Virginia.gov

VDGIF/Norfolk Botanical Garden Eagle Cam: 02/01/2009 - 03/01/2009

The Virginia Department of Game and Inland Fisheries, in partnership with the Norfolk Botanical Garden and WVEC, is providing a rare glimpse into the life of two bald eagles and their offspring!

Friday, February 27, 2009

“When will they hatch?”

This is one of the most common question regarding the eagles at the Norfolk Botanical Garden. Typical bald eagle incubation lasts for 35 days which would put us on schedule for St. Patrick's Day - March 17th for the 1st egg to hatch. This pair has an established history of extended incubation however with the 1st egg typically hatching after 38 days (target date of March 20th).

Subsequent eggs may take just as long or hatch after a shorter time period. The eagles will often not begin full time incubation with the first or even second egg. Indeed the Norfolk Botanical Garden pair didn't really settle down and incubate consistently until after the third egg had been laid. This somewhat delayed incubation has the effect of slowing early embryo development helping to compress the time between hatch dates. This can be important as the third chick to hatch can be at a disadvantage compared to its larger siblings - who've had several days to feed and grow by the time it emerges. By slowing development of the first eggs the chicks may hatch more closely together

Monday, February 23, 2009

“Egg Test Results”

Eggs from 2008 shown next to a baseball for scale

The eggs that were removed from the nest last year were sent to the lab at the Virginia Institute of Marine Sciences for analysis of potential contaminants. It is important to note that there was no indication of any contamination in these eggs. This test was performed as part of an ongoing effort to assess the presence of contaminants in the environment and their possible effects on birds such as bald eagles.
The tests revealed that the levels of both PCB and DDE were well within acceptable toxicity levels for bald eagles. DDE is a product of the breakdown of the pesticide DDT. DDE persists in the environment for longer then DDT and can have similar effects on the eggs of birds exposed to high levels.
DDT was a commonly used agricultural pesticide and was responsible for crashes in the populations of many predatory birds, as it caused eggshell thinning and failures of nesting attempts. PCB is a chemical that had a wide variety of industrial usages. It entered the environment through improper disposal and leakages. PCB is highly toxic and can have a variety of effects on wildlife. DDT was largely banned in the United States in 1972. PCB production was banned in 1977 although some use continues in enclosed electrical equipment.
Both DDE and PCB persist in the environment and are especially problematic in aquatic ecosystems. The enter the food chain when consumed by micro-organisms and small invertebrates. These are eaten by larger animals as the contamination moves up the food chain, eventually accumulating in top level predators like bald eagles. At each stage of the food chain these chemicals become increasingly concentrated in a process called biomagnification.
Populations of both bald eagles and other fish eating birds like osprey have rebounded since DDT was banned, although in areas of high concentration lingering effects remain.

Wednesday, February 18, 2009

“Egg #3”

The bald eagles at the Norfolk Botanical Garden have done it again!

Sharp eyed viewers passed along info and video clips that show the female apparently laying an egg shortly after midnight on Feb. 17th. The third egg wasn't definitively seen until more then 36 hours later! With the cold weather the parents have been staying pretty tight on the eggs. The third egg is often hidden from view by the edge of nest. The fact that this pair has again laid a three egg clutch is remarkable, most nest contain only 2 eggs, and this is the 4th year in row that this pair has had a three egg clutch. As many remember the eagle that was transported to the Wildlife Center of Virginia last year hatched from the 3rd egg of the second clutch - unfortunately the previous two eggs from that clutch were broken.

The video below shows a brief glimpse of the egg at approximately 45 secs. into the video


video

Friday, February 13, 2009

“2nd Egg”

At approximately 5:05 pm on Friday Feb. 13th a second egg was laid at the Norfolk Botanical Garden. This blog will be updated with more detail as soon as possible.

Thursday, February 12, 2009

“Windy Day in Norfolk”


Like most of Hampton Roads the eagles at the Botanical Garden have been buffeted by strong winds today. While the eagles and their egg are riding out the wind just fine, the conditions have created some difficulties for the Eagle Cam. The rapid movement means that the computers encoding the stream and publishing it to web have to digest much more data. This can also create problems for the end user as the increased data requires more bandwidth and can create buffering problems.

The Eagle Cam network works on a "line of sight", meaning that each element of the network must be aligned to properly function. High winds can shift these elements out of alignment, creating problems with the feed.

Please be patient. Weather related issues like this are entirely out of our control and are part of watching this nest "in the wild". All of the partners involved with cam work diligently to ensure that the feed is working at its optimal level.
Keep watching as we see if a second egg is forthcoming.

Tuesday, February 10, 2009

“First Egg in Norfolk”

The first egg of this season's brood was laid this afternoon at approximately 4:10 pm. The female's hunched posture in the nest was an indication that something might be happening. Sure enough we caught a brief glimpse of the egg.

Eagle eggs average from 2.75-3 inches long and 2-2.2 inches wide. The eggs are round-oval and
white. The average incubation time for eagles is about 35 days, although this pair has a history of incubating a little longer (37 days). We'll look for additional eggs over the next few days. Two eggs is the most common clutch size, although 3 is a possibility.

Now that the first egg has been laid the female will spend much of her time incubating the egg, the male will occasionally take turns as well. Both adults have developed a brood patch. This is a featherless area of skin on the eagle's abdomen. The brood patch has many blood vessels and is highly sensitive. This area is used by the adults to keep the eggs warm during incubation. The female's brood patch is generally more extensive and well developed, as she will be doing most of the incubation. The eggs will be periodically turned. This helps to maintain an even temperature and more importantly prevents the developing embryo from adhering to the membrane inside the egg.

It is not uncommon for the eggs to be left unattended for periods of time; this is not a cause for alarm. The eggs are able to retain heat for a time without a parent incubating. Parents will sometimes cover the eggs when leaving them, although this may be more to reduce possible predation then to keep them warm.

Wednesday, February 04, 2009

“What's for Breakfast?”


The image above shows the female eagle dining in the nest. After consulting with a colleague in the DGIF Fisheries division the fish has been identified as a speckled trout (spotted seatrout) Cynoscion nebulosus. The black spots against silvery/grey skin are distinctive and allowed the identification to be made. (Picture courtesy of the Virginia Marine Resource Commission)

These are a marine fish commonly found in the Chesapeake Bay during warmer months. The bulk of these fish winter in warmer water, although some remain in area. In cold weather these fish may become very sluggish and flounder at the surface, becoming easy prey for an eagle. Winter-kill fish are also an important part of an eagle's diet and they commonly scavenge carrion along the water's edge

The eagles at the Botanical Garden have a varied diet (that commonly includes gulls) but rely heavily on fish. Previously we have been able to identify gizzard shad as one of their prey items. These fish are common in the freshwater of Lake Whitehurst adjacent to the Garden. The proximity of both fresh and marine water provides a great resource to these birds, allowing them to take advantage of many prey species. The continued recovery of bald eagle populations depends on healthy fisheries and on the health of the Chesapeake Bay and our lakes and rivers.
For more information on
Marine Fisheries: http://www.mrc.state.va.us/










“Eagle Cam is Live”



The Eagle Cam is officially live as of February4th! The cam feed has been available at WVEC.com for some time now. The official announcement was delayed while we worked on some technical issues. The first egg of the season may happen at any time now. Both eagles are strongly keyed in to the site and spend significant time on the nest, either feeding or arranging nesting material. This pair has a history of laying in late January/early February so we'll keep a sharp eye on the nest.




Some technical notes regarding the cam for this year.


1. There are fewer people available to manipulate the cam. We will work to ensure that we continue to provide great coverage of the nest, when no one is actively monitoring the cam it will be left in a position that provides the best coverage of events at that time. Keep in mind that this is one of the only cameras that actively follows the action in and around the nest. Doing so requires a great commitment of time.




2. The infrared (nightvision) has previously been controlled by an automated function that allowed it to be turned on/off on a schedule. Due to an apparent software hiccup this automated sequence is not functioning. We are still able to turn the infrared on/off manually and will make every effort to do so in a timely manner. Please be patient - the infrared needs to be turned on/off outside of normal working hours and there are times when a camera operator is simply not available.