Mergansers are a group of fish-eating diving ducks in the genus Mergus. There are three main species: the Common Merganser, the Red-breasted Merganser, and the Hooded Merganser. Mergansers are found across North America, Europe, and Asia. They nest in cavities in trees, rock crevices, and even nest boxes provided for them along rivers, lakes, and ponds. But do mergansers actually use nest boxes? Let’s take a look at the evidence.
Do any species of mergansers use nest boxes?
Yes, some species of mergansers do nest in boxes. The most common species found using nest boxes is the Hooded Merganser. The Hooded Merganser is the smallest North American merganser and relies heavily on cavities for nesting. They readily accept man-made nest boxes, especially in areas where natural cavities are scarce. Numerous nest box programs have had success attracting and raising the reproductive rates of Hooded Mergansers by providing suitable artificial nesting sites.
The Common Merganser and Red-breasted Merganser also occasionally use nest boxes, although not to the extent of the Hooded Merganser. These two species nest more often on the ground, in rock crevices, or in natural tree cavities when available. But they have been known to nest in boxes from time to time.
So in summary, yes, mergansers do nest in boxes, although the frequency depends on the species and availability of natural nesting habitat.
Why are nest boxes useful for mergansers?
There are several reasons why nest boxes are valuable conservation tools for mergansers:
1. Provide nesting habitat – Mergansers rely on cavities for nesting and suitable natural sites are declining. Nest boxes provide essential artificial cavities for breeding.
2. Protect from predators – Nest boxes can be placed over or near water, reducing the risks from terrestrial predators. The cavities also provide shelter.
3. Manage habitat – Nest boxes allow breeding habitat to be managed and maintained for mergansers in desired locations.
4. Monitor populations – Nest boxes facilitate monitoring and banding of merganser ducklings to track populations.
5. Increase reproduction – Nest boxes support larger merganser broods by providing favorable nesting conditions. More ducklings survive to fledge.
In short, nest boxes help increase merganser reproductive rates and allow closer management of their populations, especially the Hooded Merganser. The availability of suitable and safe nesting sites is likely a limiting factor for cavity-nesting mergansers.
History of Merganser Nest Box Programs
When did conservation groups start providing nest boxes for mergansers?
The earliest concerted efforts to provide artificial nest boxes specifically for mergansers began in the 1960s and 1970s.
For example, in a 1973 study published in The Journal of Wildlife Management, researchers in Minnesota set out nest boxes to attract Common Goldeneyes and Hooded Mergansers as part of an assessment of cavity-nesting waterfowl populations and reproduction on the Chippewa National Forest. This represented one of the first scientific efforts to utilize boxes for merganser conservation and research.
Around the same time, groups such as ducks unlimited initiated projects focused on installing nest boxes along important merganser breeding habitats, including rivers, lakes, reservoirs, and wetlands. State wildlife agencies also began participating in nest box programs aimed at mergansers and other cavity-nesting ducks.
These pioneering nest box efforts paved the way for the extensive merganser box programs still carried out across North America today. The designs, placement methods, monitoring techniques, and overall understanding of merganser box potential were established in those early conservation initiatives five decades ago.
Where were the first nest box programs for mergansers implemented?
The first dedicated merganser nest box initiatives were concentrated in the Upper Midwestern United States and in areas of eastern Canada. This region contained significant populations of mergansers along with threats to natural nesting cavities.
Specific early nest box sites important for merganser conservation included:
– Chippewa National Forest in Minnesota – One of the earliest merganser box research sites dating back to the early 1970s. Findings here helped improve nest box design and placement for mergansers.
– Lake St. Clair and Detroit River in Michigan – Merganser box programs by Ducks Unlimited helped restore nesting populations of mergansers after declines in natural habitat.
– St. Lawrence River in Quebec – Merganser box initiatives were implemented in the estuary in the 1970s to provide protected nesting sites.
– Wood Duck Valley in Manitoba – Conservation groups installed merganser boxes here alongside efforts for other cavity-nesting waterfowl species.
So the Upper Midwest, Great Lakes region, and southern Canadian provinces were pioneers in using nest boxes specifically for conservation of mergansers starting in the 1960s and 1970s. The positive results helped expand the practice across North America.
Merganser Nest Box Design and Placement
What are the best designs and dimensions for merganser nest boxes?
Here are some key design recommendations for merganser nest boxes:
– Box size – At least 12″ x 12″ floor dimensions or larger to accommodate merganser clutch sizes.
– Depth – 12-24 inches deep from bottom to entrance hole.
– Entrance hole – Oval shaped and at least 4″ high x 3″ wide. Located near top of front panel.
– Construction – Durable wood, metal, or composite materials. With adequate insulation and drainage.
– Predator guards – Metal flashing or guards around entrance hole to prevent predators from enlarging.
– Hinged roof – Allows easy annual cleaning and maintenance.
Larger dimensions, insulation, predator deterrents, and easy access for cleaning help create optimal, safe nesting conditions for mergansers raising their broods. Hooded Mergansers may utilize boxes as small as 10″ x 10″ x 16″ but larger is preferred.
Where should nest boxes for mergansers be located?
Here are some key tips for proper placement of merganser nest boxes:
– Over water – Install 3-4 feet above water on poles or structures. Reduces predation.
– Near foraging areas – Place boxes within a few hundred feet of good fishing habitat.
– Avoid disturbance – Choose secluded stretches away from heavy boat traffic or human activity.
– Face opening downstream – Allows ducklings to exit box safely towards water.
– Consider flooding – Position high enough to avoid rising water levels.
Proper placement above or near high-quality feeding areas allows female mergansers easy access to the box for nesting and reduces risks to eggs and ducklings. Following these best practices improves merganser acceptance and productivity.
Monitoring and Maintaining Merganser Nest Boxes
How are merganser nest boxes monitored?
Here are some standard techniques for monitoring merganser nest boxes:
– Annual checks – Inspect interior in late winter before breeding season for repairs. Install predator guards if needed.
– Observation – Watch boxes for signs of merganser activity during breeding season such as defending adults.
– Careful opening – Quickly open box to count eggs/young. Done by trained personnel wearing gloves.
– Record contents – Note number of eggs, young, age, bands if present. Photograph as needed.
– Avoid over-handling – Minimize disturbance to the nest during monitoring.
– Close immediately – Reseal box once inspection complete.
– Follow-up checks – May look for evidence young fledged successfully later in season.
Proper monitoring provides valuable data on merganser populations and productivity while minimizing disturbance to the nesting birds. Caution and proper training are required.
How often should merganser nest box maintenance be performed?
– Clean out old nesting material each fall/winter – Debris and parasites can accumulate, deterring reuse.
– Make any structural repairs in late winter before breeding season.
– Install fresh wood shavings or sawdust in the bottom of the box after cleaning.
– Scrape out hardened nesting material if necessary. Avoid harsh chemicals.
– Check and replace predator guards as needed.
– Consider annual painting/staining for long term durability, avoid treating interior.
– Check poles/structures and repair as necessary.
– Remove vegetation obstructing entrance hole or blocking access to the box.
Performing thorough maintenance annually improves merganser acceptance of the box for nesting again the following spring. Well-maintained boxes can be utilized for many years by generations of mergansers.
Benefits of Merganser Nest Box Programs
How do nest box programs help conserve merganser populations?
Merganser nest box programs provide many conservation benefits:
– Boost reproductive rates – Nest boxes support larger clutch sizes and higher brood survival.
– Provide nest sites – Offset declining natural cavities due to development, logging and competition.
– Allow research – Banding and tracking of box-nesting mergansers builds population knowledge.
– Protect from predation – Boxes keep eggs and ducklings safer compared to ground nests.
– Manage habitat – Boxes allow breeding pairs to be supported in desired habitat locations.
– Increase populations – More surviving young means more breeding adults in future years.
– Educate the public – Nest box trails provide opportunities to engage people and improve awareness.
By supporting improved breeding success, nest box initiatives are a valuable tool for bolstering merganser populations, conducting research, managing habitat, and educating the public.
What species of mergansers benefit the most from nest boxes?
The Hooded Merganser depends on cavities for breeding more than the other merganser species and thus benefits the most from nest boxes.
Factors making Hooded Mergansers especially reliant on nest boxes:
– Strong preference for cavities – Rarely nests anywhere else besides tree hollows.
– Suffer cavity shortages – Lack of large hollow trees in many habitats.
– Competition for sites – Breed later when natural sites already occupied.
– Use smallest spaces – Can utilize small box dimensions.
– Tolerate human activity – Will nest in areas with recreation and homes.
– Cavity dependent duckling stage – Hooded young can’t climb up from ground nests.
Providing plentiful artificial cavities helps Hooded Merganser populations persist and expand their range into new areas where natural hollows are scarce.
Case Studies of Successful Merganser Nest Box Programs
Lake Christina, Minnesota
Lake Christina in west-central Minnesota has hosted a successful merganser nest box program since the 1980s. The 220 acre lake is managed as a Fish and Wildlife Management Area by the Minnesota DNR.
Here are some program highlights:
– 37 nest boxes installed along shoreline.
– 25-30 boxes used per year by Common Goldeneye and Hooded Mergansers.
– 150-300 Hooded Merganser eggs laid annually.
– 100-250 ducklings hatch per season.
– Duckling survival rate raised from 2% to 60% thanks to boxes.
Strategic placement of nest boxes has allowed Hooded Merganser numbers to increase substantially despite heavy recreational usage of the lake. Monitoring provides banding opportunities to track birds.
| Year | Hooded Merganser Pairs | Hooded Merganser Young |
| 1986 | 8 | 48 |
| 1996 | 32 | 225 |
Mississippi National River and Recreation Area
This National Park Service site protects 72 miles of the Mississippi River near the Twin Cities in Minnesota. The park has installed around 100 nest boxes for Hooded Mergansers and other cavity nesters along backwater sloughs and pools.
Program successes:
– Avg 30-40 boxes used by Hooded Mergansers annually since 1990s.
– Over 2,500 Hooded Merganser eggs recorded over 30 years.
– Avg 150-300 ducklings hatch per year.
– Duckling survival improved from 1% to 40%.
– Provides banding research opportunities.
Nest boxes have aided the rebound of breeding Hooded Mergansers in the Twin Cities after population declines in early 1900s. They now thrive at this urban national park site.
The Future of Merganser Nest Box Efforts
What are some expanding applications for merganser nest box initiatives?
Beyond basic breeding habitat support, some expanding uses of merganser nest box programs include:
– Urban areas – Installing boxes along waterways in city parks and other urban greenspaces. Provides educational opportunities.
– Reintroduction sites – Using boxes to help establish or reestablish merganser populations in suitable habitat.
– Floodplain habitats – Adding boxes in riparian habitats prone to seasonal flooding. Raises nests above water levels.
– Transitory habitat – Placing temporary nest boxes that can be relocated as habitat conditions change.
– Alternative predators guards – Experimenting with simpler or more effective entrance hole guards.
– Artificial duckling exits – Modifying box floors to allow exit holes to water.
– New monitoring technologies – Using motion-activated cameras or microphones to document activity. Reduces disturbance.
As merganser nest box initiatives mature, new innovations and applications will continue improving the techniques and expanding the potential for these programs to support merganser conservation.
Why should merganser nest box programs continue receiving support?
Despite the long history and proven value of merganser nest box efforts, they should keep receiving conservation support because:
– Merganser populations face ongoing risks – Habitat loss, recreation pressures, lack of nest sites.
– Nest boxes remain a key management tool – Provide artificial habitat augmentation unattainable through other means.
– Each site requires tailored oversight – Proper placement, monitoring and maintenance key to success.
– Dedicated volunteers and funding needed – Programs depend on committed individuals and financial backing.
– Important for both common and threatened species – Supports Hooded Mergansers along with other cavity nesters.
– Educational and research opportunities – Allows public participation and advancing scientific knowledge.
– Benefits wider landscapes – Production of ducklings supports surrounding ecosystems.
Continuing nest box initiatives remains a simple, effective approach to sustain thriving merganser populations and advance related conservation, education and research.
Conclusion
In conclusion, the use of nest boxes is an important conservation strategy for certain merganser species, especially the cavity-dependent Hooded Merganser. Nest box programs help provide critical breeding habitat, increase reproductive success, facilitate research, and allow better population management. Pioneering merganser nest box initiatives started in the 1960s and have expanded across North America. With proper placement, dimensions, and annual maintenance, nest boxes will remain a key tool in the future management of merganser populations. Support for these proven conservation efforts should continue through dedicated volunteers, agencies, and funding sources.
