Stearns Pond: Loon Necropsy

Stearns Pond Sweden, ME Found June 29, 2014

Stearns Pond
Sweden, ME
Found June 29, 2014

Loon necropsies provide us with a good way to assess threats to the loon population.. Through these necropsies, we learned that lead poisoning is the leading cause of death for our loons.  Each necropsy begins with an x- ray, followed by an internal exam of all the organs.  This loon was found this summer on Stearns pond in Sweden Maine.  Based on the initial x-ray, I thought this bird died from lead poisoning because I could see  fishing gear in his gizzard. However, none of this fishing gear ended up being lead.  With every necropsy, you start by examining the external features of the bird. We look for any external wounds, broken bones, dislocated joints, and external parasites. In the case of this bird, I found abrasions and bruising on his feet and around his left eye. He had no broken bones or dislocated joints and I found no external parasites.

Both his left and right feet were bruised. They both had abrasions as well.

Both his left and right feet had scrapes and bruises.

Next, we examine the internal anatomy for any abnormalities. These include any discoloration, lesions, pre-mortem clots, parasites, organ enlargement or atropy and foreign bodies. This loon was  in great body condition. He  had plenty of fat and  great muscle mass. One of the first abnormalities I noted was abdominal bruising on the lower part of his body. He also had a large pre-mortem clot on the underside of his sternum, as well as a lot of blood in his air sacs.

The lower part of his abdomen was bruised.

The lower part of his abdomen was bruised.

He had a large pre-mortem blood clot under his sternum on the left side of his body.

He had a large pre-mortem blood clot under his sternum on the left side of his body.

His organs, including his heart, lungs, liver and pancreas looked normal. The exception was his spleen, which was greatly enlarged. We confirmed  his sex as well. Female loons only have  a single ovary, whereas the males have two testes. Based on all the abnormalities found, we try and come up with cause of death. In this case, the bruising on his abdomen, combined with the large blood clot on his sternum and an enlarged spleen suggests blunt force trauma.  While it is  difficult to say exactly what caused his injuries,  he could have been hit by a boat or even crash landed somewhere.  If you find a dead or injured loon, please call our loon hotline:  (207)-781- 6180 ext. 275.  

What factors influence loon nesting success?

loon with eggIdeal loon nesting sites are located in less developed areas where human disturbance is minimal. They are often located near the water’s edge on the leeward side of islands or peninsulas. However, many factors influence loon nesting success. These include:

  • Fluctuating water levels caused either by dams or storms events can interfere with nesting success. High water levels can flood the nest, while low water levels make it more difficult for loons to slip on and off the nest undetected by predators.
  • Human activity can reduce nesting success, driving loons off their nests. During the summer, when loons are driven off nest, high temperatures can kill the eggs. Boat collisions can separate chicks from their parents, as well as cause chick and adult mortality. Additionally, there are more egg predation events in developed areas because raccoon, skunk and crow numbers are generally higher in these areas.
  • Predation is an important factor limiting nesting success. Raccoons, skunks, crows, minks, otters, birds of prey, snapping turtles and even large fish pose dangers for either eggs or chicks.
  • High insect numbers can drive loons off nest. In Wisconsin, 70% of loons nests were abandoned this year because of black flies
  • Loons with higher mercury levels have less nesting success. High mercury levels interfere with egg development and decrease the number of hatched eggs. Lead poisoning can also interfere with the ability of loons to take care of their chicks.



Moberg, G. Loons abandon their eggs due to black fly outbreak in Northern Wisconsin. WPR(2014).Accessed July27th 2014.From:

Radomski, P.J., Carlsom, K., & Woizeschke, K. Common Loon(Gavia immer) nesting habitat models for north-central Minnosota lakes. Journal of the Waterbird Society 37 (2014): 102-117.

Schoch, N., Glennon, M.J., Evers, D.C., Duron, M., Jackson, A.K., Driscoll, C.T., Ozard, J.W. & Sauer, A.K. The impact of mercury exposure on the Common Loon (Gavia immer) population in the Adirondack park, New York, USA. Journal of the Waterbird Society 37 (2014): 133-146.

Spilman, C.A., Schoch, N., Porter, W.F., * Glennon, M.J. The effects of lakeshore development on Common Loon (Gavia immer) productivity in the Adirondack park, New York, USA. Journal of the Waterbird Society 37 (2014): 94-101



Are painted lead jigs any safer for loons?

Starting in 2016, the sale of bare-lead headed jigs will be banned, followed by a ban on their use in 2017. However, the sale and use of painted lead jigs will remain legal. Does the paint protect loons from direct lead exposure? See what happens when a painted lead jig is placed in a rock tumbler. The conditions in the tumbler simulate the mechanical grinding inside a loon’s gizzard.

Brand New

Brand New

Day 1


five last

Day 5

Day 7

Day 7


Day 12

By day 12, the majority of the paint was eroded from the jig, making the painted lead jig no different and no less toxic from a bare headed lead jig.

Where to buy lead-free tackle in Maine

I’m working on compiling a list of tackle shops in Maine where people can buy lead- free tackle. If you know other shops selling lead-free tackle, email me at

  1. The Tackle Shop: (207)-773-3474, 61 India St, Portland, ME 04101
  2. Saco Bay Tackle Shop: (207)-284-4453, 977 Portland Rd, Saco, ME 04072
  3. Luke’s Reel Repair: (207)-985-2492, 737 Alewive Rd, Kennebunk, ME 04043
  4. Mainely Bait & Tackle: (207)-993-3031, 1340 N Palermo Rd, Palermo, ME 04354
  5. M.C.W. Bait & Tackle: (207)-642-3039, 60 Fort Hill Rd, Standish, Maine 04084
  6. Moosehead Bait and Tackle: (207)-534-226, Jackman Rd, Rockwood, ME 04478

My first night capturing and banding loons

Killingbeck_Beaver Cove#2

As soon as the sun went down, the capture began.  We set off Tuesday evening from Gorham, Maine and headed to Crystal Lake in Massachusetts. The banding team included a veterinarian, two field biologists and me. We took off from shore in a canoe. One person drove the boat. Another person searched for loons. I sat at the front of the boat, illuminating the lake with a spot light. At first all we saw were geese. Then suddenly we spotted a pair of loons with their two chicks. I kept the light focused on the loons as we moved the canoe towards them. To draw the loons closer to us, we played recorded loon calls. Next, the actual capture began, which, from my perspective, went down extraordinarily fast. In what felt like seconds, the loons were scooped up head first into the net and out of the water. Our first capture was the female loon followed later by the male loon with their two chicks.  With the loon wrapped in a towel, we headed back to shore to take measurements, band the bird and take blood samples. As I sat holding this loon, I learned some important things.  One, when holding a bird, always wear pants. Capturing and banding loons, while exciting, is not glamorous work. In addition to the thick clouds of bugs surrounding me, my legs were covered in a layer of bird poop by the end of the night.  My running shorts provided me with little protection. Thankfully, vet school has done wonders improving my tolerance for gross things. Two, loons are strong birds. It was more difficult than I had envisioned holding down both her legs and wings as everyone rushed to complete everything.  The night ended around four thirty in the morning when I rolled or rather collapsed into bed.  The loon family was safely returned to the water and reunited with each other. Overall, my first time helping capture and band loons was pretty amazing.   For future captures though, I’m wearing pants.

Fish Lead Free: Make a Difference!

Lead Tackle Exchange Kits: Get Free Tackle!
We are looking for organizations and individuals interested in hosting lead tackle exchanges. Exchanges can be a one-time event or an ongoing collection at your local library, municipality, marina, or office.
We supply a kit with all you need to get started: information about Maine’s lead-free sinker and jig law, lead-free sinkers and jigs to distribute to anglers and a collection container for old lead tackle. Kits will be ready to distribute by early June. Sign up now!

Loons & Lead Outreach Programs
Do you have an organization or civic group in need of a speaker? Would you like to learn what you can do to help Maine’s amazing Common Loon? We have an exciting and informative 45-minute multi-media presentation available. Filled with new video and award-winning photos, this interactive presentation will answer all the questions you’ve ever had about loons in Maine. You will also hear about the many varieties of lead-free tackle on the market and have the opportunity to take some to try for yourself. Call now to reserve!

Dead Loon Hotline: (207) 781-6180 x275
This summer, we are looking fo assistance recovering dead loons from Maine’s lakes and ponds. Over the last 30 years, we have recovered 500 dead loons. With the help of Tufts WildlifeClinic, we have documented that lead poisoning continues to be the leading cause of death for adult loons in Maine. We would like to increase our collection efforts this year. Please call the hotline if you see a sick, injured or dead loon, and we will collect and transport it to Tufts Wildlife Clinic.

For more information, contact:
Susan Gallo, Maine Audubon Wildlife Biologist
(207) 781-6180 x216