Osprey Cam Web Log 2005

The Fishing Expert

Nest Update: Each day the oldest chick is getting closer to its first flight, as we're seeing more photos of the oldest getting some air under its wings. At this point, the chick has to be careful that a strong wind doesn't take it off the platform prematurely. Sometimes a powerful breeze can send a practicing chick into its first flight whether it wants to go or not.

Also, the father osprey is back to his erratic food deliveries. The other evening, one of the chicks made it known to mom that it was hungry and tired of waiting on dad. The mother osprey left the nest and within fifteen minutes returned with dinner.

And yesterday we saw the oldest chick commandeering a fish piece for itself, after which the mother osprey retrieved a smaller fish and fed the youngest with it. Seems the mother osprey is still doing a fine job of making sure the youngest gets fed.

And speaking of fishing for dinner, the post below takes a good look at what makes an osprey such a fishing expert...

Ospreys are admired by many people who love birds, and one of the things birdwatchers find most compelling about the osprey is its fishing ability. Ospreys are considered to be one of the greatest fishermen nature has ever witnessed.

Everything about the osprey is geared towards making it an efficient predator of fish. The osprey's feathers are oily to reduce water absorption. Their legs have few feathers so they can dry quickly after a hunt. They have the distinction of being the only hawk with a reversible toe that lets them hold a slippery fish with two toes in back and two toes in front. Their feet are covered with small barbs -- or spicules -- that help them hold onto a thrashing fish. They have long slitted nostrils that can close when entering the water. And their vision is typical of a hawk in that it's sharp and powerful, but with the added advantage of being able to judge the location of fish as they move under the surface of water, which refracts light and distorts the fish's exact location.

Ospreys are, in fact, our only bird of prey that dives into the water for fish. On occasion ospreys will scoop fish from the surface like eagles, but the majority of time they will fly and hover above the water, and then when a fish is spotted, plummet from as high as 200 feet, extending their feet in front of them right before they penetrate the water and drive their talons into the slippery prey. Once airborne again, ospreys will often position the fish headfirst in their talons to reduce aerodynamic drag.

Ospreys can reach a speed of almost 40 mph during their dives, and the average adult is successful about one out of every four attempts, although some have recorded success rates as high as 70-80%. Ospreys weigh less than four pounds and can catch a fish of almost equal size, but they will normally target a fish in the 14-22 ounces range.

The osprey will hunt for fish in both fresh and saltwater, making their selections based on size and accessibility from the surface, as ospreys can only dive about three feet under the water. The osprey is a connoisseur of live fish and is not normally a carrion eater. In the Chesapeake Bay region the osprey's food preferences include shallow-water fish such as carp, bullhead catfish, menhaden, perch, and gizzard shad.

Our young cam ospreys will soon be working on their fishing skills with the hope of becoming as accomplished as their parents. Ornithologists report that siblings will hunt together after fledging and will develop their hunting skills faster than single juveniles do, although by the time the juveniles head south, the single chicks will show no difference in hunting ability or success.

Below you'll find a link to our Osprey Fishing Slide Show, which gives our cam watchers a chance to see in detail what they can't see on our Osprey Cam -- how the osprey catches its meals. The photos are courtesy of Vince Rees, one of our talented cam watchers; much thanks to Vince for the loan of his wonderful photography.

Click on the link below to open the slide show window. Use the buttons to navigate through the 14 slides. If you have dial-up Internet access, the photos might take a few seconds to load. Watch for the little green "ready" light to see when each has loaded. At the end of the show, click Restart to watch it again (it will load more quickly on subsequent viewings). Close the window when you're done.

Osprey Fishing Slide Show

This is the first time we've used jClicker Slide Show to display sequential photos. If anyone has comments about its operation -- good or bad -- please feel free to share them.

Until next time,
Lisa - webmaster (contact)

The First Flight

Nest Update: First, the weather. The area is currently going through a nasty heat wave, and the mother osprey has been doing her best to shade the chicks. The heat index (what it actually feels like) for tomorrow is supposed to be almost 115 degrees, although it might be a little cooler near the water. From what we hear, the heat should lessen on Thursday, and we certainly hope so.

Also, we had some interesintg shots this week showing the chicks learning how to perform nest maintenance. At first the oldest started imitating mom by rearranging the sticks, then the youngest joined in. Nest upkeep will be an important skill in the future.

Now onto our topic of first flights...

The oldest chick is rapidly approaching his first flight. The normal fledging age is 48-59 days and our oldest is now 46 days old. Last year our first fledgling went at 50 days, so it shouldn't be long before the oldest takes the first big plunge.

Avian parents do not need to teach chicks to fly -- chicks fly instinctively. And it's important that the fledglings get in all the flying time they can because by the beginning of September, these young birds will be on their way to Central or South America for the winter -- an arduous journey that they will make alone.

At this point the osprey parents can't do much to help the young to fly, but they might try to encourage them by withholding food so the juveniles will want to get out of the nest to find something to eat.

As for the length of the first flight, the distance depends on the accessibility of nearby perches. The cam platform is tall and is not near anything to perch on (it's out there by itself in the marsh), so the first step off the platform is a big one. During the first early flights, the juvenile ospreys will likely either fly a hundred yards or more to the nearby trees or they will perch on the ground until they have the strength to fly back up to the nest.

The idea of a juvenile osprey striking out for the first time is an exciting notion, and famous ornithologist Arthur Cleveland Bent penned a wonderful description of an osprey's first flight in his book Life Histories of North American Birds of Prey:

"Finally, confidence in the power of its wings, or the example set by its parents, prompts the boldest of the young to make its first real flight away from the nest, a supreme moment in its life. With surprising ease it sails or flaps along, but it soon becomes tired and looks for a place to perch. Its attempts to alight on a treetop are awkward and uncertain; it has not learned to grasp a slender perch and finds it difficult to get its balance with much flapping of wings and wiggling of tail. It may be forced to alight on the ground to rest...Such flights are short at first and the young always seem glad to return to the firm flat top of the nest, which will be their headquarters, bedroom, and dining room for several weeks yet."

Landing is, no doubt, a difficult skill to master for any young raptor, and many of the juveniles make some very ugly landings before they get the hang of it. Last year, one of our fledglings accidentally landed on momma.

As for fishing, it can take the juveniles a couple weeks to become skilled at catching their own meals (some juveniles do it in only 2-3 days), but the parents will be there with food even if the young have difficulty snagging their own dinner.

It's interesting to note that while juvenile ospreys are flying about, they will sometimes land on a neighboring osprey nest. We have quite a few osprey nests at the Refuge (several visible from the Wildlife Drive), and last year we even had a wandering juvenile land on our cam platform. The mother osprey looked a tad surprised to suddenly see an extra chick in the nest, but adults usually tolerate such inexperienced visitors -- and some have even been observed feeding them! Kind of like "Trick-or-Treat" in the osprey world.

In the next web log we'll post a slide show that illustrates how ospreys dive to catch their meals.

Until next time,
Lisa - webmaster

Chicks and Gender

Nest Update: Some interesting things to highlight. The ospreys watched a big set of clouds go over the Refuge the other day -- it almost looked like the Refuge was being invaded by a spaceship. :-)

Also, today we saw the oldest chick get his talons off the nest in a flapping exercise. The oldest is probably about a week away from flying, although it could be sooner. He might make some short hover flights over the nest before he actually strikes out.

And the mother osprey has been doing a good job of occasionally positioning herself between the two chicks during feeding time to ensure both get fed. Sometimes she even flies over to the youngest with her food so that he is sure to get some. A good mom.

We’ll update the Gallery on Tuesday. And now onto the topic of gender…

One topic that is always interesting is the possible gender of the chicks. As we said in our posting for the Chick-Naming Contest (don't forget the contest ends on 7/31), we don't know the gender of the cam chicks. But of course that doesn't mean we wouldn't like to know.

Naturally we look for clues. The first reliable sign of gender in ospreys is the “necklace” -- the coloring that an osprey has across their white chest. In adults, this is normally a rather reliable indication of sex (not 100%, but pretty darn good). If the adult osprey has coloring across its chest -- a "necklace" -- then it’s usually female. If the adult osprey has a completely white chest, then it’s usually male.

Of the two pairs we've had on the cam platform, both females had necklaces and both males had white chests (2004 couple, 2005 couple). The one noticeable difference between the two couples was that the two females had different looking necklaces -- one had a very dark necklace and the other had a very light necklace.

In the chicks, necklaces can be deceiving. Many chicks start out with a necklace and then lose it as they mature, so normally necklaces in young ospreys are not very reliable indicators of gender. If the young osprey comes back from South America in a few years when it has matured and it still has the necklace, then that would be an excellent sign that it was a female.

Body size is another indicator of gender in grown ospreys, but again it can be deceiving in chicks. With adult birds, the female is always bigger -- as much as 1/3 bigger. But with chicks, so many things influence their size at this stage, that it's hard to use it as a tool for determining their sex.

A good example of this difficulty can be seen in a batch of osprey chicks that were recently banded in southern Michigan. The website for the Osprey Watch of Southeast Michigan mentions that last month they went up to band five chicks, and they put female bands on all the chicks based on how big their feet were. While they were there, they also took DNA samples, and when the DNA tests came back, they found out that three of the birds had turned out to be male.

Putting the bigger bands on the chicks didn’t cause any problems, but based solely on size, the banders thought they looked female. So size at that stage (4-5 weeks old) was not a great indicator. Order of birth, amount of food received, and other issues can affect the size of a chick, and those factors can make it hard to determine the correct gender just by looking at the bird’s size. Of course, once the birds are fully grown (around the time they’re ready to migrate), size becomes a better indicator.

But for now, it appears that DNA tests are the most reliable way to find out the sex of the chicks, and since we aren't going to climb the platform to take blood samples from the birds, we won't know for sure what sex they are; but of course it's fun to guess. Once the chicks are close to migration, they will be almost fully grown, so maybe then we can look at both their size and their necklaces and make a good educated guess as to what their gender is.

Until next time,
Lisa - webmaster

Questions Answered

First, I wanted to thank everyone again for their support of our first Eagle Cam. As many have seen, this week we shut the cam down for the season, and we also added a few final shots to the Gallery, so you can see the last bit of action at the nest. We feel incredibly lucky to have had all three eaglets hatch and successfully fledge. It was an amazing season -- kudos to the outstanding parents!

Also, I thought it would be a good idea to post answers to several frequently asked questions that we've received about the ospreys.

A chick question: Why does the youngest chick look so limp?

Both chicks have been pretty docile recently because of the weather. We're in the midst of the worst part of a Washington, DC-area summer with lots of heat and humidity. The heat index this week has been around 100 degrees every day, so the chicks have been spending a lot of time lying around and hiding from the sun.

We did notice this week that the father osprey was at the nest more (possibly bringing more fish). At the same time the oldest chick was occasionally letting the youngest eat with him. Does this mean that the oldest chick is less aggressive when dad brings more food? Very likely, and hopefully it will continue.

A fish question: Why do the chicks need help tearing up fish at meal time?

Fish skin is tough, and ripping into it requires a good bit of neck and beak power. It takes awhile before chicks are strong enough to rip off bite-size pieces themselves.

If you'd like to see the tearing process up close, check out a video clip on this Finland documentary website. The filmmakers' movie clip (the 3MB sample is higher quality) shows a mother osprey feeding her young. Notice how she has to twist her neck to tear up the fish, and also notice that you can see her nictitating membrane (or third eyelid) come down to protect her eye as she tears into the meal. Also, in the background of the first feeding shot, look for the one chick just coming out of its egg. Wonderful clip!

A banding question: Will you band the osprey chicks?

At Blackwater National Wildlife Refuge we do not normally band birds. In the past it was done when the raptor populations were in serious decline, but banding is not done now. The only reason the eaglets from the Eagle Cam were banded is because Craig Koppie, from the U.S. Fish and Wildlife Service, went up to remove the one eaglet. It was decided that while he was there, he might as well band the eaglets. The Vermont eaglet would certainly have been banded when she was moved out of state, but Craig took the liberty of banding all three while he was in the nest. Right now, no one from the Fish and Wildlife Service has plans to visit the osprey platform, so we will not be banding the chicks.

A perching question: Why doesn't the father osprey stay at the nest?

Based on the actions of both the eagles and ospreys, it appears that the adults don't like hanging out at the nest unless they have to. If you remember, the eagle and osprey females did not start spending the night at their nests until right before their first eggs were laid. Before that the females would sleep in the nearby trees with the males.

The father osprey seems to stay at the nest for only brief periods of time while preferring to perch in other places. Some biologists believe that the males like to perch closer to their food source, while others have speculated that the males just don't like being around all the chaotic nest activity and begging chicks.

A former osprey pair question: What happened to the pair of ospreys that were formerly at the platform nest?

We've run the Osprey Cam for five years now, and in the first four years we had another pair on the nest. Our original pair returned in March and began rebuilding the cam platform nest only to suddenly up and move to a newly installed platform located nearby. We're not sure why they did that (they were very productive at the cam platform) but the other nest site appealed to them more. The folks who observe the Refuge ospreys just reported that it appears the old pair did not produce any chicks this year. It's likely the late move threw them off. Some years a couple just doesn't produce, but there is no reason why they can't try again next year.

And finally, we've had a few questions about building and locating an osprey platform. For those who want to know more about this topic, be sure to visit our previous web log post that points to several websites that offer construction plans. It's also a good idea to email your state department of natural resources as they might have important information on building and locating an osprey platform in your neighborhood.

Thanks for your questions!

Until next time,
Lisa - webmaster

West Nile Virus

Now that we're in the midst of prime mosquito season throughout the U.S., it's likely cam watchers have been hearing reports about the West Nile virus. As many know, the WNV infects mosquitoes after they feed on infected birds, and once mosquitoes are infected, they can then transmit the West Nile virus to humans, animals, and other birds while biting to take blood.

Despite the extensive media coverage that is often given to the West Nile virus, the reality is that the virus does not present a large threat to people here in America. In areas where the virus exists, a small number of mosquitoes carry it, and of those humans who do become infected, only about 1% become seriously ill. To illustrate, the Centers for Disease Control reported that in 2004 approximately 100 people died from WNV in the U.S., which is about the same amount as died from reactions to bee stings. This does not mean, however, that the virus should be taken lightly, especially by those who are the most susceptible, such as the elderly, the very young, and those who have a weakened immune system.

As it stands now, however, the West Nile virus is hitting bird populations the hardest. Since 1999, WNV has been detected in over 225 wild and captive bird species in the U.S., as birds are the natural hosts of the virus, and over 12,000 have died as a result (although death estimates are likely underestimated because many birds die of WNV and are never found).

Crows and jays were originally the most affected, but soon it was discovered that raptors (especially in the Midwest) were becoming victims as well. Among the raptors that were hardest hit were great horned owls, which are one of the few birds of prey that will eat crows.

Infected bald eagles and ospreys have also been discovered, and some have died from the virus, but the deaths have not been in huge numbers. Ospreys and bald eagles are aided by the fact that their main food source is fish, which lessens the likelihood that they will contract the virus from infected birds (although an added danger does exist because they use bird carcasses and body parts as nesting material).

Of special concern now are rare birds held in zoos, as well as the state of Hawaii, where the WNV has not established itself but represents a looming threat to the many unique and threatened birds living on the islands.

Blackwater Refuge is located in Maryland, and at this time the Maryland Department of Natural Resources reports that no infected ospreys have been found in the state, although they admit that significant testing has not been done (dead ospreys that are found can be tested to determine if the virus was possibly the cause of death). In Virginia -- our neighboring state -- the public state veterinarian reports that five dead ospreys were tested for the virus but all the birds tested negative.

Several research groups are currently working on a West Nile virus vaccine that can be used on birds. Presently there is a vaccine for horses that has been tried on captive birds, but the results have been mixed, so an avian vaccine is being researched at this time. A vaccine would be especially helpful for protecting captive birds that belong to endangered and threatened species rehabilitation programs.

In the wild, surviving birds seem to be developing an immunity to the virus. Over time this trend will likely grow as those birds that are resistant to the West Nile virus will give birth to a new generation and pass on these virus-resistant traits to their young.

As for humans, we can do more to reduce the local mosquito population by following some simple steps around the home, such as eliminating standing water in gutters and yard containers. If you'd like to learn more about the West Nile virus and prevention methods you can take, visit the Centers for Disease Control's West Nile Virus website to get more information.

Until next time,
Lisa - webmaster

Flapping Times

First, thanks to everyone for their photos from the last week -- we saw a lot of great shots. Also, a quick reminder that the Name the Chicks Competition is on until July 31.

During the week, some cam watchers had commented on the fact that the ospreys seemed to spend a lot of time on the edge of the nest. We're not sure why that was, but our cam technician did say that when he went out in his boat, the ospreys that he observed in other local nests were showing similar behavior. We think it might have had something to do with the hot, humid weather. Possibly the mother gets more breeze on the edge, and we know the chicks are using her for shade.

Domination continues to be the story between the two chicks. We've seen many shots where the youngest takes a submissive posture in response to the oldest chick's actions, especially during meal time. It's safe to say that the youngest will probably be the happiest chick in the world when the oldest learns to fly and leaves the nest to eat.

In the last two years of our Osprey Cam we had multiple chicks in each nest, but we never saw this dynamic where one chick aggressively asserted its "first-chick" privileges over a long period of time. In the past, both chicks fed together and neither was forced to wait for the other to finish. This year it's different.

What's especially interesting is that this year we have a new adult pair at the nest, so we have to wonder if it has anything to do with the parents. The father is seen regularly bringing fish, but earlier in the week we did see the mother go catch some fish herself on a couple of occasions. Then on one occasion when the father came back empty-taloned, the mother looked very unhappy about it. Maybe the father is spending too much time just sitting on his perch.

A new wrench was thrown into the situation early Sunday morning when a cam watcher caught one of the first shots of the oldest trying to eat a fish by itself -- indicating the oldest is getting close to being able to tear off fish without the mother's help. We're not sure how this will affect the youngest getting any food because the oldest isn't likely to share food that it wrestles away from the mother osprey.

The one visible penalty of the second chick's situation is that it's developing more slowly than the oldest. This means the youngest will fledge later than its sibling. Based on past fledglings at our cam nest, we expect the oldest to attempt its first flight in about two weeks. The oldest looks rather large and has been doing a lot of flapping, so its probably on target for leaving the nest. [Note that once the chicks fledge, they will still use the nest regularly for feeding, perching, and sleeping up until they migrate around the end of August].

Speaking of the flapping photos, we did see a cute set of photos where the chicks played Simon Says and showed off their flapping skills to each other.

Finally, another interesting behavior that we saw in the Gallery photos occurred on one afternoon when the father landed on the far side of the nest during dinner time. The youngest moved towards the father as if hoping he might provide some food, but the father looked on and did not have any food to offer. Later we saw the father drop off a fish for the two chicks when the mother was not in the nest, and the oldest chick made it clear that the fish was his, but the father did not attempt to feed the young.

At other osprey nests that have been observed, some fathers have shown a maternal instinct of sorts and taken to helping to beak-feed the young. So far our father is not one of those. I don't believe a study has ever been done regarding the tendency for father ospreys to help out, but it might be a behavior that is displayed by more experienced fathers, as opposed to new fathers, who only know that they have to provide fish for the family.

We want to thank all those who have been sending in their photos. The Gallery submissions have helped us learn a great deal about the osprey family and their behaviors, which -- as we've learned this year -- continue to offer surprises and new insights.

Until next time,
Lisa - webmaster

Cams and Squirrels

Nest News: We've been watching the relationship between the chicks since the sibling rivalry seemed to escalate beginning on Saturday. It now appears that they've reached an agreement of sorts whereby the oldest eats by himself until he's full, then the youngest is allowed to eat pretty much unmolested, while the oldest often moves to a different part of the nest.

We're still not sure what brought on the increased tension. It could be that the youngest forgot his place in the nest hierarchy or possibly the oldest was just flexing his size advantage. We still see some occasional aggression, but this new arrangement has been working for a couple days now, so hopefully it will bring some harmony back to the nest.

In other news, we've started seeing some great shots of the chicks discovering their wings. We'll update the Gallery over the weekend. Thanks to everyone for their photos.

And now onto a different camera topic...

The Osprey Cam and the Eagle Cam are the two main cams at Blackwater Refuge, as many of our cam watchers know, but there is another type of cam at work that I thought our viewers might enjoy knowing about.

While most folks assume that bald eagles are the most important animal at Blackwater, the fact is there is one animal that is even higher on the "celebrity" list than the eagle -- and that's the Delmarva fox squirrel.

The Delmarva fox squirrel has been a federally endangered animal since 1967, and Blackwater Refuge hosts the squirrel's largest remaining population. The "fox" part of the name comes from the squirrel's bushy tail that often reaches a length of 15 inches, and the word "Delmarva" is actually a combination of the three states that comprise the peninsula where Blackwater resides -- the states being Delaware, Maryland, and Virginia (Del-Mar-Va).

The Delmarva fox squirrel once ranged from southeastern Pennsylvania down through the Delmarva Peninsula, but the squirrel's population has declined mainly because of woodland conversion for agriculture and human development, as well as over-hunting. Translocated populations have been established throughout the Eastern Shore and at Chincoteague National Wildlife Refuge in Virginia, but Blackwater Refuge currently provides habitat and protection to the largest remaining natural population of Delmarva fox squirrels in the country.

For many people, it's a lot harder to see one of these squirrels than it is to see a bald eagle. I can personally attest to the fact that I saw an eagle on my very first trip to Blackwater, but went years before I saw a Delmarva fox squirrel. This endangered squirrel has a light, steel-gray coat and a large fluffy silvery tail with black edgings, and feeds more on the ground than the gray squirrel. The fox squirrel is also a good deal bigger, with Delmarvas reaching upwards of 30 inches in length (compared to a 20-inch gray squirrel).

At Blackwater efforts have been underway for some time to restore and manage the type of habitat favored by the squirrel -- mature pine and mixed pine-hardwood forests with little undergrowth. The refuge staff works hard to achieve the goal of one day removing the squirrel from the endangered species list.

But part of what makes it so difficult to help this squirrel is that it is very shy -- and that's where photomonitoring comes in. Photomonitoring uses hidden cameras that are triggered by the mammal's activity, and with the aid of these small cameras, biologists are learning more about what areas of the Delmarva Peninsula have the best quality habitat for the endangered squirrel. Visit the Chesapeake Bay Field Office website if you'd like to learn more about how cam technology is helping us help the animals.

Until next time,
Lisa - webmaster

Chick Aggression

First, we want to announce that we plan to start the Osprey Chick-Naming Contest in the next day or two. Again, it will he hosted by Wildcam.com. We'll post an official announcement on both sites when the contest goes live.

Just a side note -- although I sometimes refer to the chicks as "he" in the Web Log, at this time we cannot tell the gender of the chicks, and we won't know their gender before they leave for South America in late August.

As for nest news, starting Saturday, we noticed that the oldest chick has suddenly become much more aggressive towards the youngest chick. He has been moving towards the youngest in an attempt to intimidate him and prevent him from feeding, although it doesn't appear to be life-threatening and the youngest chick is still getting chances to feed.

We're not sure what caused this increase in aggression. Up until yesterday, the chicks were only exhibiting a small amount of sibling rivalry, but something changed. It's possible the youngest started it. Sometimes the youngest chick will decide he's tired of eating last and will become more aggressive himself. This will cause the oldest to attack the youngest to teach him a lesson about who is first.

The mother is not interfering with the fighting, as is normal, although Sunday morning she did try to move the food to the side of the nest where the youngest was so he could get his fair share, but the oldest chick would have none of that, and he went after the youngest again. Finally, on the second feeding, the youngest got to feed after the oldest was full.

Chick aggression can increase and decrease at different intervals, and since the youngest is healthy and strong, we are not overly concerned at this time. We hope that the aggression will diminish and the mother will continue to make an effort to get food to them both.

A couple cam watchers have asked if we would ever intervene, and the answer would be no. We treat our cam nests as if they are nests that we are not watching. Nature is allowed to play out as it normally would. The only times we would step in is if a chick fell out of the nest or if the nest itself was in any kind of danger of falling. Otherwise, nature goes on.

Again, we're hoping that the aggression will decrease and things will go about as before, where both chicks coexisted more calmly. As a reminder, they are now 4 weeks old and are only about 3 weeks from flying.

Until next time,
Lisa - webmaster

Feather Growth

First, I know that we have a lot of cam watchers from the U.K., so I just wanted to say how sorry those of us in the U.S. are for what occurred in London on Thursday, and we hope that all of our watchers, and their family and friends, are safe at this time.

We've updated the Gallery with lots of interesting photos that offer some insights into how the chicks are developing. I want to thank all those who took the time to send in such great shots. When you're looking through the latest updates, notice the back-to-back shots that sometimes show action in the nest. In several places we have two or three shots in a sequence that capture an interesting event.

If you look carefully at the Gallery, you can see that the oldest chick is often fed first. This is the way of life in a raptor nest. Fortunately, we don't see a lot of aggression between the chicks, and the mother osprey appears to feed the second chick regularly, as the youngest is growing big and often has a full crop.

We also see some shots providing confirmation that the chicks are beginning to stand up, as well as lift and exercise their wings. This activity will increase in the coming weeks as the chicks prepare for fledging, which could be less than a month away.

We can also see from the photos that the mother osprey still seems to be bothered by activity near the nest -- most likely the eagles. The chicks appear to obey her most of the time and stay down in the nest when she's gone.

Another interesting set of shots we received include a humorous -- although unfortunate -- sequence showing the mother osprey getting accidentally sprayed. Luckily her head wasn't up. :-)

Finally, we can see some good comparison photos that indicate that the oldest chick is ahead in his feather development. His downy fuzz is clearly being replaced by growing feathers.

Melanie Lynch, our friend from the Chesapeake Bay Magazine, kindly loaned us a pair of photos she recently took on an osprey banding trip, and the photos offer a terrific close-up view of two osprey chicks in varying stages of feather development.

In the photo on the left (click on the thumbnails) a younger chick is just starting to see his blood feathers or pin feathers develop. And on the right, a slightly older chick is seeing even more feather growth.

Feathers come from follicles (tiny bumps) that grow in rows or tracts on the bird's skin. When the feather first comes out, it is rolled and protected inside a tube-like sheath that contains blood vessels, which nourish the feather's growth. The bluish-coloring in the sheaths is blood; this is why they're called blood feathers. You can see the blue sheaths in both these photos.

Once the feather has developed and burst through the sheath, the protective tube will fall away or possibly the bird will pull it off while preening. The blood vessels will have withered and the quill will be the white color we are familiar with seeing.

Blood feathers are sensitive and if broken or injured, can cause severe bleeding and even death. When a blood feather is broken, it must be removed so the follicle can close and a new feather can be born.

Note that in the second photo featured above, the chick's feathers are not solid brown like an adult's, but instead have tan tips. Young ospreys have a tan coloring at the tips of their feathers that lasts until they are about eighteen months old. It is believed that when the young ospreys fledge, the tan coloring helps notify adults in the area that the birds are immature and not a threat to the adults.

Here is a wonderful photo of a young osprey chick from Martin National Wildlife Refuge in the Chesapeake Bay. The Blackwater Refuge staff oversees this refuge, which is popular with ospreys. The photo offers a close-up look at the tan and brown feathers of an immature osprey and shows what our young raptors will soon look like.

Until next time,
Lisa - webmaster

Morning with the Family

Nest News: We've had a lot of great close-up views of the chicks recently as they've been posing right in front of the camera.

In two of the recent photos, we saw perhaps our best comparison yet of an empty and full crop on the chicks. As a reminder, the crop is a sack on the upper chest where a bird stores food for later digestion. From the parents' point of view, the advantage of a crop is that it means they don't have to feed the chicks as often since the young birds are storing food in their crops. It's always a good sign to see a chick with a bulging crop because it means they're getting fed.

We'll update the Gallery in a few days with all the revealing shots. Now onto the videos...

On Sunday, July 2, I took an early morning trip around the Wildlife Drive to spy on the osprey family at the platform. Our gift store manager had told me that the chicks were now visible from the road that winds through the Refuge, so I took my video camera and went out to see what I could see. It was quite a morning.

The weather was perfect as it was sunny and calm, and after about twenty minutes on the paved Drive, I was lucky enough to have seen four adult bald eagles, three adult ospreys, six turkey vultures, two great white egrets, three great blue herons, four turtles, and a rabbit munching on some dewy grass by the road.

As I arrived at the Osprey Cam platform, I noticed that the mother osprey seemed agitated and appeared to be calling out. High in the air above the platform was the father osprey and an adult bald eagle. It seemed the eagle had come too close to the platform for comfort, and the father osprey was trying to escort him from the premises.

The eagle seemed to go quietly, so after performing his duty, the father osprey then flew off to find a fish for the family. However, after about ten minutes, two adult bald eagles flew back into the area, and landed in a group of trees about 100 yards to the left of the osprey platform.

The mother osprey started calling out again, but this time she was on her own as the father osprey was out of the area on his fishing trip. Not liking that now two eagles were in range, the mother osprey took matters into her own hands and left the chicks to fly toward the eagles.

Once she reached them, the mother osprey began a sequence of slow dives at the two eagles, making it clear that they were not welcome. She continued for about five minutes, then returned to the platform, where the two chicks were lying low. Once she returned, their little heads popped up so I could see they were in the nest. After watching the family for awhile, I saw one of the chicks give a mini flap of his wings -- a sure sign that they're beginning to exercise their appendages.

The mother osprey continued to stay with the chicks as they awaited the return of the father, but a short time later, she again noticed a bald eagle hanging out in the nearby trees, and so she left again to offer more intimidation. This time, however, the chicks stayed upright, so both could be seen together in the nest. After a few minutes, the mother came back and soon after the father arrived with a fish lunch.

All in all, it was a rewarding morning as I got to see the rapidly growing chicks, as well as a display of how the family works together to keep the little ones safe. The eagles kept them hopping, but the osprey parents did well.

By the way, all the eagles I saw were adults -- no sign of any young eaglets on this trip. As for the osprey chicks, they will need protecting for a little while longer, but soon they will be big enough to take care of themselves.

Below are several videos of the day's events. The clips are not highly detailed because I wanted to keep a safe distance from the ospreys so as not to upset them. These are Windows Media Player files (.wmv) and the file sizes are shown next to the links. Right-click on the links and choose "Save Target As" to download the clips to your hard drive.

1. One of the offending eagles that was hanging out in the trees near the platform (3.5MB)

2. The mother osprey dive bombing the eagles in the trees and then returning to her chicks (2.4MB)

3. Two chicks home alone for a short time as the mother osprey goes off on another eagle mission (1.6MB)

4. A small wing flap from one of the chicks (1MB)

Until next time,
Lisa - webmaster

Ospreys & their Bird Friends

Nest News: We apparently have another form of life living on the platform -- our annual spider has returned (although it's obviously a different spider). Every year we have a spider who manages to get out onto the tiny camera and weave a web around the lens. Fortunately, it's not visible during most of the day and neither is its web, but at night during the summer, it's very visible, as this photo testifies. It will likely be with us for a while, so we thought we'd warn you in case you wonder what that white stuff is on the lens. Unfortunately, ospreys don't eat spiders, so it's pretty safe there for now.

Speaking of ospreys and other wildlife, an interesting topic that we haven't mentioned in the web logs before is the relationship that ospreys have with the rest of the bird world. While we've looked at the often adversarial relationship that ospreys have with bald eagles, we haven't really mentioned the rest of the bird community.

Some sources (including one of our cam watchers) have testified to the fact that when fish are not readily available, ospreys will eat non-fish items such as ducklings, frogs, turtles, and even small mammals. Although ospreys are considered rather strict fish-eaters, there is evidence that they will broaden their diet if they must to survive.

But on the norm, ospreys are among the least threatening raptors in the avian world. In fact, there are quite a few bird species that are so comfortable around ospreys that they have been known to nest within the osprey's own nest or in its supporting structure.

A report that appeared in the Wilson Bulletin (an ornithological publication)* in 1994 discussed observations made during the 1991 and 1992 osprey breeding seasons in both Michigan and Ontario where other birds nested inside osprey homes. The scientists reported that in the Great Lakes basin, they found six species of small birds breeding within or immediately beneath occupied osprey nests. Breeding inside the nests were common grackles, tree swallows, European starlings, and house sparrows; and breeding in the structure supporting the nest were northern flickers and barn swallows.

The scientists reported that the ospreys laid eggs in all but one of these nests and they saw no hostility between the ospreys and their tenants. Also worth noting was that the frequency of the hitchhiker birds was higher at natural nest sites rather than at artificial platforms -- mainly because artificial platforms were often too shallow to provide space for additional birds.

So why did these tenant birds choose to nest in close proximity to such a powerful raptor? The scientists stated in their paper that the smaller birds probably benefited in several ways; first, the osprey nest made up for a lack of suitable nesting habitat in the area; second, the smaller birds benefited from a decreased risk of predation because the ospreys would attack any menacing crows, raptors, or mammals near the nest; and third, the smaller birds could eat the insects that were attracted to the fish remains in the nest.

As for the ospreys, they benefited from this symbiotic relationship by using the smaller birds as added security guards. The neighbor birds could sometimes see predators before the ospreys did and alert them to danger.

In addition to songbirds, other birds found nesting within osprey homes include smaller herons and ducks. Melanie Lynch, from Chesapeake Bay Magazine, recently went on an osprey banding trip on our local Patuxent River and took this photo of an osprey platform built atop a wood duck box (click on the thumbnail). Melanie said a wood duck flew out of the box before they reached it, so it appears it was active. Apparently the ducks did not have a problem living directly below a raptor family.

While all these reports make for enjoyable web-of-life stories, the fact is some small birds are not always welcome at an osprey nest. At the Woods Hole Oceanographic Institute's Osprey Cam, their current mother osprey has found a neighboring red-winged blackbird that likes to sit on her tail and make a nuisance of itself. You can see a photo of the pesky little bird here. It's likely that he's attracted to the insects at the nest, but the mother osprey must wonder why he feels compelled to sit on her tail and add to her troubles when she has three hungry chicks to raise. There's one in every group. :-)

Until next time,
Lisa - webmaster

* "Birds breeding in or beneath Osprey nests in the Great Lakes basin" Wilson Bull., 106(4), 1994, pp. 743-749