Trivia Question of the Week

We learned last week that Pacific salmon can grow to very large sizes when they spawn, but how do they know where to spawn?

If Pacific salmon spend most of their lives in the open ocean, how do they find their natal streams (the streams in which they were born) when they return to freshwater to spawn?

Hint #1: Planetarium studies have indicated that some species of bird rely on celestial navigation, orienting themselves based on the location of specific starts in the night sky. But since salmon can't see the stars, this isn't a tactic they can utilize.

Hint #2: Birds and salmon do have a navigation technique in common, though. It's the same way many animal species, from bats to sea turtles, find their way.

Hint #3: Scientists believe that salmon use not one, but two navigational aids to return from the ocean to their natal streams.

Hint #4: The technique for traversing ocean currents to find their way to freshwater is thought to be different from the method salmon rely on in the streams themselves.

Hint #5: You may think Fido is good at sniffing things out, but he can't compare to a Pacific salmon.

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Photo credit: Natalie Fobes

The two primary navigational aids salmon rely on are magnetism and scent. When salmon are in the open ocean, scientists believe they travel primarily by orienting themselves with the earth's magnetic field, much like many migrating species, like sea turtles, birds, and bats. Once they reach freshwater, however, scent plays the dominant role in guiding salmon travel. Young salmon migrating out to sea, known as smolts (pictured above), imprint different scents from their environment as they travel downstream. This allows them to create a memory bank of scents, which they later can use as a scent-map of sorts to guide their return to their birthplace as adults.

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.

Trivia Question of the Week

After a one-week hiatus for the holidays (Happy New Year's, everyone!) we're back. This week's trivia question: How many feathers does a bald eagle have?

Hint #1: The average person has about twice as many hairs on their head alone as an eagle has feathers on its entire body.

Hint #2: Just because it's called a "bald" eagle doesn't mean it's actually bald. Bald eagles have feathers on their heads, too.

Hint #3: Eagles have relatively few wing and tail feathers. The long feathers on the wings used for flight? Only 23 on each wing. The tail feathers? 12.

Hint #4: Most of the feathers on an eagle's body are contour feathers, small feathers that give eagles their shape, and down.

Hint #5: The colder the region, the more down feathers an eagle is likely to have. So an bald eagle in Florida probably has fewer total feathers than an Alaskan eagle.

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If you guessed that bald eagles have an average of 7,000 feathers, right on! This number varies seasonally, as well. During the molting season and in the height of summer, when the weather is warmer, eagles have fewer total feathers because of the loss of down.

Updates: Eagles, 4N, t-shirts

It's time for some updates! First off, a look at where our four GPS-tagged eagles have been hanging out.

Not much has changed in the past couple weeks. Both females, 3E and 4P, continue to spend their time along the Chilkat River. We're beginning to wonder if both of these birds might be residents. There is still plenty of time for them to leave the area and travel southward, but for now it seems as if they are both perfectly happy sticking near Klukwan.

3E:

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Trivia Question of the Week

It's time for the TQOTW!

How long do brown bears hibernate?

Hint #1: When brown bears hibernate, they're not really sleeping the entire time. They rouse themselves periodically to keep their temperatures elevated. This is particularly true with females, who give birth to and feed young while in the den.

Hint #2: Although we expect bears to hibernate throughout the winter, this isn't always true. Some bears will be active mid-winter, although most will avoid the cold temperatures and heavy snow by denning up and sleeping it out.

Hint #3: Brown bears will add six to eight inches of fat before hibernation, which acts to store energy and for insulation. That has to last them quite a long time...

Hint #4: Although bears may wake during hibernation, they usually do not feed at all during this time period. A special hormone in their blood stream, leptin, works to suppress the bear's appetite.

Hint #5: A good general rule of thumb is that bears will hibernate from mid- to late-autumn through spring.

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If you guessed November through April, you're right on! Female brown bears around Haines, monitored by the Alaska Department of Fish and Game with radio collars, have been observed hibernating, on average, between November 6th and April 29th of each year. Some bears will enter their dens later and/or emerge earlier, and hibernation times vary widely based on geographic region. Black bears usually hibernate October through March. In some temperate ecosystems that don't see much snow, some black bears won't hibernate at all.

Feast

I've been sifting through our trail camera photos, trying to pick out the best ones to share, as well as identify those that detail animal behavior. We captured a few interesting events-- bears rubbing on trees and chasing after fish in the stream, flocks of crows appearing and disappearing just as quickly-- but since we're right in the middle of the holiday season, it seemed fitting to talk about feasts! When salmon are plentiful, bears will high-grade salmon, eating only the energy rich, fatty parts of the fish: the skin, roe, and brains. When salmon decrease in numbers, however, a bear will make good work of a salmon carcass, eating everything it can.

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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.

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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:

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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.

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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.

Southward Bound

It's hard to believe, but it's been exactly four months since Rigby and I arrived in Haines on the ferry from Prince Rupert. From the Southeastern Alaska State Fair, to hiking Mt. Ripinsky and the trails in Chilkat State Park, to learning about spawning salmon, subsistence fishing and canning, to setting out trail cameras and finally, trapping and tagging bald eagles, the last four months have been filled with a host of new experiences and opportunities. And bears.

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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:

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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!

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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.

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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

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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

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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!

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Coming soon...!

Things have been quiet here on the blog lately, but don't worry. There's a reason. A very good reason, in fact.

We've been out. Working from dawn to dusk. Trapping bald eagles.

Yep.

More soon- with plenty of pictures!

Trail Camera Photos: Marten Edition

Sometimes it seems like all of the photos we capture are bears and birds. But we do get a handful of other animals, too. Like marten! These members of the weasel family are omnivorous, and consume both plants and animals. They prey on squirrels, rodents, and small birds, and are excellent climbers. They're also attracted to carrion, and have made several appearances on our trail cameras. What marten can resist a free dead salmon?

Marten are closely related (and strongly resemble) another routine visitor to our trail cameras, mink. Marten are a little smaller, have more triangular faces and pointed ears, and seem to have ridiculously long legs:

In a lot of our marten photographs, the animals are looking directly at the camera. They're pretty curious! A lot of our photos are blurry, too, because they dart around so quickly. But here are a couple other marten photos that came out nicely, even if they aren't in color:

Hooray for mustelids!

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.