More insight by raptor expert regarding Osprey family near Nelson
By Contributor
Former Nelsonite William Dove was pleased to see Nelson Hydro and Columbia Wireless joined forces to have a camera at the nest of an Kootenay Osprey family just off Highway 3A west of Nelson by Grohman Park.
Dove, who got his start as a raptor rehabilitator, educator and falconer when I lived in Nelson about 35 years ago, decided to use his expertise to take The Nelson Daily readers through the hatching process as Ospreys played a big part in peaking my interest in raptors.
Dove went on to also breed many raptor species and assist in continuing the publics’ education of raptors in the school systems of B.C., Alberta and parts of the NWT.
He currently resides near Cranbrook where his work was featured in Beautiful B.C. magazine and the C.B.C.’s On the Road Again.
This is the second installment of Dove’s column. The first column can be read here.
See live stream.
The nesting Osprey family is 19 days from the laying of the first egg before viewers of the Osprey cam sponsored by Columbiawireless.ca and Nelson Hydro on May 3.
Osprey started incubation with the laying of this first egg which will result in the eggs that hatch doing so in the order they were laid. This is referred to as asynchronous hatching, rather that eggs that are laid but not incubated until the clutch is complete which is referred to as synchronous This results in the eggs hatching at about the same time.
A system common with waterfowl, as one example. With this nest the eggs were laid May 3, 6 and 9th and should hatch with approximately 3 days between them. Interestingly, often each egg laid by Osprey are slightly smaller that its predecessor so the hatching young will be those many days younger and smaller. This has strong implication in the struggle to survive. I will talk about this more in a later instalment.
Eggs are one of the truly natural wonders of the world. Many animals come from eggs: fish, amphibians, reptiles and birds. The latter two enclosed in hard shells. Eggs are a small habitat. Simply put all habitats require space, shelter, food and water. All these components are necessary and share equal importance.
The bird egg if viable (fertile) contains a developing embryo, a protective shell that breaths, fluid for more protection and cell construction, food in the form of a yolk and space to develop and grow.
As the egg is forming within the female it is fertilized by the male’s sperm well before the shell is formed. The shell in Ospreys is coloured with pigments while still in the oviduct and just prior to being laid. In Osprey the colors are often oranges and browns in various patterns which help the egg blend (camouflage) with many of the common vegetations used to create the nest bowl. This vegetation also acts as a insecticide and fungicide to help protect the eggs, young and adults.
With many wild birds the incubation period is uncertain because several outside forces effect that time period. Weather, quality of adult’s incubation, ambient temperature and humidity are some of those factors. If the egg is fertile it may hatch in approximately 33 to 43 days from Northern Hemisphere Osprey.
The hatching process is considered to begin with what is called pip. Although the embryo has broken into the air cell prior to pip. The air cell has increased significantly in size as the embryo has developed and moved closer to hatching.
The increasing in size of the air cell is called drawdown. The pip is achieved by the only tooth many birds will ever have, including Osprey. The egg tooth is a sharp projection on the upper beak (mandible) and with the aid of a special muscle in the back of the neck used to repeatedly lift the mandible to tap on the inner egg shell near the air cell end of the egg (normally the larger end) until the shell breaks to create a very small lifting of the shell.
This pip allows for a greater amount of air to enter the egg and help the embryo’s respiratory system further develop to handle breathing our air.
With all this effort the embryo is tired and will often rest. It may now take 24 or 72 hours for the embryo to hatch. To emerge from the egg the embryo must break the shell off much like we enter a soft boiled egg. We use a knife or spoon. The embryo will use it’s egg tooth. This is called breakup. Unaided by an adult, the egg tooth is used to crack the
shell from inside. You may have your favourite way to rotate the soft boiled egg you are cracking into but the embryo will turn within their egg so the crack moves counter-clockwise until they have completed the circle. They now will push the freed end away and emerge as an Osprey nestling.
Eagle’s young have a special name, eaglet: hawk’s young, hawklet; owls young, owlet but there is no special term for Osprey nestlings and young chickens are not called chicklets. So it is common to refer to them as young, nestlings, progeny but not really appropriate to call them chicks but it is often done. Babies is not appropriate either.
I realize this instalment got a little technical but hopefully not too boring. I highly recommend searching the Internet for video of egg development and hatching. There are lots there of raptor eggs hatching.
If you haven’t been watching the Osprey cam yet come join us and register in the chat to ask questions. We are hoping to start a specific session for children just before the eggs hatch which should begin around June 7th.
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