Canada Goslings

Last year I posted about a pair of Canada geese who nest on the small island in Crossroads Marsh. At that time the beavers were active and had raised the water level of the marsh, substantially reducing the size of the island. I wondered if the geese would be successful in raising a brood. Click here to see this post and for a general discussion of Canada goose nesting behavior. As far as I could tell, there was only one egg in the nest last year, but it eventually rolled off the nest to the water’s edge. As best I could tell, the geese abandoned the nest. This year they were back and built a new nest. Although the beavers have left the building and apparently moved upstream, the water level remains high. When I stopped by a week ago (April 27) I saw 2 eggs in the nest, but as you will see, there must have been 3 eggs. The mother was off the nest; apparently she finally got hungry. On Saturday, May 2, I was back bird watching. The nest was empty, but the geese were on the shore with their goslings. The picture above (courtesy of David Rosenthal) shows the family on Sunday, May 3. The two adults are guarding 3 goslings, one of which is smaller than the others. The remains of the down-filled nest are in the background.

It takes about 6-9 weeks for the goslings to mature to fledging. Both adults will guard the goslings vigorously until they are able to fly on their own. They will probably stay in this pond, or the flooded area beyond it, until the goslings mature. Interestingly, the adults undergo their spring molt at the same time that they are raising the goslings, and are unable to fly during this time. They usually regain flight ability around the same time as the goslings are able to fledge. This timing may be evolutionarily advantageous, since the adults do not abandon the flightless young, and therefore don’t need to fly during this period. In winter, the young geese will migrate with their parents and in spring will usually return to the same water where they were born. During the spring, a large number of geese are seen around Crossroads Marsh and nearby ponds around the Pennypack Trust property. I would be curious how many are the prior offspring of this pair, or are otherwise related to each other.

Canada geese are very adaptable to suburban environments. They eat grasses which are present in abundance. Although considered a nuisance in golf courses and open parks, they are natural natives of the local ecosystem. Although common, I always enjoy seeing them in their native habitat.

Thanks again to David Rosenthal for sharing his photos.

Gosling Update. I was out birdwatching this morning, May 7, with binoculars, but no camera. The two adults and two goslings are moving around the pond. The juveniles are already much larger only 4 days later! The third smaller gosling seen in the top picture must have died, since I didn’t see it anywhere. This is not unusual; it is rare for all the hatchlings of any species to survive the first year. The small one may have hatched later than the other two, or may have had some other physical problem. At least two other pairs of geese were on the pond, possibly their relatives. We may soon learn the carrying capacity of the pond.

Out again May 8, this time with camera. The two surviving goslings may be about a week old. They are starting to look more goose-like, and definitely bigger than last weekend.

And then there was one. Out on May 22. There is only one gosling left with the adults. The other must have been lost to disease or predation.

There are about 8 adult geese on the pond, and I noted at least 20 in a nearby field yesterday. There is no shortage of Canada geese. The high mortality rate among young birds may seem troubling, but without it the goose population would explode. If an adult pair lived several years and produced two viable offspring per year, the population could triple or quadruple within a few years. The “balance of nature” is not an easy process, but the alternative would ultimately be over population and either starvation or the inevitable imposition of population control by humans.