First full day in the field...

My first full day in the field checking nests...some interesting observations. Overall, I visited 22 nests and found five nests with ospreys. There were a pair of birds on three nests and one bird on two nests. I saw extra ospreys flying around at two of those sites. I read three bands. Most lakes near the nests were still frozen. Many of you remember the saga last year of one male who was attending two nests, with three chicks in each. Today one of those nests had a new male. He was copulating with the female there tho I was unable to determine conclusively if she was the same female as last year. It remains to be seen what happens if the territorial male returns.  He may chase off this new male. I believe they sort of instinctively defend territories where they successfully reproduced. The female may have a say in the matter also as she might jump into the fray and help chase off the very male she has been copulating with, or she may stay out of it and let the males duke it out. Usually a territorial male can easily displace any other males who might try to take over. His  other nest was empty. Perhaps one of the females won't return. Perhaps that will solve the dilemma. Perhaps he won't return! There are many scenarios possible. I have seen males defend two nest sites even if they were only breeding at one...defending the other one against any other ospreys, only to use it as a perch. Ah the drama goes on. Still so much to learn!

They're back!

I received several reports of Ospreys back on their nests today! The warm front has carried some of our winged friends back home at last! I spent some time watching one of my old friends working on his nest this afternoon. So osprey season has officially begun!  We're off and flying...

2013 OSPREY PRODUCTION SUMMARY...

The year 2013 began as a very late and snowy spring for the Ospreys in
the 8 county metro area surrounding Minneapolis and St. Paul,
Minnesota. With so many lakes still frozen, many Ospreys did not
return to their nests as early as they did in 2012. We did receive
reports of Ospreys as early as March 20, but many did not arrive at
their nest sites until mid to late April. Once again there was a
significant increase in overall number of occupied nests. There were
105 nests which were occupied by a pair of adult ospreys. In
addition, there were three nests where ospreys were only seen briefly,
and two nests where only a single osprey was observed. Eggs were laid
in 94 nests (83 in 2012) and 70 of these nests had at least one chick
that was confirmed to have fledged successfully or survived to
fledging age (68 in 2012). There were two additional nests reported
that were not confirmed as successful. The mortality rate was high, 
with 33 nests that failed (20 in 2012). There are two distinct subcategories 
under failures; nests where a pair was present but no eggs were laid (9) and
nests where eggs were laid but they failed to successfully fledge a
single chick (22). There were two additional  nests, discovered late
in the season, where it was not known if eggs were laid or not, but
no chicks were observed.  Not laying eggs is considered to be a kind
of nest failure by other scientists. There were 146 chicks that were
known to have fledged successfully or survived to fledging age. (there
were two additional chicks reported that could not be confirmed).
There were two chicks which died / disappeared before banding time,
and 15 additional chicks which were known to have died between banding
time and fledging, or around fledging time.  Two additional adults
died or disappeared midseason.  There were 98 adult Ospreys identified by 
their bands. Three of these were from Iowa, one was from southern Ontario 
and one was from Wisconsin.
There were 22 new nesting territories (this does NOT count nesting
territories that have been active in the past, were unoccupied for one or
more years and then reoccupied) ; 15 where eggs were laid. One of
these nests was reported for the first time, although it had been
active for several years. Twelve of these new nests successfully
fledged chicks.  There were 15 banded Ospreys which were believed to
have bred successfully for the first time and their average age was 4
years old. (Average age of first successful breeding for males this
year was 4.1 years and for females it was 3.8 years).
The overall productivity of occupied nests which were successful
dropped this year to 67%  (77% in 2012, 70% in 2011, 73% in 2010, 67%
in 2009). The mean number of young fledged per successful nest was
2.08 (2.05 in 2012). The mean number of young fledged per active nest
was 1.55 (1.68 in 2012) and the mean number of young fledged per
occupied nest was 1.39 (1.59 in 2012).  These numbers reflect a drop
in overall productivity, with a slight rise in the number of chicks
per successful nest. 

I will post a new entry soon with an explanation of terms, and thoughts on research 
methods.

March 21, 2014

I am still doing final counts on my tabulations from 2013 to be SURE the numbers are accurate...meanwhile, as we wait for the birds, I know many of you are interested in the stories of specific ospreys. I find myself thinking of four ospreys in particular. One is the male who will be the oldest this year. Mr 79 who has nested for many years at the Arboretum (which now has a cam on it) will be 22 years old if he survived another migration. He has a history of being a late return to his territory. His mates have often beat him back and engaged in some extra pair copulation and he has had to chase off some other males. Last year he got a new, young female, but their nest failed. I am anxious to see if he makes it back. The second oldest male would be Mr B4. He would be 21 this year. He has been a reliable male, with several mates but this would be his 13th season with his mate, if they both survived. He is the last of the hacked birds from the reintroduction. He was translocated from northern MN and released at the Cedar lake hack site. He returned to MN when he was two years old and spent that summer hanging around the Medicine Lake hack site, where I was the hack site attendant. He then nested on Mooney lake in Wayzata in 1996, moved to a nest on the lights at Wayzata West Middle School in 2001, and then moved to a nest on private property on Robinsons Bay and has been there since 2004. The oldest female will be 20 this year and is nesting on the Lake Minnetonka Regional Park Cell tower where she has been since 2000. The other female that I am anxious to see is the female on the Edina nest who had some eye issues last year. I hope she could see well enough to care for herself and to survive another migration. She was hacked out in Iowa and will be 12 years old this year. Those of us who have been watching these birds for years grow very fond of our winged friends!

PS Hacking is a falconers term...it is a technique for slow release of non flighted birds. This population of ospreys is the result of reintroduction efforts. Nestling ospreys were collected in northern MN and translocated to several hack sites in the metro area. A hack box is a large box(6ft x 6ft) on scaffolding with hardware cloth on the outside to protect these non flighted chicks from predation and yet to allow them to see their new home territory. I was one of the hack site attendants who fed the chicks small pieces of fish twice a day until they developed enough to be ready for flight. We had several different methods for releasing them when they were ready. They flew and learned to fish while we continued to provide food for them until they naturally dispersed. They imprint on the area where they learned to fly and return when they are old enough to breed. So B4 is a bird who went thru that process and returned to nest and has produced 38 chicks.

Well osprey fans...here it is 2014 and we are preparing for another osprey season. I am working hard on last years report, making charts, tabulating results, checking and rechecking all my data to be sure it is accurate. Many of you may have seen the post on the MOUnet about an osprey seen in Sherburne NWR a few days ago! That is a very early return in any year, but especially this year with all the snow and frozen lakes. Surprise, surprise. I wonder what other surprises are in store  for us! We always need volunteers to help monitor all these nests (105) so email us you want to get more involved! More posts are coming about research methods and the 2013 numbers.

End of September

I checked a few nests today and there are still some ospreys around! I visited one nest that was empty but as I sat there I saw an osprey flying off in the distance, so I went searching for him. I could hear a juvenile food begging but could not spot him. I went back to the nest...still nothing there, so I started walking and listening and finally located the juvenile in a tree. I did not find an adult, but I believe there was one that the youngster was asking for food. I went to another nest on the other side of town and found a juvenile female on her nest, preening and snoozing in the lovely autumn sun. So here it is, Sept 29, and we still have some youngsters that are not ready to start their first migration. Interesting. I will keep you posted!

First day of fall...

It was a glorious morning here in Minnesota...high fifties, a crystal clear sky, light breeze. I began my day at the farmers market and then proceeded on to check some osprey nests. I visited several of the nests that had fledged rather late and still had juveniles on them four days ago. The first nest I visited produced no ospreys at all, where there had been two young females a few days ago. The next stop was a nest that had one juvenile present four days ago. No ospreys seen or heard there either...but there was a lot of human activity there which made me wonder if that was the cause for the empty nest. I decided to pop over to a nearby nest where I had seen one adult on the last visit...he was still there, perched on the edge of the nest with a fish. After about fifteen minutes he flew in circles above the nest, displaying the fish for any hungry youngsters to see. Sure enough, he scared up another osprey and they flew in circles together for a while before the adult returned to the nest. Oddly, the other osprey landed only briefly before disappearing completely. I was not able to identify the bird as a juvenile or adult. Then the adult male took off also. I moved my car for a different view of the area. I located the adult male in a tree with his fish, but could not locate the other osprey. I returned to the other empty nest...still no ospreys there. I later received two emails from osprey observers who said they did see ospreys back there in the afternoon. I visited another one of the very latest nests to fledge and found two youngsters in the area, both with a fish of their own, tho I could not locate any adults. So we do have a few ospreys lingering in the area, tho many nests are empty. Its amazing how mesmerizing it is to just watch an osprey eating a fish, when you know it is a sight you may not enjoy for many months. I soaked up the sun and the pleasure of watching my beloved ospreys on this lovely early fall day.