Will There Be A Fourth Egg?

Who can say? If Mariah were sticking to her “traditional” egg-laying schedule, we would have expected to see another one sometime in the afternoon. She is still looking fluffed up and even a little gravid, so it’s possible that she has another egg on the way. Since she’s clearly not keeping to her old pace, we’ll just have to wait and see.

I’ve consulted with some falcon experts and learned a couple of things. The first is that long egg-laying times are not quite as rare as the literature might seem to indicate. It happened at a couple of nests in Toronto, Canada, for example. In those cases, territorial disputes appear to have been the cause, but age, weather and external stresses can all cause egg laying to be delayed. The consensus seems to be that as female Peregrines get older the normal gap of 48 to 72 hours between eggs can stretch, sometimes quite a bit.

It is possible that Mariah laid an egg between the second and third ones that we see in the nest box. We don’t know of any alternate nest sites in the area though. Also, since laying the third egg (and even before) she has been exhibiting typical brooding behavior at the Kodak nest site. She’s also been here almost constantly, so if she did lay an egg elsewhere, it has almost certainly been abandoned.

Incubation shift change

In fact, Mariah and Kaver have both been spending a lot of time incubating the three eggs in the nest. The picture at the left, from earlier today, shows Kaver arriving at the nest to take over brooding from Mariah. In true falcon style though, Mariah has been doing most of the work, with Kaver taking over only for a couple of hours at a time. When he’s not taking his turn incubating the eggs, he stays near the nest. Usually he’s perched just outside the nest box.

Kaver incubating

This is a typical pose for Kaver when he’s brooding the eggs. Notice how he’s leaning a bit forward, with his tail up in the air? He sits that way so that he can get the brood patches on his breast in contact with the eggs. It’s the extra heat from the brood patches that causes the eggs to develop. If he just pressed his abdomen against the eggs he wouldn’t transfer enough heat for incubation to continue. So his posture is a clue to what’s going on in the nest.

So, keep your eyes on the Rochester Falconcam! Maybe Mariah’s on track to lay another egg, or maybe we’ll just have three this year. We’ll just have to keep watching and waiting for now.


10 Responses to “Will There Be A Fourth Egg?”

  1. Baerbel says:

    To answer your question, Jess: YES, there is a fourth egg – visible at 00:27am – not sure yet, when Mariah actually laid it, though. Thanks for all your updates!

  2. Pam in Troy, NY says:

    Jess, I just wanted to say that I really appreciate all your comments & explanations. Although I’ve been watching for a few years now, I’ve been learning even more from your journal posts. Thanks for all the helpful information! I check here every day.

  3. Miss Conklin says:

    And… just as I check on what you’ve learned… I see there ARE four eggs. What a great time for our class to be watching Mariah!

  4. DianeB says:

    I just love watching the falcons. I can pick out who’s who, and think they are both just beautiful. This is my first year watching, but will not be my last. It might be written elsewhere in Imprints, but if I may ask, how old is Mariah? Thank you for all your information, I have learned so much.

  5. Audrey (UK) says:

    YES!!! Number four has arrived…………!!!!!

  6. Carol P. says:

    Of course there will be and is! Last nite Mariah laid her 4th egg! :-)

  7. Jess says:

    Well, as everyone can see, Mariah did indeed lay her fourth egg!

    @Diane- No one knows for sure how old Mariah is, but we think she’s at least 12. We know that Peregrines generally reach sexual maturity at two years of age, and she laid her first eggs at the nest box in Rochester in 1998. If we assume her 1998 clutch was the first she ever laid, then we believe she’s at least 12 years old.

  8. Margaret says:

    I have been watching for years now but this is the best especially with the “Imprints” section. Thank you for all of this terrific information on the
    Mariah and Kaver and I can finally tell them apart. I hope we have quints this year! Awesome sight.

  9. yasmin says:

    hay everybody i hoope u can keep learning about this 2 cute birds and i am from school #28 and my teacher is mrs.andino who is a wonderful teacherwelbye and keep learning about this 2 birds even though there is a missing egg

  10. patty says:

    Where has kaver been, I havent seen him near the nest at all during the
    days since the babies were born