Thursday, January 17, 2013

Eagle Update

The past couple weeks have seen few changes in the places our GPS tagged eagles have been traveling. The females are still seemingly content to stay on the Chilkat, while the males are still southward in and around Prince Rupert.

The adult female, 3E, and the immature female, 4P, are both right around the area we initially caught them:

3E



4P


The mature male, 3C, is still moving around a bit, bouncing eastward, then westward again, then a bit to the southeast, though he is still near Prince Rupert. You can see pretty clearly on this image how he has been following waterways closely as he travels.

3C



The immature male, 2Z, has now been in Prince Rupert for more than a month. This may be where he stays until spring. It seems 2Z is spending time feeding at a landfill near the city. Since he is a younger bird, he may not be able to compete with other eagles for better food sources (e.g. fish), or perhaps his hunting skills aren't quite up to scratch. Whatever the reason, doesn't appear to be following the salmon, but rather, the dump truck.

2Z


In the upper right hand corner of the photo above, you can see a little portion of 3C's track, where the two birds were near one another for a short time.

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Monday, December 17, 2012

Trivia Question of the Week

This week's trivia question is appropriately related to eagle migration: How far do bald eagles migrate?

Hint #1: It's not nearly as far as an arctic tern

Hint #2: We've determined these distances through the use of leg bands and telemetry.

Read more »

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Thursday, December 13, 2012

Eagle Update!

Although 4N's tag is out of commission, we still have four birds to follow! We're always excited to see where these eagles are moving, and we hope you are, too.

First up, the females! Both females, 3E, the adult, and 4P, the immature eagle, have been sticking around the Chilkat Valley.

3E has made a couple trips to the ridgeline south of the Chilkat, but is otherwise hanging out around the area between 19- and 21-mile on the Haines Highway-- pretty much the only region of the Chilkat River that is unfrozen this time of year:


Read more »

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Monday, December 10, 2012

4N

Rigby and I are back in Santa Cruz, adjusting to things we haven't seen in a while-- stoplights, traffic, and sunshine, just to name a few. We've finally managed to get internet up and running in our new place, so it's back to blogging!

Today's entry focuses on one of the more frustrating aspects of working with wild animals: data loss. So far, we've been getting pretty reliable information from the GPS tags on our eagles, but the data are not without problems. Since the tags are solar powered, they need to have reliable sunshine to keep the battery charged and the device functioning. In southeast Alaska, where snow is a daily occurrence and daylight hours are rapidly diminishing, it's tough for the tags to get the juice they need. This is complicated by the fact that the Chilkat River is surrounded on both sides by relatively steep mountain ranges. Even when the sun does come out, much of the river is still in shadow.

Read more »

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Wednesday, November 28, 2012

Trivia Question of the Week, and what's up next

This week's trivia question is paired with statistics for this season's fieldwork. What is the animal we saw most frequently on our trail cameras this summer?

Hint #1: This contest was pretty close, with a couple hundred pictures or so separating the first and second most frequently sighted animals.

Hint #2: In broad terms, the second most frequently sighted type of animal actually beats out the first, but in terms of species, there is one clear winner.

Hint #3: Their name starts with "B"

Hint #4: They're furry

Hint #5: If you anger them, they'll eat your face off. :)

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If you guessed Brown Bear, you're correct! You've obviously been following along with us this season. Or you know that bears will eat your face off. Either way, congratulations!

"Bears" as a broad category, was actually beat out by "birds"-- we saw more birds overall on our trail cameras than bears. Whereas the "bird" category is composed of eagles, raven, magpies, crows, mergansers, blue-winged teals, varied thrushes, and others, however, the "bears" category is all brown bears. We didn't see a single black bear on our trail cameras this season.

For our trail camera work this summer and fall, we captured:
  • 24,767 photographs, total
  • 6,605 images of bears
  • 7,841 photos of birds
  • 71 photos of canids (wolves, coyotes, and domestic dogs)
  • 332 mustelid photos (mink and marten)
  • 59 photos of rodents (mice and red squirrels)
  • 94 photos of humans (not including ourselves)
  • 0 photos of lynx, wolverine, black bear, or lagamorphs (hares or rabbits), although these species all live in the area

Now that I'm headed back to Santa Cruz and our field season is over for the year, you may be wondering what's in store for the blog. Will I keep updating? What can you expect to see?

Well, by my calculations I've shared around 60 of our trail camera photos here on the blog. That means there are an additional 24,707 photos I could post! :)  I'll continue to post trail camera photos from time to time, in addition to videos I'm currently working on putting together that detail sequences of trail camera photographs, like bears or eagles feeding on the salmon carcasses.

And don't forget about our eagles! We'll continue to follow the movements of the five eagles we tagged with GPS/satellite transmitters, and we'll post these locations for you as we go along.

There are several other stories from the field that I haven't yet had time to put together into blog entries that I'm hoping to work in within the next couple of months. We're also working on putting together a fully-fledged website for Ecology Alaska. So among trail camera photos, eagle movement data, stories from our fieldwork in Haines, and perhaps a few entries detailing the life of a wildlife biologist outside of the field season, there should be plenty going on here on the blog. I imagine that the rate of posting will decrease come the beginning of the year, but I will attempt to continue posting at least one entry and one trivia question each week.

Stay tuned, and as always, feel free to let us know what you think, by leaving us a message in the comments or sending us an email at ecologyalaska [at] gmail (dot) com.

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Saturday, November 24, 2012

Where are they now? (cont.)

The male eagles we tagged, 3C and 2Z, have been busy! Unlike the females, the males have been traveling around a bit more. We suspect this is because males, who are significantly smaller than the females, aren't able to compete as well for food.

3C, the adult male, is still in the Chilkat Valley, although he's been wandering away from the river itself:

Read more »

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Thursday, November 22, 2012

Where are they now?

The great thing about attaching satellite transmitters to our eagles is that the information is fed to us on a regular basis. If the eagles leave the area, we won't have to worry about tracking them by foot or in a plane-- the satellites will download the GPS locations of the birds and we can access the information online. Our transmitters collect a GPS location every hour during daylight, and we receive a list of the locations every two to four days. This means that we're already seeing where our eagles are moving!

Read more »

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Monday, November 19, 2012

Trivia Question of the Week

Last week, when we posted about the capture and processing of bald eagles, we mentioned that, up until five years of age, eagle molting patterns can be used to determine how old a bird is. Past five years of age, when eagles reach adulthood and take on the characteristic appearance of their species, with a white head and tail, it's impossible to tell how old they are. So, how long do bald eagles live?

Hint #1: The fact that eagles don't mature until five years of age suggests that they're fairly long-lived-- animals that live shorter lives mature earlier.

Read more »

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Wednesday, November 14, 2012

Meet the eagles!

Get ready to meet our eagles! We captured five eagles on the Chilkat River this year, and we'll be tracking their movements from now until the transmitters fail (or fall off, or the eagle... dare I say it?... dies)(Which is not going to happen. I hope.). If all goes as planned, we'll see the daily movement patterns of these eagles for at least the next three years! We can't wait to see where they spend their time during different parts of the year.

We captured our first eagle late morning on Saturday, November 3rd, using the ballistic net. A sick juvenile eagle couldn't resist the free food in front of our net launcher, and began to feed. An adult eagle came and roused the juvenile off the bait, and fed in its place. The result? We netted our first bird, a healthy, hefty adult female!

4N, just after being freed from the net

Read more »

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Monday, November 12, 2012

To Catch a Predator (Part 2)

Our snares are set, our net is at the ready, and we've been standing around in the snow since dawn, waiting for the eagles to come in. We keep a close eye on our snares and bait with binoculars and spotting scopes.


Each time an eagle nears a perch we've erected, or flies over the bait in front of our net launcher, we hold our breaths. Typically, the eagle moves on, or perches nearby. We sigh, and wait for the next close encounter.

Then, unexpectedly, an eagle flies down and lands next to the chum carcass set out in front of our ballistic net. It looks around, cautiously, before beginning to feed. We wait until the eagle has its head down, focused on tearing a nice, juicy bit of chum off the carcass, and then-- "Fire!" We trigger the ballistic net remotely, and the .22 gauge blanks power three padded projectiles, launching the net from its housing out and over the bird.

"We got it!"

Everything is a rush. We sprint from the roadside, where we've been watching, down the river embankment to our freshly-netted eagle. We must move quickly, to ensure that the eagle doesn't escape from the net, or get too tangled. Immediately, we secure the talons of the eagle in our hands, and place a hood over its eyes. Eagles receive most of their sensory information visually, so when they can see what we're doing, they get stressed. With the hood on, however, they immediately calm down, and are relatively docile in the hand. Unlike many mammals, birds do not need to be anesthetized during handling. The hood keeps the eagles calm enough.

We then begin the process of extracting the eagle from the net. Here, Steve Lewis and Dr. Scott Ford work the netting off the eagle's wings.

Steve and Scott work the netting off the eagle
Read more »

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Saturday, November 10, 2012

To Catch a Predator (Part 1)

We just finished six intense days of eagle captures! In the coming week, we'll be posting several entries and many photos of our adventures, so check back often. Aided greatly by raptor biologist Steve Lewis of the US Fish and Wildlife Service and Dr. Scott Ford, an avian veterinarian, our efforts netted five total eagles, so we were able to deploy all of our satellite tags!

Eagles surveying the Chilkat River

As the weather turns chillier and the rivers begin to freeze, more and more eagles are congregating along a small stretch of the Chilkat River that hosts open, flowing water. This two- to three-mile stretch of river stays unfrozen year-round as a result of unique geology-- groundwater percolating upward from natural springs near the confluence of the Tsirku, Klehini, and Chilkat Rivers maintains water temperatures just above freezing. Eagles come to this area to access chum and coho salmon. When rivers freeze elsewhere, this spot is one of the only places eagles can find a meal!

Read more »

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Wednesday, October 24, 2012

More Trail Camera Photos!

This latest series of trail camera photos comes to you courtesy of the Herman Creek Chum salmon run. Coho and Chum are pretty much the only salmon running this time of year. Coho are a little harder to come by, so anything that's eating salmon is probably going to be eating Chum.

Like these bears:


Or these. How many bears do you see in this photo?


Did you count four? There are the two obvious ones, then part of a third on the right edge of the frame, and part of a sneaky fourth behind the branches along the left edge of the frame.

Here is a less sneaky adult eagle:


and some mergansers and a raven at that same site:


We had a couple coyotes in this set. Here's one of them:


Eagle party! More eagles have been arriving every day. There is a citizen science group in Haines that does weekly eagle counts. Last weekend the tally was 775. It won't be too much longer before there are thousands.


Take a look at this handsome youngster:


We also have some ravens fighting over scraps.


Another photo of a wolf!


And our first moose photo! Well, sort of, anyway.


This last one is tricky. Along the bottom part of the frame in the middle, there is another "first" camera sighting. A rodent! It's impossible to identify the species, or get much beyond "rodent-like small animal." But there it is! Maybe not quite as grand as the brown bears, wolves, and eagles, but I think it's fun to see them just the same.



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Sunday, October 21, 2012

Trivia Question of the Week

With plenty of eagles here already and more on the way, this week's question is appropriately eagle-themed.

What is the grip strength of an adult bald eagle?

Hint #1: The tendons in bird's legs have tiny ridges on them that interlock with the tendon sheaths when flexed, holding the talons closed without any additional effort on the part of the bird. Ever wonder why birds don't fall off branches while they're sleeping? It's because the tendons in their feet are locked in place.

Hint #2: The largest species of eagle in the world, the Harpy Eagle, has enough grip strength to crush the bones of large mammals.

Hint #3: Bald eagles may not be able to crush large mammal bones, but they can definitely do some damage to a human wrist.

Hint #4: Their grip strength allows them to pull salmon equal to their own weight from the water.

Hint #5: An eagle's grip strength is more than 10 times that of a human hand.

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If you guessed 400 pounds per square inch (psi), then you are a true ornithology nerd champion and know far more about bald eagles than is healthy anyone else. The grip strength of the average adult human, by comparison, is only about 20 psi.


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Monday, September 24, 2012

Autumn

This past Saturday, the 22nd, was the official first day of autumn. Having grown up in Colorado, autumn has long been my favorite season. Autumn days in the Rockies are mild, sunny, and warm, a wonderful relief from the blisteringly hot days of summer. Nights are crisp and cool. And the colors! Aspen, cottonwood, willow, and maple turning stunning shades of yellow. I missed autumn a lot when I moved to California.

Fall weather in northern California is nice, too. Sunny, not as much fog in the mornings, and warm. But most deciduous trees there keep their leaves year-round, the evenings aren't cool, and there is no nip in the air that suggests impending snow. It's just doesn't feel right. :\

Luckily for me, Alaskan autumns are a lot like Colorado (except with more clouds, humidity, and rain). Gorgeous colors, blankets of yellow, orange, and the occasional red, have spread across the landscape these past few weeks. Temperatures have dropped. Some afternoons, when the breeze is right, you can stand in a shower of gold as leaves falling from trees catch the pale sunlight.

I love autumn.

The eagles are arriving! Each day more and more eagles appear along the Chilkat, staked out on the river flats to feed on the first of the Chum. What makes for a better photograph than golden cottonwood leaves, blue mountains, and an eagle?


For a couple weeks, the weather here was overcast and rainy almost every day. We literally did not see the sun shine for ten days or more. A bit depressing, and a sure sign of the winter to come. Luckily, late September has been kind to us, and we've hit a string of wonderfully sunny days. It's nice to see some blue sky again!


Before the snow travels low enough in altitude to make mountain travel tricky, we decided to make one last trip up to the alpine tundra. Here is a view of the Klehini River from Flower Mountain. Autumn colors make their way into the highest reaches here-- just look at those deep reds of the low-growing plants. Tundra soils are thin (four inches or less in some places), but vegetation still manages to take hold. Alpine berries, willow, lichens, and scraggly, stunted spruce make their homes here, providing food for mountain goats, moose, songbirds, and alpine ground squirrels.

Quite a view, eh?


With a string of sunny days, we've also been making good use of the raft. Rafting down the Klehini affords us opportunities to set trail cameras south and west of the Chilkat, where we see evidence in tracks of moose, wolves, and the ever-present bear. There are plenty of eagles on the Klehini as well!


Mountains, river, blue sky, and birch, cottonwood, alder, and willow changing colors? Alaska, you are wonderful.


And eagles! More and more eagles! The yellow background of these cottonwood leaves may be a bit distracting in this photo, but the colors sure do make it stand out.


Alaska isn't the only pretty place this time of year. Canada has its fair share of gorgeous locales, too. How about this view of Dezadeash Lake, in the Yukon Territory?


Or this lovely little trail, on the route back from St. Elias Lake in Kluane National Park?


Not enough autumn for you? Oh, all right. Here's one last picture: The Tatshenshini Valley.


Be honest now-- who's in the mood for pumpkins, cider, sweaters, or a bit of Halloween fun? Butternut squash ravioli? Homemade applesauce? Pumpkin-spice latte?

Or how about, for those of you lucky enough to live in places where there's an actual autumn, a bit of time spent outdoors enjoying the leaves.

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Thursday, September 13, 2012

The Chum are Coming!

Over the past couple weeks, the Sockeye runs have been slowing down. Most of the Sockeye in the spawning areas have now died, and few new Sockeye appear each day. Carcasses litter the streams, ponds, and banks. We've gradually seen less activity on our trail cameras-- fewer bears are visiting key feeding areas, and we come across fewer partially consumed carcasses along bear trails. But the bears have no need to be concerned. There are plenty of other fish in the stream!

Pink salmon are still running, although their numbers have decreased, too. Coho salmon also continue to spawn, but spawn in much lower densities and across larger areas than Sockeye, so it's more difficult to locate their spawning grounds. The bears' next big target, though (and ours, too, for our trail cameras) are the Chum. Just last week, there were only a few fish in this spawning channel off of Herman Creek. Already, the densities are quickly increasing:


Chum salmon are also called Dog and Keta. Keta is the name typically used by canning companies (after all, who wants to eat "chum" anyway?). Chum and Pink salmon are the least commercially valuable fish. Most commercial fishing and canning operations prefer King and Sockeye, but many subsistence fishers in this region like Chum just fine-- especially when smoked, fresh-caught Chum has good flavor.

Chum salmon spawn in autumn, from roughly the end of August through the winter, or at least until the rivers freeze enough to prevent their travel upstream. Chum spawn by the hundreds of thousands, and much like Sockeye they pack themselves into their spawning areas. Chum can pack themselves in even greater densities than the Sockeye. Sockeye are limited by available fry rearing habitat-- once their eggs hatch the young salmon fry need suitable places to grow for a year or two before migrating to sea. Thus, Sockeye need good places to lay their eggs that are also in areas fit for little fish to grow.

Chum, however, are limited only by spawning habitat. Their fry migrate to sea more or less immediately after hatching. Chum salmon don't need to find suitable places for their fry to grow, only good spots for the eggs to hatch. As long as they can locate nice, rocky substrate with good water flow, they can spawn, so Chum find whatever spawning habitat is available, even if there are already hundreds of other fish around. This makes them easy for wildlife to access. Just walk up to the water and grab one!

With the weather quickly cooling and the Chum beginning to run, the eagles are beginning to congregate. We've started to see far more eagles around Haines recently. Gradually over the next month, the water level of the Chilkat River will drop, exposing the river flats and providing many shallow areas for wildlife to access fish. The Chum run will increase, until the braided areas of the Chilkat are packed with fish. And, as temperatures continue to decrease and freezing begins elsewhere along the coast and in the interior, more and more eagles will travel to Haines to feast on Chum through the beginning of winter.

We will continue to set our trail cameras out to capture wildlife feeding on salmon. At the end of this week, we will take down our last set of trail cameras from the Sockeye runs, and, starting next week, will set our cameras on Chum spawning areas and on higher elevation wildlife trails. Once the eagles begin arriving en mass, we will also start working on the second part of our research here-- looking into eagle migratory behavior!

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Friday, September 7, 2012

More Trail Camera Photos

We've had our trail cameras up for just two weeks, and we've already been getting some great photos. Check out some pictures from our most recent download!

As usual, there are A LOT of bears:


 Look at the size of that Sockeye!


Who's there!?


Someone needs to lay off the salmon....


It's not all bears, though! Look at this raven and great blue heron:


And my personal favorite picture of the week-- we had a couple of wolves stop by! Here's a shot of one of them:


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Monday, May 21, 2012

Why do eagles migrate thousands of miles to feed on salmon?


Check out the feeding frenzy when the chum salmon arrive in the fall. This is only one half day of footage from our motion detecting cameras! Eagles pull out the salmon and other birds can access whatever is left.


But why do eagles migrate by the thousands to the Chilkat River from distant locations?
Read more »

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