May 29...

Our earliest nesters may begin hatching this week so stay tuned for the news! When the chicks first hatch, we cannot see them as they do not stand up and move around much. We must watch the adults behaviors for clues. During incubation, the sitting  bird has its attention focused outward most of the time...watching other birds, snoozing, only occasionally poking around in the nest cup, rolling the eggs. When the chicks begin to pip the shell, the adults can become restless, looking down a lot, getting up to peek into the nest cup. Often when the male comes, they both stare into the nest. The female may sit a bit higher. The confirmation comes when the adults begin feeding the chicks, ripping small bits off the fish and offering it into the nest cup. To some people, brooding looks just like incubating...so we have to observe more closely to catch the subtle signs that the chicks have begun hatching. When you have been watching this miraculous event as many years as I have, the signs are quite clear. It still thrills me after all these years!

Non breeding pairs...

Well, I have not posted much in the past week. Incubation can be a boring time. I have used the time to try to get bands read...I have now identified 78 birds by their leg bands. There are a few left to go. Some are difficult to view,  some males are scarce and females are hunkered down. I keep trying to catch the changing of the guard, when the males bring a fish for the female and he takes over the incubation duties...but my timing is not always right. I have seen at least six pairs of ospreys in the past week that are STILL not incubating. We are sliding past the window of opportunity now. When you add up a 38-39 day incubation period, 7.5-8 weeks until they fledge and at least a few weeks to learn to fish on their own, independent of their parents, you can see that chicks which hatch late have a poor chance of being adequately prepared to undertake their first migration in September. I am curious about why some pairs have not laid eggs. Some may have paired up with a female that is not sexually mature and is therefore not receptive to copulation attempts. ( Many females are unbanded so we do not know their ages). There may be other reasons for not laying eggs too...weather, nest removal that required extensive rebuilding, and some reasons we may not fully understand. We expected this rapidly growing reintroduced population of ospreys to level off at some point, but had no idea how that might look. Perhaps we will  begin to see more non breeding pairs.  We call these pairs "housekeepers".

Friday, May 16

I can now say I have visited all known nests and read bands at most of them. There are a few birds that are testing my patience by keeping their legs hidden. They will not escape my prying eyes for long. I am happy that the two nests where males disappeared / died mid season last year have new banded males on them.  I have been trying to read a band on one male who apparently LOVES to incubate. He sits for long periods, with the female perched nearby. I waited and waited and waited the other day...and when he finally got up and flew away, he came back in less than a minute with a stick, and pushed the female out of the way so he could sit down again. So interesting. They are all unique. It won't be long before hatching begins on some of the early nests!
All you birders in the metro area, remember to keep watching for new nests and let me know about them so the research can be as complete as possible. 

Update for early May...

There are only a few nests that have not laid eggs now. In most cases it is because it is a new pair (one or both birds are new to the territory), or a nest was removed over the winter and had to be rebuilt. I am still seeing extra ospreys interacting at many nests. But this is normal since ospreys are semi colonial and our population is large enough for there to always be young birds around looking for a territory. I did observe a fairly aggressive attack a few days ago between two females...one of them had already laid eggs and I was worried that the eggs would be damaged by the attempts of one female to knock the other off the nest. Things did calm down when the male arrived...we will see if the eggs hatch.
As many of you know now the arboretum birds on the cam are incubating and have two eggs so far.
I spent some time watching a nest today where I still need to identify the male...but he would not get up from incubating! The female was walking around him and food begging for the 90 minutes I was there, trying to get him to stand up by getting very close and literally hollering in his face. Nope, he was comfortable. Some males really like to incubate, tho some seem nervous and can't wait for the female to take over. So interesting. I will have to try again to ID this male. The male who was on this nest earlier showed up at another nest so now I am wondering who this fellow is? I will figure it out. It's like putting the pieces of the puzzle together.

Friday, May 2, 2014

Another day in the field yesterday...met with one of the new volunteers and toured a few nests. I am trying to meet with new volunteers that would like to spend some time in the field with me, so let me know if you are one of those people who would like to do that!
Most nests are incubating now...a few are not. I am seeing fewer territorial fights. Things are oddly unsettled on a few nests. I observed one female who was dirty, muddy looking with a fish in her talons, and a male sitting next to her. When she flew off, he chased her, as if he was trying to get the fish! Hmmm. Not sure how that is going to work out. Some of the nests that are not yet sitting on eggs are the new couples...still working on the courtship thing, nest building. Even on nests that have been active in the past, there may be a new bird. They are still playing musical nests, so I am still running back and forth between nests to see who ended up winning the territory, re reading bands when necessary. New nests are popping up. Many bands read, but still many more to read. On some nests it takes so much patience...especially now that they are incubating. Males can be hard to find, females won't stand up and reveal their legs. Of course males incubate also, but the females don't go as far as males do when they are on their break...they are usually somewhere nearby. I always have trouble keeping up with correspondence this time of year...so forgive me if I forget to answer emails. Just remind me. It's important to get the data...keeping people posted is also important and I am doing my best, but it's a lot of work.

Empty nests?

I am getting a lot of emails telling me that there is something wrong on a nest, or that the birds are gone. When I visit those nests, I find they are incubating, very low in the nest. Sometimes they are very hard to see...I watch for a little movement between the sticks, a little flutter of a feather. Sometimes no head pops up...it's cold and it been raining a lot and they really can hunker down.
I also visited some nests I had not been to in about nine days. One nest, that was empty on that last visit, had a pair present that were incubating. I followed the male to a perch and read his band...hmmmm, he was on a totally different nest 9 days ago. He had been seen there several times, copulating with the female. So I go to the nest where I had seen him before...female incubating there also, but I could not find a male anywhere. It started to rain so I will have to return and find the male to ID him. Musical nests. I wonder about the paternity there! I just can't catch up this year, with all the nests, all the bands to read, all the mate swapping and nest swapping. And I have another job too...gotta earn some money to pay for all this gas!

Monogamous?????

I recently read on another website that Ospreys are monogamous and mate for life. This is a commonly held belief about Ospreys and people often ask me about this aspect of osprey behavior. I have  documented repeatedly that they are not monogamous and do not necessarily mate for life. A perfect example is our 21 year old male this year. He has been with the same mate for 13 years. This is the longest pair bond I have documented in this population of ospreys. He had at least one other  mate prior to this one. However,  I have observed this male engaging in many extra pair copulations. He was with another female during the early days of this season before his mate returned. One year I witnessed him copulating with three different females before his long term mate returned! And yet, they remain together year after year. They have been very successful, producing 26 chicks together!  This is why they stay together, the biological imperative and driving force is to reproduce. Several of their offspring have returned and nested successfully also. I have also documented many "divorces". I hate this term as it is a legal term which does not really apply to birds, but it refers to the situation when a mated pair of ospreys are still alive and well, but split up and mate with other partners at other nests. It almost always follows a failed breeding season. My earliest observation of extra pair copulation, which led to the published paper, was seeing a female copulating with a different male than her long term mate for at least a week, but then she returned to her old mate and nest to lay her eggs. He was probably seen as a good provider in a better territory. When the chicks were all predated that year, she left him the following year and mated with the "boyfriend" of the previous year.  I have observed several males and females this year who are on different nests, with different mates, than they were  last year. In all cases, their nests failed last year. Not all ospreys split after a failed season however. The flip side is that producing chicks successfully together creates a bond with the partner and the nest...but extra pair copulations still occurr when the opportunity arises!
I co authored a paper that included some of this research that was published in 2008 in the Journal of Raptor Research. As our population of Ospreys has increased, I am seeing more extra pair copulations and divorces. Hard for me to understand why anyone still believes they are monogamous! But it takes long term study, good field work, with banded birds to prove these behaviors. I am certain it occurs more than we think among  unbanded birds.