Osprey Nest Tour with Judy Wink
Great evening on 30 May for a boat ride around Kent Narrows with Judy Wink of the Chesapeake Bay Environmental Center. The ospreys were a bit late getting started with these nests this year. Only three of them were suspected of having young yet (no visual of the young).
Judy shared her knowledge of Ospreys as we moved from nest to nest. This is the Osprey Fact Sheet she provided when we boarded Tuna the Tide Charter Service fishing boat:
The return migration to the Chesapeake Bay Area occurs between March 1st and March 25th.
Chesapeake Bay nesting birds winter in Costa Rica and Panama based on the banding data.
Ospreys return to their same nest year after year.
While migrating ospreys will travel on the average of 260-280 kilometers per day.
While migrating they have a tendency to fly in the dark.
Once a territory is established, they remain attached to that territory. If the nest is destroyed, they will look for a suitable site, and build a new nest.
They are monogamous birds, and live approximately 20-25 years.
Ospreys become sexually mature between 3-4 years of age.
The birds are similar in plumage (extremely variable except for the black eyeliner), but are size dimorphic. Females is slightly larger than the male.
In the fall they migrate with order in that the young leave between August 15th - August 25th, the males leave next around August 20th-August 30th, and then the females between September 1st - September 15th.
The average clutch size is 2.3 eggs.
Ospreys are “determinate” layers in that they are genetically programmed to lay a specific amount of eggs.
The diet of the birds consists of 99.9% fish.
They carry the fish head-first to streamline the event.
During the first week after hatching, nestlings are fed a mix of partially digested fish (regurgitation by adults) and tiny pieces of fish flesh.
During the first week after hatching, nestlings are not 100% homeothermic, and require the parents (mainly the female) to brood them. This means to keep them underneath the adult for warmth.
Eggs are incubated for 33-36 days.
Chicks fledge between 56-69 days.
Ospreys have 4 toes with the outside toe being reversible. (Two toes front and two toes back).
Ospreys are either right-taloned or left-taloned (as in the case of many raptors).
The foot surface on the bottom of the foot is sand-paper like to hold slippery prey.
Ospreys clean their beaks by a behavior known as “bill-wipe.”
The “ruffle-shake” behavior is readily observed when ospreys are in air after contacting the water in catching or attempting to catch prey.
Conservation Note: Ospreys were endangered in the 1950’s (extirpated in historical areas) because of chemical pollution (especially DDT), but has since made a comeback through re-introduction.
CBEC
