Aquatic Invasive Species and Montana's Loons

Montana's Aquatic Invasive Species (AIS) are plants or animals that are non-native to Montana ecosystems, meaning they do not have natural diseases or predators to keep them in check. If introduced, their populations explode damaging the ecosystem they have invaded, impacting Montana's economic, environmental and/or human health.

Anyone who works or plays in and around water can unknowingly transport AIS and once established, complete eradication is usually impossible or prohibitively expensive. While several AIS are already present in loon country, the ones we want to focus on are non-native zebra and quagga mussels.

Montana's Fish, Wildlife and Parks (FWP) have actively monitored for these mussels for over a decade, instigating "Clean, Drain, Dry." Up until 2016 none had been conclusively detected in Montana's waters.

In October 2016, a sample detected the presence of mussel larvae (called veligers) in the Tiber Reservoir. Then suspect samples from Canyon Ferry and the Missouri River south of Townsend were found. FWP deployed mussel sniffing dogs and state divers to search for adults mussels.

At this time, no adult mussels that reproduce have been found. In November 2016, the Montana Mussel Response Incident team formed, including FWP, Montana Dept. of Natural Resources and Conservation (DNRC) and the Governor's Council on Invasive Species to manage outbreaks.

The Montana Loon Society is interested in predicting how aquatic AIS like zebra and quagga mussels might affect Montana's loon population. Here are some areas for concern:

1) These mussels are filter-feeders which vary in size from the nail on your little finger to the nail on your thumb. They suck in water containing microscopic plants called phytoplankton and microscopic animals called zooplankton. Clear water is ejected after the plankton are removed. Phytoplankton, being plants, are the first level in the aquatic food chain. Zooplankton feed on phytoplankton. Tiny fish of different species consume both phytoplankton and zooplankton which are consumed by larger and larger fish.

Loons are primarily fish-eaters here in Montana so as mussels reduce the foundational populations of plankton, the food web above these organisms collapse. The fish populations that loons and their chicks depend on will be reduced over a relatively short time.

2) An estimated average concentration of mussels in Lake Michigan is 70,000 per square meter. Each mussel filters up to one liter of water per day causing the water to look very clean and causing people to think that the lake is in good shape. But clean water means there is little or no food for fish. Clear water allows sunlight to penetrate into deeper waters stimulating the growth of unwanted plants (weeds) - including various species of alga which actually poison the waters of shallow ponds and bays during late summer months.

3) The National Oceanic and Atmospheric Administration has estimated that there are four quadrillion zebra and quagga mussels at the bottom of Lake Superior. The filter-feeding activity of these organisms means that there is less food and energy in the upper levels of lakes which is where most aquatic organisms, including loons, feed. Essentially, these mussels have turned the lake "upside down" by concentrating the reduced food supply at the bottom of the lake.

Furthermore, mussel feces rich in organic matter, settles on the bottom where it is fed upon by snails, invertebrates and bottom-feeding fish. Scientists are trying to determine if lake bottoms rich in mussels and their feces could be creating the conditions that are producing increasing outbreaks of avian botulism which have been causing massive bird fatalities in the past few years. If the avian botulism bacterium is in the water, it will be strained out by the mussel as it feeds. This means that consuming a mussel or something that ate the mussel could be the cause of avian botulism.

"Aquatic invasives like zebra or quagga mussels can be prolific and cause trophic collapse in aquatic food chains causing real impacts to common loons that depend on Montana's lakes for forage. Our loon ranger program helps provide public education at boat ramps on AIS aimed at helping folks detect AIS, prevent their spread, and understand the impacts AIS can have," said Mark Ruby, Forest Service Wildlife Biologist, Swan Lake Ranger District and MLS Board Member.

Bottom line, we must consider the considerable impacts that zebra mussels could have on loons in light of the fact that this AIS was found in central Montana. The next question is what can we do in the meantime? We must:

1) Support all efforts to stop and search ALL boats from kayaks to cruisers.

2) Get trained and volunteer to help at an inspection station near you.

3) Always clean, drain and dry our own boats.

4) Never move water in any container from one lake to another.

5) Not lose hope! Our loons are counting on us.

Blackfoot/Clearwater (Ovando/Seeley Lake) Loon Report

Data collected by Loon Ranger Keely Benson

The Clearwater area had five nest attempts. Three were successful with a total of six chicks hatched, 2 each on Placid, Clearwater and Summit that survived until July Loon Day. Seeley Lake nested, but did not have chicks. Rainy nested and had one chick that did not survive. Alva had no confirmed nest. Signs were set on five lakes: Clearwater, Rainy, Alva, Seeley and Placid.

In the Blackfoot watershed, Upsata nested, lost the first nest and renested. One chick hatched, but only survived six days. Signs had been placed around the nest. A bald eagle nests in the area, but unknown if the eagles captured the chick. No nests were found on Doney or Shoup.

This combined area had six chicks that survived until the July Loon Count Day.

2016 Clearwater/Blackfoot Loon Chick Count at a Glance:

To quickly see how our Blackfoot and Clearwater loon neighbors faired last year, take a look at the included chart. Bumps and dips naturally occur in loon numbers.

In Montana, flood years are a major cause in the drop in chicks, but not all areas flood the same year. So, during some years, such as 2006, the Clearwater had a good year while the Blackfoot didn't fare well. Conversely, in 2010 and 2011, the Blackfoot did better than the Clearwater. It is only cause for concern if numbers drop and drop without bounce-back. However, during these same years the number of chicks in the state of Montana has remained roughly the same with an average 41 chicks per year, which is considered a viable loon population. In 2016, 55 total chicks survived in the state until the July Loon Day count and are assumed to have migrated in autumn.

Swan Lake Ranger District

Data collected by Alissa Anderson, USFS Wildlife Technician

 During the 2016 loon nesting season six chicks survived on four lakes; Loon Lake (Ferndale) - one chick, Loon Lake (Kraft Crk.) - two chicks, Pierce Lake – one chick and Van Lake – two chicks. This is the first year that Van Lake is known to have successfully produced young. A seventh chick was lost at Loon Lake (Ferndale) between 22 and 28 June for unknown reasons although resident bald eagles regularly forage on that lake from a nearby nest.

Non-breeding and/or non-successful pairs were observed on seven other lakes: Crystal, Glacier, Holland, Horseshoe, Lindbergh, Swan and Upper Holland Lakes. The loon reported on Holland and Horseshoe Lakes may actually be the pairs nesting on near-by Pierce and Loon (Ferndale) Lakes.

Of the 19 lakes surveyed in the monitoring area, 23 adults were observed. Only five lakes did not have any loons recorded on them.

A loon platform on Pierce Lake, refurbished in 2015, was used again successfully in 2016. A new (floating island) platform was installed on Lindbergh Lake, in the fall to enhance habitat at the head of that lake for the 2017 season. Increased monitoring efforts at Crystal, Glacier, Holland and Lindbergh Lakes are desired for 2017. Total 2016 chick count was six chicks on four lakes.