Egg Oiling Update #2

May 24, 2020 by rob

This is Update #2 for our 2020 egg oiling. To read the first update, click here. To read the initial posting about Truesdale egg oiling, click here.

Background

For Spring 2020 Truesdale Lake applied for and received a United States Fish and Wildlife Services permit for egg oiling. The permit number is FWS RCGR #13757A. More information about Canada Goose breeding control via egg oiling visit this link.

Status

There are three islands on the lake. From the north to the south they are: Waxwing Island, Ant Island, and Pirate Island. These are shown on the chart below.

Geese tend to nest on the islands because of the protection afforded from predators such as raccoons, foxes, coyotes, mink, and predatory birds.

Note: scale is for lake dimensions. Island dimensions are shown larger here than their true size.

Pirate Island Nests – Third Visit

On April 12, a return survey (third visit this season) of Pirate Island was done and found four goose nests (N1, N2, N3, N8) on the island. This is the same number seen during visit 2.

N1 southeast part of island. 10 eggs.
N2 southwest part of island. 3 eggs.
N3 northwest part of island. 6 eggs.
N8 north-center part of island. 6 eggs.

4/12 – Total eggs oiled on Pirate Island – 25 (24 intact).

Pirate Island Nest N1 – 10 eggs – April 12, 2020

Ant Island Nests – Second Visit

This reporting period resulted in many new nests on Ant Island. 21 total eggs in six nests.

N5 north tip of island with 5 eggs.
N10 (New) – SW on Ant Island with 6 eggs
N11 (New) – south center on Ant Island with 2 eggs
N12 (New) – south point on Ant Island with 3 eggs
N13 (New) – SE end of Ant Island with 4 eggs
N14 (New) – west side of Ant Island with 1 egg

Waxwing Island Nests – Third Visit

Found one new nest with three eggs on Waxwing Island. Total count is 4 nests and 22 eggs.

N4 – northwest end of island, 6 eggs.
N6 – southeast end of island, 6 eggs.
N7 – center of island, 7 eggs.
N9 (New) – center north of Waxwing Island with 3 eggs.

4/14 – Ant Island and Waxwing Island 43 total eggs in 10 nests.

April 24 Report

This reporting period combined two weeks and resulted in many changes as failed nests start to become evident and unhatched eggs from the abandoned nests are eaten.

Ant Island now has six fewer goose eggs from an abandoned nest, and nine more goose eggs for a total of 25 goose eggs.

There is a new Swan nest of eight eggs at the southwest end and a new Mallard Duck nest of nine eggs at the middle west side of the island – which were both left undisturbed.

Waxwing Island has three abandoned nests and sixteen fewer eggs for a total of only 6 goose eggs.

The Swan nest of eight eggs is still attended and was left undisturbed. Cygnets should be emerging very soon.

Here are the current nest designations and inventory for Ant and Waxwing Islands:

N4 – west tip of Waxwing Island with 2 eggs – abandoned
N6 – east tip of Waxwing Island with 0 eggs – abandoned
N7 – center west on Waxwing Island with 2 eggs – still attended
N9 – center north on Waxwing Island with 2 eggs – abandoned

N5 – north tip of Ant Island with 0 eggs – abandoned
N10 – SW on Ant Island with 8 eggs – attended
N11 – south center on Ant Island with 3 eggs – cold, unattended
N12 – south point on Ant Island with 5 eggs – attended
N13 – SE end of Ant Island with 6 eggs – attended
N14 – east side of Ant Island with 3 eggs – cold, unattended

Pirate Island nest – N9 – April 25, 2020

April 25 Pirate Island

Several nests were unattended and N3 had only one goose attending it. New nest N15 was noted in the northeast part of the island with six eggs. Total egg count 30 eggs.

N1 southeast part of island. 8 eggs.
N2 southwest part of island. 8 eggs.
N3 northwest part of island. 2 eggs.
N8 north-center part of island. 6 eggs.
N15 (New) northeast part of island. 6 eggs.

Final nest status – May 15

This is the briefest of reports since all of the fifteen goose nests found on the three islands have failed, with the exception of N1 (southeast and six eggs) attended on Pirate Island and N13 (east side and two eggs) attended on Ant Island, depicted in this photo.

All remaining eggs have been either addled or re-oiled. So far, we have spotted only one family with several goslings.

In contrast, last year, where egg oiling did not take place, at least ten Canada Geese families were spotted and goslings were too numerous to count. In addition since so many goslings were hatched, many geese with failed nestings also stayed to assist the flock in raising the broods.

The two male Mute Swans based on Waxing Island and Ant Island have been aggressively chasing geese away from their respective territory.

Summary of Egg Oiling in Spring 2020

At their egg population peaks, the islands had the following total eggs:

Pirate Island (south island) – 30 eggs counted at peak on April 25
Ant Island (middle island)- 25 eggs counted at peak on April 24
Waxwing Island (north island) – 22 eggs counted at peak on April 14

Total of all eggs at peak times: 77 eggs in 15 nests.

Combining the eggs and the parent couples from the 15 nests we believe we prevented a population of 107 geese and goslings (30 parents and 77 goslings) from summering exclusively on Truesdale Lake.

In addition, flocks of geese families summering on our lake would attract transient geese from their failed nestings to land and take up residence on Truesdale Lake, potentially adding even more Canada Geese to our summer resident population.

Hosting over 100 geese over the summer is something we absolutely want to avoid — and the efforts of our volunteers have met with success. If you are interested in helping next spring, please email lake@truesdalelake.com to get on our roster of volunteers.

We do have at least one pair of geese with goslings who slipped through our springtime search. We assume they were nesting on an isolated shoreline and not on the islands. We will also have unavoidable visits from transient Canada Geese throughout the season, but you will note the lack of goslings with these flying visitors. Since they don’t fledge their young on our lake, the possibility of them returning to raise a family here next year is reduced greatly.

This marks the close of the successful 2020 egg oiling campaign on Truesdale Lake! Thank you to Jill, Scot, and Rob for keeping on top of visits to the islands — and keeping track of the status of the nests and eggs for our end of the year required report to the US Fish and Wildlife Service.