Note on the Mission Eagle Nest Canada Goose Behavior
Thursday, May 02 2013 @ 06:44 PM EDT
Contributed by: davidh
I have raised a lot of geese over the years, including having one of my wild pairs hatch eggs today (what reminded me to make this note!) and our Mission geese seem to have adopted a great strategy that I have not seen before.
The first comments by an observer seeing a Canada goose in the nest drew comments that "someone had Photoshopped" the image to show a goose in the eagle nest. That shortly was disproved. The goose was back and by April 11 two eggs were clearly seen in the nest. By April 15 4 eggs were buried in the nest cup and covered up each time the goose left. That afternoon, while the geese were out of the nest, one of the adult eagles with the band on the right leg was seen on the nest but "she" (?) did not disturb the goose down or the hidden eggs. Around 6:00 PM that night the geese returned and the 5th egg was laid. The great joy was that the eagle nest that Percy and Debbie worked so hard with our group to install the cams on was at least going to produce something -- a close-up opportunity for a lot of us to watch these magnificent geese, whom they have named "Bonnie and Clyde" since they stole the eagles' nest.
Then the concern became, would the eagle pair allow the geese to nest in the now unused eagle nest? Time would tell. Only about an hour after the 5th egg was laid one of the eagles tried to fly into the nest while the geese were there. "Clyde", otherwise known as "Father Goose", flew out of the nest to chase off the eagle.
During the next few days it was observed that the geese had an eagle strategy. The goose stayed at least part of the night on 7 eggs as of the 19th of April and she then stayed incubating the entire night from then onward as of the 20th of April. So the eggs should hatch 25 - 28 days from the 20th. (This unfortunately makes it a long experience of expectation for the ground observers who want to capture the chicks jumping from the nest on their cameras.) It's likely we'll see the first couple of hours in the morning with a head poking up. This will be a clue to be there later in the day as it warms up. The goslings have to sit under mom most of the night before they dry off. Most of my Canada geese hatch out on the 28th day so I predict the hatch on the night of May 18th or early the 19th. This probably means the goslings will jump to the ground either the afternoon of May 19 or midday on the 20th. Interestingly, she apparently laid an 8th egg on April 20 -- a full house. In fact this number is on the high side of averages. Since she could bring the brood off a day or two earlier our ground observers, who wish to photograph the 'jump' for everybody, have an increased vigil!! To cover errors you should be watching around the 16th or 17th. To add to the confusion, since the female, "Bonnie", started incubating on the 19th, though not full time, the first 7 eggs could hatch a day prior to the 8th egg. The hen will wait until all have hatched before she leads them from the nest and down to the water.
Comment on a dump nest: Geese and waterfowl generally frequently have "dump nests". This is where two or more females will lay in the same nest, increasing the number of eggs over the regular clutch size. This is probably not the situation here but now that genetics can be tracked, the dump nest concept is more commonly being recognized.
Back to the defensive behavior of our geese. After our observers witness the adult eagle on the nest on April 15, it is likely the geese made the same observation. In all likelihood, the nearby feeding or loafing parent goose saw the eagles land on the nest as well. In fact it is fair to assume they have seen the eagles in this precise nest over the past years and currently nesting across the highway -- geese are not unobservant! Then after a few more goose eggs were laid we witnessed the female goose actually incubating the eggs with the male standing on-guard right up in the tree beside the nest. He was going to be on hand if the eagle returned.
Then, as if on cue, as one of the eagles approached the goose nest, the male goose flew up at the eagle to drive it away from his hen. Very defensive and effective! In all my years of watching wild geese or raising wild geese on my ponds usually the male goose stands guard about 75 to 200 feet away - never on the edge of the nest. In discussions with various goose biologists it always seemed logical that the male, while protectively on duty and nearby, did not wish to attract too close attention to his nesting partner and their valuable eggs. This Mission gander, who spends a lot of time standing on the actual nest rim seems to be balancing off attracting attention to the nest but doing so since he seems to sense the need to be very close to offer protection against the eagles. Maybe this tradeoff is more common than I realized -- particularly a good adaptation when nesting around busy eagle territories.
Actually seeing Canada geese nest in unoccupied or alternative eagle nests is not uncommon and I usually see a local eagle nest each year supporting a goose clutch. I have yet to be there when the goslings have to make the 100 foot plus drop to the ground. Of course, like the whole range of tree nesting ducks, the tiny newly hatched young have very little mass so are in little danger of hurting themselves when they hit the ground.
As I write this at 10:30 AM my male goose is back on the pond (probably 100 feet from mom who is sitting on the nest on the barn roof) and I expect him to return to standing on the second barn, giving him his regular overlook position, before mom is ready to jump down and encourage the goslings off the roof. Neither of his lookout positions from the barn roof or the pond offer him a direct view of the nest but the male is always on the alert for passing ravens, crows and eagles. This morning when an eagle flew over, easily 300 feet high and not likely an immediate threat, the gander flattened out on the roof ridge -- well tried too! He was still very obvious on the tin roof! A few minutes ago with the gander on the pond another eagle flew over and he flattened off across the surface of the pond -- trying to be an inconspicuous silhouette.
When the female goose did not appear for her 7:30 AM morning feed today I thought the time was getting close. I climbed the barn roof ladder and sure enough there was a section of egg beside her -- hopefully the hatch was complete during the night. If so she will probably entice the chicks down during the warmth of the day and in the meantime they will all be drying out and absorbing the last of their egg yolk -- the food source that has driven their development. If they did not all hatch out last night or early today then she will probably sit with them overnight and bring them off in the morning.
I expect a pair or two of wood ducks to hatch this week as well -- summer is nearly here.
P.S. Thanks, Karen, for pulling the dates of these events off the Forum.
To follow the discussion forum for the Mission, BC bald eagle nest with the geese click here:
To watch the Mission eagle cam click here: