Monday, April 18, 2011

Hatching approaches?

Hi All,
I wanted to update everyone quickly with a reminder that we expect the first falcon egg to hatch toward the end of this week. Last year the firs egg was laid on March 18th and the first egg hatched on April 23rd...that is our best estimate of a hatch date.

The birds have been so diligent I expect that we can anticipate a successful hatch. Please keep an eye on these birds and remind your friends that hatching is fast approaching.

All the Best,
Patrick Keenan
BioDiversity Research Institute

Thursday, April 7, 2011

Caring for eggs in 2011.

With all the excitement at the eagle’s nest, our very diligent peregrine parents have been nearly forgotten. What good parents they are! 'Mom' spends about 70% of the day on incubation duty. Generally, she will spend the night with the eggs while 'Dad' takes short turns during the day to give Mom a chance to hunt on her own. Whoever is on the nest will change position about every 30 minutes and may turn the eggs at that time. They turn them to ensure that they are equally heated and to ensure proper development of the embryo inside the egg. If the egg is not regularly turned there is a danger that the membranes surrounding the embryo will stick to one side of the egg. We also observe that the parents leave the eggs uncovered for short periods of time. This behavior also contributes to egg development by allowing increased oxygen to flow across the porous shells thus increasing the oxygen in the fluid inside of the egg.

Sometimes when the female returns to the nest she seems to be very anxious to kick dad off the nest and get back to business. Last week Thomas, a regular BRI Peregrinecam watcher, captured a great series of photographs showing the female returning to the nest. He posted these photos to BRI's online community.

Once back on the nest, ''Dad' or 'Mom' takes quite a bit of time settling back onto the eggs. You will see the parent with its tail in the air, working to settle its breast firmly on the eggs. Both the males and females lose feathers in the center of the breast to develop brood patches for incubation. The area becomes increasing vascular and swollen with fluid creating a surface that allows more efficient transfer of heat from the parent to the eggs. Generally the patch is not visible on peregrines because the remaining breast feathers in adjacent rows cover the area. If you have never seen a brood patch, go to Google Images and search for brood patches. Although I have not found an example of a peregrine brood patch there, there are many examples from other bird species. They are not a pretty sight but are interesting. Patrick first described them to me as looking like a large boil!

If you have questions about this pair or peregrines in general, please send them to us. We will do our best to answer them in the next blog.

Happy falcon watching,
Kate Rotroff
BRI Peregrinecam Ambassador

Thursday, March 31, 2011

Eggs, Eggs, Eggs!

What a very exciting week at BRI – four Peregrine Falcon eggs and, for the first time in two years, an egg at the eagle nest. Thank you to all the BRI Peregrinecam watchers on the online community for documenting each egg. You captured some amazing pictures of peregrine behavior.

This image of a nest exchange was posted to the BRI online community by Thomas.

This peregrine pair is very consistent. Two years in a row the female has produced her first egg on March 18th followed by three more eggs approximately 48 hours apart. This year the first arrived about 9:00 am. The second egg was laid about 3:00 pm on March 20th. The third and fourth eggs arrived in the early morningof March 23rd and March 25th.

Before each egg was laid, the female displayed typical egg laying behavior. She appeared to be somewhat agitated, laying down, standing up and laying down again as if trying to get comfortable. Peregrines, like all birds, can control each of their feathers and you rarely see them looking ruffled. Just before laying each egg, though, the female seemed to be sitting on her legs with her feathers puffed up.

As BRI Peregrinecam watchers have observed, the peregrines do not begin incubating the eggs consistently until the penultimate or last egg is laid. Last year many cam watchers were concerned that the eggs were left uncovered for long periods of time. I checked the weather for this week in 2010 found that temperatures during that week ranged from highs over 50 degrees to lows of 40 degrees. Perhaps last year’s warm temperatures explain why the adults did not spend long periods incubating the eggs until the last one was laid. This year the adults seem to be doing a fine job of protecting the eggs from this year’s cool temperatures (highs have been in the 40s with lows in the teens). Interestingly, early on in development eggs are relatively cold hardy and can withstand periods of exposure depending on the outdoor temperature. Later in the season as the embryo develops hot temperatures can pose a problem for embryo survival. One possible benefit of this peregrine pair's scrape location is that is well-protected from mid-day sun.

Now the wait begins. The eggs should hatch the week of April 27 (approximately 34 days after the last egg was laid). Let’s hope for another successful season for these wonderful birds.

Thanks for joining in the conversation and enjoying the BRI Peregrinecam. To keep up with daily activities please visit us in our online community by clicking here.

Happy falcon watching,
Kate Rotroff
BRI Peregrinecam Ambassador

Getting Ready For the Season!

Excitement is growing among Peregrinecam watchers and those of us at BRI as our resident pair of falcons are making frequent visits to the nesting box each day. During their visits they are displaying typical courting behavior, bowing to each other with heads low and tails held high, and touching beaks. There also has been much nest preparation which entails one of the falcons lying on its breast and pushing gravel, dirt, and small stones out of the way with its legs, creating a bowl-shaped depression, also part of the courting behavior.

The activity in the nest box is only part of the courtship display. Peregrines have elaborate aerial rituals including high circling, diving toward one another as well as aerial “kissing” (touching beaks) and exchanges of food in flight.

Will all this activity lead to laying eggs soon? In the past two years they have done so during the third week of March. So the time is coming. Keep your fingers crossed!

For those of you who are new to the Peregrinecam, Peregrine Falcons have been using this man-made nest site since 2007. They do not build nests. They choose inaccessible areas, high on cliffs or on man made structures, frequently near water. These high, rocky areas are called eyries. The actual nesting area is often called the scrape, referring to the scraping of the gravel to create a nesting bowl.

Peregrines are generally monogamous. The male in this pair has had two mates. A new female appeared last year. This probably indicates that the previous mate died. This pair overwinters in the area, unlike many peregrines that migrate south. The nest is located in southern Maine. The exact location is not share in order to protect the birds. BRI works closely with Maine Inland Fisheries and Wildlife in order to protect and study this pair.

Is there a way to tell the male and female apart? Not easily. Their markings are the same. There are only two features that differ in this pair - the male is banded and the female is heavier and longer than the male. Generally she is 15% to 20% longer and 40% to 50% heavier.

Question from the Peregrinecam community: Any word on the three fledgling from last year? This is one of those cases where it is likely good news that we have no news. There are only two scenarios that could confirm a sighting of the birds - if one was netted during migration or if one was found dead.

Enjoy the falcons,

Kate Rotroff

BRI Webcam Ambassador