We will resume actively oiling goose eggs on the three big islands of Lake Truesdale in the upcoming weeks of spring 2024.

We do this to control the population of Resident Canada Geese on the lake.

We will do an initial census of the three* main islands of the lake to determine the number of nests and the egg quantities. (*also the small private island in north end cove of lake — and any inaccessible shoreline areas that might house a stealthy pair of geese and a nest)

Last year (2023) we found ten different nests between the three islands and continued to monitor the islands through the spring. We acted as needed since new nesting pairs continued to show up throughout the spring season with newer waves of paired geese landing weekly to scope out the neighborhood.

Egg oiling requires a permit from the Fish & Wildlife Service (FWS) which we have obtained. Truesdale Estates Association has renewed its FWS RCGR (Resident Canada Goose Registration) permit #13757A and currently there are seven lake residents who are named on the permit and can serve as volunteers.

If you are interested in learning about this program — and adding your name to the list of federally approved volunteers — see below for contact info.

This is a FREE program for our lake. The only cost is the time given by the volunteers and the cost of the corn oil used for oiling.

The program on Truesdale Lake started in 2008 and has been very successful in controlling the population of resident Canadian Geese on the lake. The number of geese was in the hundreds in the early and mid-2000s and the oiling program has been successful in reducing these resident geese to close to zero recently. (We do get transitory geese all throughout the summer, but since they are not nesting they do not stay very long.)

As an example of what happens when we miss a nesting season: In 2019 the program did not have anyone oiling the eggs in time and the resident geese population shot back up into the 70-80 range — and possibly more. In 2020 we resumed the FWS program and there was only one resident family of Canada Geese on the lake for the summer. In the subsequent years 2021, 2022, and 2023 we have had at most one family of Canada Geese.

If you are interested in helping out, please contact us via email at lake@truesdalelake.com or via our Contact Form. The process is not too difficult and training is easy. We need to add your name to our FWS permit before you can be involved with the oiling program. There is no cost to join the program.

What is egg oiling?

Egg oiling is a long-term strategy that reduces the number of resident Canada Geese on Truesdale and other lakes through 1.) physical intervention and 2.) behavior changes.

Physical Intervention

The physical intervention is the actual oiling of the eggs after mating has occurred but before the eggs have developed embryos. In our lake this typically takes place in late March or early April and can be pinpointed by observing the mating ritual of the local geese couples and finding their island nests about a week later.

Oiling works best with a crew of two or three working together. One person finds the nests, one person keeps the geese away from the nest, and one person oils the eggs. It is possible to do this with one person if they bring along two umbrellas to shield the activity over the nests.

Oiled eggs are marked with sharpies to keep track of which ones have been treated. Records are kept for the number and location of the nests and the number of eggs in each nest as a requirement of permission from the Fish & Wildlife Service.

Behavior Change

The behavior change for the geese is the most important long term consequence of oiling the eggs.

We oil the eggs rather than simply break them because if the eggs are broken the goose simply lays more eggs. However, if the eggs are oiled, the development of the egg is stopped by preventing oxygen flow into the egg. This prevents the egg from hatching.

Since the geese do not know this, they sit on the eggs for the 5-6 weeks it takes for hatching. When the oiled eggs do not hatch, the geese view it as a “failed nesting.”

Resident Geese BAD — Migratory Geese GOOD

After a successful nesting which results in hatched eggs, the adult geese shed their flight feathers and take up residence with their new goslings on the lake for the entire summer and fall. We cannot chase them away.

This is NOT the outcome we want.

It is important to get all of the eggs and all nests oiled – or as many that are found. If there are enough goslings in a flock, even other members of the flock who may have had failed nestings will stick around and lose their flight feathers to support the new parents in the flock as “aunts” and “uncles.” This creates a large resident flock for the entire summer.

In a failed nesting with no goslings hatched, the adults keep their flight feathers, take off, and head further north for the summer. They do not have the time to lay more eggs and have the goslings fledge and fly before the end of the season. They are bachelors and bachelorettes.

This is the outcome we want.

These geese who fly away after a failed nesting also do not develop a preference for returning to Lake Truesdale next summer. They resume being Migratory Canada Geese (good) rather than Resident Canada Geese (bad).

Keeping the geese migratory means the problem is reduced both in the current year and in subsequent years.

Other geese will find and take up residence on Truesdale if we stop oiling the eggs, so we must keep up the program to head off more future residents.

We will also always have transient migratory geese — you can tell these geese since they are willing and able to fly away and visit other lakes since they do not have goslings to protect. They are not a long-term problem but they can be a nuisance periodically, especially on the beaches.

Oiling Results

In 2021, the crew of egg oilers has oiled over 100 eggs between the three islands. This prevented the hatching of those eggs and has interrupted the resident behavior of those goose parents. The aim was to not have them return for the next year — and the resident geese numbers were way down from 2021 to 2023 numbering only 5-8 goslings down from over a hundred when the program was not undertaken.

To be successful, there has to be an initial oiling treatment and several follow up oiling treatments. Timing is the key to successful outcomes. In past years, new couples appeared and new nests were created after our first and second trips to the islands. Each island ultimately required 4-5 trips. Nesting season was done by early May (no new nests, no new eggs observed).

Summary: Egg oiling has made a huge difference in controlling the resident goose population on Lake Truesdale.

Anecdote: When we first moved here in 1999, we would arrive home to 60-80 geese/goslings on our lawn. There was easily double or triple that number on the lake. Lawns were covered in goose droppings. The beaches were favorite spots for goose gatherings. I have photos (deep in the archive) that I can dig up in case you think I am egg-agerating.

We have gotten it much more under control relative to those days — but we can always do better. Will you step up to help? We can always use more volunteers! Thanks everyone for your help and support.

Resources:

Permit requirements: https://epermits.fws.gov/eRCGR/geCOND.aspx