Squam Lake Loon Initiative
Between the fall of 2004 and the spring of 2005, Squam Lake lost seven of its loon pairs. The decline from 16 to 9 pairs represented 44% of Squam's loon population, a drop unprecedented on Squam or any other large lake in more than 40 years of LPC's history of monitoring loons throughout New Hampshire. It also brought Squam's loon population to its lowest level since LPC began to survey Squam Lake in 1975.
Click here to watch the Squam Lake Loon Initiative Video.
Created in 2007, the Squam Lake Loon Initiative (SLLI) includes an increased monitoring, research, management and outreach effort to: 1. Determine the overall survival and reproductive success of Squam’s remaining loon population; 2. Assess causes of nest failure and collect inviable eggs from failed nests for analysis of a wide range of contaminants and pathogens; 3. Rescue sick or injured loons to increase loon survival whenever possible; 4. Find and collect loon carcasses, determine causes of death, and test liver samples from dead loons for contaminants and pathogens; 5. Band loons to allow us to identify and track individual birds and collect blood and feather samples for analysis; 6. Determine survival and breeding success of previously banded and sampled loons, and relate survival and breeding success of individuals to their levels of contaminants and pathogens; 7. Incorporate results into a systems dynamics or other explanatory model to determine the relative contributions of a wide range of possible stressors on the mortality and reproductive failure of loons on Squam Lake; and 8. Restore and maintain a healthy and stable population of loons on Squam Lake as a component of a healthy statewide population of loons.
Like loons throughout New Hampshire, Squam Lake’s loons face multiple stressors, including mortality from lead fishing tackle, mortality and disturbance from human recreational use of the lakes, and the effects of increasingly extreme temperatures and precipitation, habitat loss, and pollutants. However, unhatched loon eggs collected by LPC (under state and federal permits) from Squam between 2005 and 2007 revealed high levels of a number of contaminants, including PBDE (flame retardants), PFOS (stain guards), PCB (industrial insulating/cooling agents), and chlordane (a pesticide). Levels of contaminants from Squam eggs during 2005-2007 were two to nine times higher than levels found in eggs collected from the other lakes. Our knowledge of the effects on loons of these contaminants, and especially combinations of contaminants, is limited. However, some of these contaminants were present in loon eggs at levels that have been shown to affect the physiology, health and/or reproductive success of other bird species.
Squam’s loon population has also experienced extremely high levels of mortality from lead fishing tackle. Since the opening of the reconstructed public boat launch in 2001, the rate of mortality from lead fishing tackle on Squam Lake has doubled (Figure 1) and is twice the overall statewide rate of lead mortality during the same period. From 2001-2012, Squam has lost on average 1.9% of its adult loon population annually due to lead fishing tackle. Although it is not possible to demonstrate causation, it is worth noting that, since 2001, the number of boats counted during an annual boat census of Squam, the number of fishing tournaments, and the number of boats participating in fishing tournaments has increased at a statistically significant level.
Frequently-asked Questions About the Decline of Squam's Loons
Could these contaminants be coming from the ocean, rather than from Squam? LPC’s data indicates that ocean contaminants and pathogens, while present, are unlikely to be the driving force behind the decline of loons on Squam. Data from banding done by LPC and the Biodiversity Research Institute in Gorham, Maine, indicates that Squam’s loons do not migrate or overwinter as a group. Loons breeding on Squam probably overwinter over a large stretch of the Atlantic, from Maine to Rhode Island. Therefore, any contaminants or pathogens picked up on the ocean would affect loons on many lakes and not be specifically focused on Squam as these declines seem to be. Research also indicates that the materials in eggs primarily come from recent (within three week) dietary sources, an additional fact pointing to Squam as the source of contaminants in loon eggs. Stable isotope testing conducted by LPC on these eggs indicated that, while there may be some mix of freshwater and ocean sources supplying nutrients to the egg, the majority of the material deposited in the egg comes from freshwater sources.
Could Squam’s loons simply be migrating to nearby lakes rather than expiring? LPC’s research and monitoring indicate that emigration of loons cannot explain the drop in Squam’s loon population. We know from tracking the movements of banded loons that few loons disperse farther than 10 miles after they have lost a territory. LPC has not recorded an increase in the loon population of neighboring lakes, and banded loons that have disappeared from Squam have not been sighted on other lakes. These findings suggest that the territories vacated on Squam during the decline are a result of mortality, rather than emigration of loons.
Could the Squam eagles be contributing to the decline? Like recreational use of Squam, eagles are more likely to contribute to reduced productivity of loons than to mortality of adult loons. There have been a few cases of eagles predating adult loons in the Midwest, but these loons are only half to two-thirds the size of our large New England loons. Eagles established themselves on Squam in 2002 and first bred successfully in 2003, and Squam loons fledged 26 chicks over those two years. It is possible that Squam’s eagles might have developed a taste for loon chicks over the past several years, but LPC has not heard of any eye-witness accounts of eagles predating loon eggs, chicks or adults on Squam.
Could density dependence (i.e., too many loons) on Squam have contributed to the decline?
Data collected by LPC since 1975 does not indicate that density dependence is a factor on Squam Lake. Although loon chicks have been killed on Squam by intruding loons, there is no clear relationship between the number of loons recorded on the lake and the rate of chick survival on Squam. If density dependence was impacting adult loons, we would expect to find carcasses of adults killed by other loons. Since 2004, only one adult loon has been collected on Squam that was killed by another loon.
In 2014, Squam had twelve pairs of loons, which hatched four chicks and three survived. The reproductive success of Squam’s loon pairs remains far below pre-2005 levels, and relative productivity rates have remained low since the period of critical decline in 2005-2007. Loon breeding success from 2008-2014 is less than half the statewide average and far less than the rate needed to maintain a viable population (0.48 chicks surviving per territorial pair).
Squam gained one pair of loons in 2015, with a total of thirteen pairs of loons on the lake. The rate of nesting was very good this year, with ten of the thirteen pairs nesting. To date, two pairs have overincubated (i.e., gone beyond the expected hatch date and the eggs will not hatch), two pairs have had one of the pair members evicted from the territory during incubation and the nests were abandoned, one nest was washed out by a storm, and one nest was abandoned after a combination of human and loon disturbance. Three pairs have hatched six chicks and four survive.
LPC's research into the contaminants found in Squam's loon eggs suggests that a point source of contamination in the northeastern sector of the lake may be the source of the PBDE's (flame retardants) and PFOS (stain guards), while legacy contaminants, such as DDT, chlordane, and PCB's, may have come from a diffuse source. LPC is continuing to investigate sources of contaminants and the multiple factors that contributed to the declines in survival and productivity since 2005.
The Squam Lake Loon Initiative has already provided critical baseline data on contaminants and other environmental stressors on loons which will be invaluable to assess changes in, and effects of, these stressors in the future. The collaboration of researchers formed as a result of the decline of loons on Squam Lake is unprecedented, and the testing being done on loon samples is the most comprehensive undertaken anywhere to date. We anticipate that this initiative will help avoid future declines of loons on Squam and on other lakes; bring to light what could be a much larger, more systemic problem on Squam indicated by the decline of loons; inform other LPC initiatives such as the LPC Loon Recovery Plan; and help LPC and others make more informed decisions to protect Squam’s loons, other wildlife, and the ecological integrity of Squam Lake, as well as lakes throughout New Hampshire. Squam Lake will continue to play a leading role in advancing our understanding of loons and their challenges in New Hampshire even as LPC works to recover a healthy population of loons on Squam Lake.
Objectives for the Squam Lake Loon Initiative in 2015-2016 include:
- Testing recently collected loon eggs from failed nests to monitor current contaminant trends
- Testing archived loon egg samples to measure historical contaminant levels
- Testing eggshell thickness for eggs with known contaminant levels to determine the effect of contaminants on eggshell thinning and nest failures
- Banding loons on Squam Lake to measure adult survival, productivity, and contaminant levels of known individuals
- Analyzing data from nest cameras and temperature loggers to investigate disturbances at nests and the influence of climate on incubating loons
- Testing loon blood samples to identify pathogens and other health concerns
- Analyzing data on impacts of recreational activity on Squam Lake’s loons
- Collecting and testing sediment samples from the tributaries identified as possible point sources for contaminants to zero in on possible sources
- Continuing intensive monitoring, management, and outreach to support Squam’s loons