Hatching!

 Our first chicks have hatched! We watched those early signs that something was happening on Thursday and were finally able to confirm a feeding on Friday morning, May 26. This was our earliest pair to lay eggs this year so this opens the window for others to begin hatching. Our large population is quite spread out this year with a few nests that just laid eggs, while others will be hatching soon.

We have discovered 12 new nests so far and I expect there will be more. We are still searching for some birds that appeared on their nest but then disappeared….and also looking for some birds who had their nests on cell towers removed over the winter and with the altered towers now unnestable, we wonder where they went. In some cases ospreys were seen briefly but then disappeared.

As the population grows, behaviors change and we have seen some startling aggression at one nest where an intruder relentlessly attacked the residential pair for many weeks until they seem to have given up. They are seen occasionally but have given up on breeding efforts. In my 30 years of watching ospreys I have seen aggessive attacks between ospreys about four times…so it’s not a common occurance. Ospreys are semi colonial, so ospreys attract other ospreys and we routinely observe some circling, chirping, even chasing and footing each other….even an extra osprey landing on a nest…but most interactions are limited and not very aggressive.

Third egg on the Arb cam nest

 Third egg laid on the Arb cam nest…..shortly after 4 a.m. They did incubate thru the nite again so we will see what the outcome is. This egg may have the greatest chance of survival.

Finally….

 The Arb ospreys finally incubated thru the night last night. Time will tell if these eggs hatch. While we wait for that….believe it or not, our first nests will begin hatching next week! And I am still trying to get around to some nests for the first time…I remember the early days when there used to be a break for me between reading bands, getting incubation dates and hatching! No more…I just keep trying to gather the data constantly. I still have some far away nests, and difficult to access nests to check for the first time…. And a lot to recheck for incubation. Possibly several difficult bands to read. We are seeing some unusually aggressive fighting for territories and that leaves me sitting for long periods trying to figure it out, and to document feather patterns so we can differentiate between the territorial male and the intruder.

ok, so why am I here writing posts??? Off I go…..

Another bad night….

 Well, I see that the Arboretum cam ospreys left the two eggs unincubated for nearly four hours last night, when the temps were quite cool (40s). We will see what happens when and if a third egg is laid. Sometimes when eggs are laid later than the usual time, fewer eggs are laid. I am starting to feel like I am watching a slow motion train wreck….the nest not being repaired, the eagles, all the different females….I have never seen so many unfortunate circumstances lining up. Whats next? Will things normalize?

Second egg and third osprey!

 And it was a cool, rainy night. While this may be evidence of this behavioral strategy called delayed incubation….we have never seen this before on this nest. As I reviewed the tape from overnight not only did I see that a second egg was laid this morning…..a third osprey was trying to land several times. It was unbanded and I suspect its the former female who was too young to breed. She may still see this as “home” and tho she may not be very aggressive, she may still think this male should feed her.

One of the reasons I find this theory about delayed incubation odd in this circumstance, is that leaving eggs uncovered also leaves them very vulnerable to predation. In a situation where Eagles have shown themselves to be a threat earlier this year, it kind of has me scratching my head. BUT since we have seen different females here and this one arrived more recently, she might not be aware of the eagles. In fact, the reason for the sequential females may be related to the threat the eagles posed to earlier females. Since females are stuck on the nest more than males, they are more vulnerable to attacks from eagles or other predators.

It will be interesting to see if a second egg changes their nighttime incubation behavior. Photo is the extra unbanded osprey trying to land while the female is on the nest. ( this happened several times) I also periodically hear the male chirping which is a vocalization that is used when another osprey is in the territory. The female on the nest stood up and sent the message that the visitor should not land!

Hmmmmm

 hmmmmm. One of the nest monitors pointed out to me that the ospreys at the Arb were off their new egg a lot overnight last night…..see photos. I reviewed the tape and it is a bit concerning. Ospreys may be off the eggs for short periods without much harm….and there is a behavioral strategy called ”delayed incubation” in which they chose not to incubate eggs fully until subsequent eggs are laid. The result of this is that the eggs will hatch closer together, rather than hatching several days apart as they are laid several days apart. Of course we cant know what the ospreys are thinking or what is causing their behavior. Eggs can die from getting too cold also….but we will keep watching for more clues. Note the time stamps on the images….

Egg!

 Well there was an egg laid at the Arboretum cam nest today….which baffles me as I have seen the female refuse copulation SO many times. But when I looked closer….at the dorsal feather patterns, I see two different females!

Can you see the difference? I see many differences….but look at the area above the right eye ( from our perspective) at what I call the eye brow in the top photo…..there is a lot more white and very little dark between the eye and the top dark patch on the female who was there several weeks ago. The female that laid the egg today has much darker eyebrows, and less white between her eye and her dark top patch on top of her head. The dorsal pattern on top of her head is also a different shape. I also see the female we had earlier did not have a dark extension of her top patch almost down to her beak as the female who is there today does.

I am not sure when the females changed. I know I have seen three different unbanded females on the nest this season. And I know that one of them was refusing to copulate, and that is also the one who seemed to trigger defensive reactions from the male. I have been so busy with other situations, checking nests further away, finding new nests (8 so far), searching for missing birds and reading bands.

Time will tell what happens next….they have not brought many sticks to the nest, so what is there, mostly grasses and cornstalks, may just blow away when we have strong winds or a storm.

We also sadly lost another banded male. He was found on the ground and taken to TRC where he died….mostly likely from the severe internal injuries he had. He was a young male, probably breeding for the first time this year as we had not seen him in previous years. Every loss is heart breaking.

 

Lots of miles….

 What a week…..I have driven over 100 miles almost every day trying to catch up on all known nests. We have already found 7 new nests! We are also seeing increased aggression between opreys as competition for good nesting sites increases. We have one nest where an extra osprey has been particularly persistant in trying to take over a territory, causing much distress for several weeks now. He has even drawn blood on one of the territorial birds. I suspect the eggs have been damaged /destroyed by his unrelenting attacks. I am seeing extra ospreys at more nests this year which suggests an ever increasing population of ospreys in the metro.

I am becoming fairly sure that we will have no chicks or eggs on the Arboretum cam nest this year. Most breeding pairs copulate many times a day in this early phase of the breeding season. But copulation attempts are rarely seen and the female is unreceptive to the males attempts to fertilize eggs when he tries. I have not seen one successful copulation attempt. It may be subtle stuff to many viewers of the cam, but to me it’s quite clear there has not been any cloacal contact. The behaviors tell me that this female is too young to breed. This failure to breed and lay eggs is not related to the eagles, who have not been seen recently.

We have already had our first known mortality. A ten year old male who had bred successfully for many years at two different nest sites was found on the ground near a freeway and taken to TRC. His injuries were too severe so he had to be euthanized. I suspect he was hit by a car. Every loss is so heartbreaking…. especially when you have followed a particular bird thru his breeding life. This is a loss to the Osprey population to have a successful male die. He fledged 12 chicks in his life.

All my long hours in the field this time of year are sometimes rewarded by witnessing some interesting behaviors. Yesterday I was watching a nest that had a little, seasonal pond that developed nearby as a result of all the snowmelt. The male was circling around and plunging in to the pond to bath. He splashed his wings, ducked his head under the water and then took off, circled around and did it again….big splash, lots of wing shaking, water flying, head ducking and then he took off, circled around again and again. I watched this for at least 15 minutes before he went to a tree to preen and dry out. What a pleasure to observe his playful bathing!

I also want to send out a huge thanks to Stephanie Burley and Rick Endo for their generous donations! So deeply appreciated!

Arb osprey behaviors

 I have been watching the Arb cam….now that the eagle chasing, and nest defense have lightened up, I am watching the behaviors of these two ospreys. This is a new female and I am seeing some behavioral clues about all this. In this photo you can see the male turning his back on the female and drooping his wings and shaking them……( wish i had gotten a video) this is a typical defensive posture often seen with a new pair of ospreys. I am also seeing that when the male mounts the female for copulation, she is unreceptive. She does not lift her tail. This can be a clue that she is too young to breed, or that she is unsure of him as a mate. Sometimes females do this if what they want is a fish. For a male to deliver fish is a part of courtship and pair bonding. The female is perfectly capable of getting her own fish or she wouldnt have survived this far….but part of the test of whether this male will be a good mate, is for him to provide food for her. But when refusal to copulate is a continuing behavior, it often means she is just too young to lay eggs. Time will tell. But we certainly are seeing a series of stumbling blocks for these ospreys…..the eagles, the poor condition of the nest itself, and the issues surrounding this new female and her possible young age. They may just become what we call ” housekeepers”, staying together and just working on the nest and their pair bond. I will keep watching for changes in these behavioral clues….

just thought you all might be interested in what I see, with 30 years of experience observing behaviors and outcomes.