level and proclaiming dominion over this patch of ground. The Red-shouldered Hawk is a resident bird that I see almost every time I bird this area. The Swainson’s Hawk breeds nearby somewhere, but then leaves, with the rest of it’s species members, to head south in winter which is something that will be happening soon. The Red-tail could go either way in that it could be a resident or a migrant just here for the summer. How these different hawks interact and adjust to one another is a question that has long interested me. Take the Red-shoulder, for instance. It has a territory that it defends year-round. Suddenly, in mid-March this Swainson’s Hawk shows up trying to find a place to settle and nest. How does the Red-shoulder respond? Does it simply move out of the larger hawks way? Do the birds compete and adjust their territory boundaries to one another? Do these birds eat different enough foods that they don’t really care about each other? And then, how does the Red-tailed Hawk fit into all this? How resident birds adjust to the comings and goings of migrants is not something that has gotten a lot of attention and I think could make for a really cool research project.

Looking at the open field with the naked eye, I did not see anything out there, but just on a whim I decided to give it a scan with my binoculars. As I looked slowly across the field I saw no less than 15 Killdeer scattered about foraging. So much an empty field! It reminded me that a lot can be hiding and go unnoticed when only a cursory inspection is done.

This was a really nice morning birding. I saw some beautiful birds that got me thinking about interesting ideas and taught me a thing or two all at the same time.

Double-crested Cormorant (1)

Turkey Vulture (1)

Canada Goose (12)

Red-shouldered Hawk (1)

Red-tailed Hawk (1)

Swainson’s Hawk (1)

Killdeer (15)

Western Gull (3)

Rock Pigeon (70)

Mourning Dove (20)

Anna’s Hummingbird (3)

Belted Kingfisher (1)

Nuttall’s Woodpecker (4)

Black Phoebe (3)

Western Scrub-Jay (11)

American Crow (12)

Oak Titmouse (4)

Bushtit (25)

Bewick’s Wren (3)

Marsh Wren (1)

Blue-gray Gnatcatcher (1)

American Robin (5)

Northern Mockingbird (2)

European Starling (30)

Cedar Waxwing (8)

Orange-crowned Warbler (5)

Black-throated Gray Warbler (5)

Spotted Towhee (2)

California Towhee (1)

White-crowned Sparrow (1)

Red-winged Blackbird (30)

Mink (1)

Read Full Post »

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!

Read Full Post »

I just read an article, and then the paper it was based on, about songbird migration. It was published by a group from the Cornell Lab of Ornithology (including one person I used to work for). They used eBird records to examine where and when songbirds migrate and how these migratory movements correlate with weather patterns. What they found was that songbirds use different migratory routes in spring vs. fall,  moving in a roughly clockwise pattern. This makes the routes match wind patterns such that the birds take advantage of the strongest tailwinds in spring as they head north to their breeding grounds and face the weakest headwinds in fall as they move south to their non-breeding grounds.

I really like this study for several reasons. One is that much of our understanding of migratory movements in birds is based on waterfowl banding results. This is because there is a huge waterfowl data set due to hunters who report the bands on birds they shoot. This results in something like a 10% recovery rate for banded waterfowl (in comparison, songbirds banding has something like a 1%, or less, recovery rate for bands). However, any information that is gained by studying waterfowl movements may or may not be applicable to other birds. For example, most waterfowl are fairly strictly limited in the type of habitat they can use. Other birds are much more general, so the patterns may well be different. As our abilities to track bird movement have increased, our understanding of migration has also increased, and (as in so much of life) the picture is more complicated the more we learn. So this new analysis broadens our understanding of what migrating birds do. Waterfowl generally use one of four fairly narrow migratory corridors, called flyways, as they move north and south each year (the four flyways are the Pacific, Central, Mississippi, and Eastern). Songbirds, it turns out, use much wider swaths of the landscape which can be roughly divided into three flyways (Western, Central, and Eastern), and the areas used within each swath are different in spring (more to the west) than in fall (more to the east).

Another reason that I like this study so much is that is relies on citizen scientist. The records that the authors used were from eBird, which is an online database run by Cornell that anyone can add to. It is a way for birders to post their sightings and then see how those sightings fit into the larger picture of what birds are doing across the state, country, continent, or even hemisphere. By tapping into this vast knowledge base, the authors were able to examine where birds were being seen and when at a broader geographic scale, finer resolution, and including more species then ever would have been possible if the authors had tried to collect the data themselves. So, this study stands as yet another example of how important individual birders are to bird research and conservation. It is also another reminder of how much value there is in birders and ornithologists talking to each other!

So, a great study with interesting results and creatively using a citizen science data set. What could be better?

Read Full Post »

My mom recently asked me about the migratory habits of the Western Meadowlark (Sturnella neglecta).  I gave her what I knew off the top of my head, but realized that I did not know all that much detail on the subject, and so I went reading.  What surprised me most in what I found was just how little there was to find.  For being such a common species, there is a great deal that has not been recorded about their migratory biology.  For example, even the sizes of the flocks that Western Meadowlarks migrate in are not well documented.  This is a common situation for short and medium distance migrants, as much more focus has been on the study of long distance migrants.

Here is some of what is known.  After the breeding season, small loose flocks start to assemble.  This is usually in September and October depending on location.  These flocks can overwinter if conditions are mild, or they may migrate together if conditions are harsh.  In the northern and central portions of their range, Western Meadowlarks are diurnal migrants, and they can travel as far south as central Mexico.  While this can include individuals moving a distance of up to 1000 km (as indicated by a small number of band recoveries), most Western Meadowlarks seem to follow a pattern where the whole population moves a bit south as a loose unit, so the northern most breeding population will remain the northern most non-breeding population.  Birds that breed at higher elevations tend to be altitudinal migrants moving downslope during winter.  During migration and the non-breeding season, they generally seek out suitable habitat in sheltered valleys during periods of harsh weather.  Western Meadowlarks are actually non-migratory in much of the southern portions of their geographic range, a belt that stretches from Kansas to California.  Even less in known about the spring migration of this species, but migrants generally return to breeding grounds in March and April.

So, keep your eyes out for Western Meadowlark flocks.  You never know what you may learn!

Read Full Post »

Older Posts »