February 25, 2006

Second Eaglet

chick compareCongrats to the parents once again! Our second eaglet took a little extra time coming into the world, but we're glad it finally got here.

Throughout the day on Friday, we saw a small hole in the second egg, but after many hours, the chick didn't seem to be making much progress. Finally late on Friday afternoon (around 5:30pm) the chick broke through the egg; this was a 36-day incubation and puts it about 2 1/2 days behind the oldest.

For those keeping score:

1st chick:
Egg laid - Jan. 17
Hatched - Feb. 22
36-day incubation

2nd chick:
Egg laid - Jan. 19
Hatched - Feb. 24
36-day incubation

Because bald eaglets are the fastest growing birds in North America, chicks that are only a few days apart can look very different. In fact not that long ago, ornithologists (or bird biologists) thought bald eaglets were hatching weeks apart because there was such a difference in their sizes. It turns out the chicks were only a couple days apart, but they were growing very rapidly.

In raptor families, the firstborn will always be the dominant chick -- it will get fed first and get fed the most. Even in a two-chick nest, you can see competition between the chicks, especially if the food supply is tight.

Last year we had three eaglets, with the third chick born five days after the first, and we honestly didn't know how the small third eaglet would fare in a nest with two bigger siblings, that together would demand most of the food. But the parents did a great job of making sure that each of the eaglets got fed, and we were pleasantly surprised to see all three chicks fledge successfully in the spring.

2006feed.jpgIn this year's Eagle Cam nest we've seen some great shots of the mother eagle feeding the young. In fact we've seen her working her way around to both sides of the nest or reaching over the head of one chick in order to give each eaglet some food. What's amazing is that although the mother is a powerful raptor -- bigger than even the male -- she has a very gentle touch when placing food into the eaglet's mouth. Here you can see two close-up shots from our 2005 cam showing how the mother hands off tiny bits of food. Some cam watchers have asked if eagles regurgitate the food, and the answer is no. The adults tear off the food and give it to the eaglets with their beaks.

The parents will continue feeding the chicks for a while because tearing meat from fish and ducks is hard work that requires a strong beak and neck, and the eaglets have a lot of growing to do before they can manage that on their own.

Special Treat:

Finally as a special treat, one of our cam watchers from Amsterdam, Netherlands, has put together a special "Day in the Life" movie showing images taken from our Eagle Cam during a 24-hour period. The movie is run at high-speed so you can see the entire day and night in about a minute, and you get a great look at how the mother moves in the nest. Download the movie by right-clicking on the link below and choosing "Save Target As." The AVI movie is 4.7 MB in size. Much thanks to Evert for sharing his creation!

Day in the Life of the Eagle Cam

[Note: If you have trouble viewing the AVI file, you can download this WMV file instead.]

In the next few web logs we'll talk more about food delivery, chick competition, and the possible gender of the chicks. And for those who are new to our cams, later in the season we will hold our annual chick-naming contest.

A Technical Note for AOL Users:

One of our cam watchers who uses AOL mentioned that when she visited the Gallery, she could not see the new pages I had added. AOL stores web pages on proxy servers to make websites load faster. A drawback to this practice is that sometimes you are not loading the newest page when you visit a website. If you think a web page is old, hold down the CTRL key and then click the Reload button in the AOL browser and this will force the AOL server to get the freshest page. This technique appears to work for AOL users who have tried it.

Until next time,
Lisa - webmaster
(contact)

Posted by Webmaster at 05:35 PM

February 22, 2006

First Eaglet

Much congrats to the eagle parents! We have our first eaglet, and from what we can tell it began hatching early this morning (a 36-day incubation). Since the first egg was fertile, it increases the likelihood that the second egg will be fertile as well.

first eagletThe eagle parents were really on the ball this morning. The mother was doing her best to shield the hatching chick from the rain, while the father suddenly became the ultimate provider, immediately bringing two good-sized fish to the nest as soon as he knew that the chick was coming. He also brought some extra grass to keep the family warm.

Eagle biologists have reported that the parents bring the same amount of food throughout the chicks' lives in the nest. This means that much of the food in these early days is wasted because the little chicks can't eat it all. But when the eaglets are grown, every bit of food that is delivered will be quickly gobbled up.

As for the new hatchling, when the chick first enters the world, its eyes are closed and its down is wet, but very quickly its eyes will open and its fuzzy down will dry out. Here you can see a close-up photo that shows what a dry, newly born eaglet looks like. You can also see its egg tooth in this shot.

A newborn cannot regulate its own body temperature in the first couple weeks, so it will be up to the female to keep the eaglet safe from the sun, cold temperatures, and precipitation. She may also put grass on top of the chick to keep it safe from the elements.

Also in the first few weeks, the female will be the only one tending to the chick, and the male will do all the hunting. But as the chick gets bigger, the female and male will take turns watching the eaglet and hunting for food.

According to eagle biologists, an American bald eaglet's rate of growth is faster than any other North American bird. A chick weighs about 3-4 ounces at birth but will grow to 9-15 pounds in about 3 months. The chick will stay in the nest for about 10-12 weeks, at the end of which it will begin flying. The fledgling will then spend about 6 more weeks around the nest before it becomes independent.

The health and growth of a chick is directly tied to the parents' skill at providing meals and to the health of the local fish and waterfowl population. The healthier the local food supply, the better for the growing eaglet.


Technical Notes:

I also wanted to make a quick mention of a couple technical issues, especially for our new cam watchers.

During the day I might update the message above the cam image. Today I was updating it a lot because things were happening quickly. If you have the cam page up for a long period, you might not notice that I've changed the message. But a way to fix that is to occasionally refresh the cam page, then you should see the new message. If you're using AOL or another ISP that stores web pages, you might have to click CTRL + Refresh to get the new page.

On another topic: Yesterday we had some minor image delays. The problem mainly affected the Friends' cam and not the cam at our partner website, WildCam.com.

If there is ever a problem with the Friends' cam, you can go to WildCam.com, and see if the cam is working there because the images on both cams are identical. You have to register on the WildCam site (it's free) but sometimes they are up while we're down, or vice versa. If the problem is related to our ground equipment, then both cams are likely to be inactive, but if it's a network or computer problem, then it might just affect one of the sites and not the other.

We'll update the Gallery tomorrow; thanks to everyone for their photos of the hatching.

Until next time,
Lisa - webmaster
(contact)

Posted by Webmaster at 06:37 PM

February 14, 2006

The Hatching Process

Nest Update: It looks like the eagle family and our cam equipment made it through the snowstorm in good shape. Fortunately the total snow accumulation around the refuge was not as high as was originally predicted.

parent and eggsSeveral cam watchers wrote in to ask why the female eagle was holding out her wings while sitting on the nest during the storm. From what we could tell, it seemed the female was attempting to keep a larger area of the nest snow-free. And if you look at these two photos, you can see that it worked.

When the smaller male exchanged places with her on the nest and sat on the eggs with his wings tucked in, you could see how little an area he was covering compared to the female. The female -- with her larger body and bent wings -- managed to keep the center of the nest from accumulating too much snow.

Hatching Time

We're now getting close to the hatching dates. Based on a 35-day incubation period, we calculated that we should see hatching around Feb. 21 and 23. A sign that something is happening is if we see the female off the eggs and looking down at them. Chicks will move within the egg and call out as they're beginning to hatch, so the parents will know ahead of time that an eaglet is coming.

A while back I mentioned that we would talk about what is inside the eggs. If you looked inside a healthy chicken egg you'd see these components. The membranes help keep bacteria out, and the yolk holds the germinal disc with the female's genetic material. And at the blunt end of the egg you can see the small air sac.

2005 hatchWhen the chick is ready to hatch, it will pierce the air sac and start breathing air for the first time. Then it will use its egg tooth (on the tip of its beak) to chip away at the shell. The chick will frequently stop to rest -- since breaking free is very tiring and its lungs have to get used to fresh air -- then it will change position and continue cutting away until it has cut through the top end of the shell and is able to kick out the bottom section. This process could take 24 hours. Once the chick is out, it will not have to be fed right away because before it hatches, it absorbs the yolk and uses that for early nourishment.

The eggshells themselves are composed of calcium carbonate with thousands of tiny pores. The pores allow oxygen to enter the shell and also allow carbon dioxide and water to exit the shell. This is an important process because if too much carbon dioxide builds up inside the egg, the chick cannot survive.

Candling is a method frequently used to examine the contents of eggs before they hatch. If the eggshell is not heavily marked, a person can hold a light up to the egg and reveal the contents. On the Northern Prairie Wildlife Research Center website you can see photos of bird eggs that have been candled during the development of the chicks. The interesting thing to note when looking at the photos is how at the end of the incubation period, the chick is so large it almost fills the egg, except for the air sac at the top.

This year our camera is farther away from the nest, so our view of the hatching will be a little less detailed. The reason we moved the cam higher is so we would be able to see the eaglets when they are bigger and moving around the nest. But last year, we did have a super-close view of the hatching, so if you're new to our Eagle Cam, be sure to visit the 2005 Gallery to see the hatching photos. It will give you a good idea as to what we hope to see around the third week of February. If you look closely at the first few photos, you can see the first small hole that the chick has made to break out of the shell.

Until next time,
Lisa - webmaster
(contact)

Posted by Webmaster at 07:47 PM

February 09, 2006

Cam Update & Bird Count

Cam Update: We apologize for our recent downtime. We have various pieces of equipment in the field that allow us to beam the images from the tree to the Visitor Center and then to the Internet. And keeping that field equipment in working order is a challenge, because the items are exposed to the elements and can suddenly fail. When something does go down, it can take time to locate the exact problem. Since the Osprey Cam had been getting very quiet, we decided to shut it down until March and borrow some of the newer equipment from the platform. We’ll have it back up when the ospreys return around mid-March.

The Great Backyard Bird Count:

As I mentioned in our last post, at Blackwater Refuge we conduct a mid-winter eagle survey each year to keep an eye on our eagle populations. But there is another kind of mid-winter bird survey where anyone can participate just by observing birds in their local neighborhood.

gbbcOn Feb. 17-20 is the Great Backyard Bird Count, which is described on the official website as “an annual four-day event that engages bird watchers of all levels in counting birds and reporting their results to create a mid-winter snapshot of the numbers, kinds, and distribution of birds across the continent. Participants count birds for as little or as long as they wish during the four-day period and tally the highest number of birds of each species that they see at any one time. At the Great Backyard Bird Count web site, they fill out an online checklist to submit their counts.

As the count progresses, anyone with Internet access can explore what is being reported from their own towns or anywhere in the United States and Canada. They can also see how this year's numbers compare with those from the eight previous years. Participants may also send in photographs of the birds they see. A selection of images is posted in the GBBC online photo gallery.”

chickadeeThe Great Backyard Bird Count is managed by the Cornell Lab of Ornithology and Audubon, and is a wonderful chance for adults and children alike to learn more about birds while adding to our general knowledge about the health of bird populations. The data that’s collected can help bird researchers learn about the impact of West Nile virus on bird species, learn if birds are expanding their ranges, or learn if there is an irruption of a particular species.

Irruptions are periodic incursions of birds into an area where they don’t normally appear. For example, this winter we are hearing of an irruption of snowy owls throughout North America. In fact, we saw a snowy owl not far from Blackwater Refuge a couple months ago, and the staff believes it might be the first seen in our county.

The power of the Great Backyard Bird Count is that by having so many people share their observations from their own hometowns, we get a better awareness of what is happening in the larger environment. Visit the Great Backyard Bird Count if you’d like to learn more about the event, get an observation form, view the gallery, or just see the results submitted by people in your home area.

Until next time,
Lisa - webmaster
(contact)


Posted by Webmaster at 07:53 PM

February 05, 2006

Photos and Survey

Nest Update: The eagles got a little rain at the end of the month, but altogether January was mild for them with no snow and above normal temperatures. We'll have to see if February brings more winter-like weather to the region. Just a reminder: We expect the eggs to hatch around February 21 and 23.

stareThanks to everyone for the Gallery shots this week. We had a couple photos where we clearly saw the sitting parent removing oil from the gland at the base of their tail. The oil is put on the feathers for waterproofing and cleaning.

Also we saw nice shots of the nest cup. It's interesting to see how the eagles have made a nest within a nest, where the nest cup creates a little protected area for the eggs inside their bigger home.

As for sequence shots, we saw an interesting pair of photos where it looked like one adult put grass on the other, then the sitting parent got up off the eggs and the other parent started putting the grass around the nest cup. And in another pair of photos we saw the eagles doing a little nest building at night. What was interesting is that eagles do not have superior night vision, yet they were rearranging sticks when it was dark and there was almost no light from the moon.


2006 Mid-Winter Eagle Survey

On a slightly different topic, last month 26 volunteers and 8 Fish and Wildlife Service employees contributed their time to help us successfully complete our 2006 Mid-Winter Eagle Survey at Blackwater Refuge. The mid-winter survey is something we do each year as part of a bigger survey of the eagle population in the Chesapeake Bay region. Here are the numbers from Blackwater Refuge --

Non-Roost Count AM
Bald Eagles
Immature: 48
Mature: 62

Golden Eagles:
Mature: 2

Unknown: 17
Total: 129

Top spot was our Wildlife Drive with 23 eagles. Golden eagles were sighted at the Wildlife Drive and Shorter's Wharf


Roost Count AM
Bald Eagles
Immature: 35
Mature: 52

Golden Eagles: 0

Unknown: 20
Total: 107

Top spot was Rte 335 Bridge with 44 eagles. Non-roost count numbers were slightly higher this year. Roost count numbers were slightly lower this year. [Note that weather conditions can influence how many eagles are seen during the survey times.]

So if you get to visit the Refuge during the winter, remember that the Wildlife Drive and the Rte 335 Bridge are good places to spot eagles. If you're really lucky, you might even get to see the rarer Golden Eagle.

Until next time,
Lisa - webmaster
(contact)

Posted by Webmaster at 09:55 AM