As a conservation biologist and forester with Audubon Vermont, as well as a maple syrup producer, I feel like I’ve got pretty sweet jobs. When the Bird-Friendly Maple Project, which brings bird conservation and the maple community together, was developed it was the obvious choice for my family maple operation to be a part of it. I would like to share with you what the project means for me and how it has helped shape my own sugarbush management.
Setting the stage
For many Vermont is synonymous with maple syrup, and for good reason. Each year the Green Mountain State produces nearly half of US production. Fewer people are aware that the same forests that support the maple industry also provide nesting habitat for some of the greatest number of bird species as anywhere else in the country. The Bird-Friendly Maple Project was developed in 2015 through a partnership among Audubon, the Vermont Maple Sugar Maker’s Association, and Vermont Department of Forests, Parks, and Recreation as a way to integrate and promote these two aspects of our state’s forests. I would like to point out right up front that in my view all sugarbushes are inherently good for birds. Sugaring keeps forest as forest, the loss of which is among the greatest threats to birds. How our sugarbushes are managed however can make the difference between them just being ok or serving as high-quality nesting habitat where birds successfully raise their young. For myself and the other 50 producers around the state who currently have pledged to manage their sugarbushes with birds in mind comes a marketing benefit. Unique labeling, signage, and other promotional materials helps us to inform our customers that we are participating in an intentional effort to conserve birds and their habitat while making the world’s best maple syrup.
What do the birds need?
As a child I used to draw pictures of trees with a bird nest right up at the top. Turns out that’s not the way it really works. Different bird species can reliably be found nesting and searching for insects to eat at all levels of the forest; from directly on the ground to almost the upper canopy. The majority of them fall somewhere in the middle. To meet the nesting habitat needs of a variety of birds it is important to make sure that a variety of tree sizes exist in your sugarbush.
Seedlings, saplings, and shrubs growing within the first 6 ft of the ground in dense patches create the understory layer where birds like Black-throated Blue Warbler will be found. In my sugarbush American beech makes up the majority of the understory along with scattered striped maple and red spruce. It would be great if I had some other plant species in there from an overall forest health perspective (the birds don’t care as much) and that is one of the goals of my forest management.
Larger saplings, smaller pole sized trees, and even lower branches of bigger trees in the 6-30 ft height range form the next layer; midstory. In most of my sugarbush this habitat feature is pretty well established making it a perfect place for Wood Thrush and Red-eyed Vireos to nest. I hear the songs of both of these out there on a regular basis. Once again however American beech is the primary species and this leads to concerns around the future of the forest and the diversity, or lack thereof, of tree species that will define it.
When looking to establish and manage a maple sugarbush the abundance of sugar and red maple is logically an important consideration. It’s difficult to rationalize a forest with 10-20% maple as a sugarbush. My sugarbush is currently only about 37% sugar and red maple combined. The remainder is a mix of associated hardwoods such as American beech (again!), white ash, yellow birch, aspen, red oak, basswood, and the like. There is also an eastern hemlock component. Although this is not the forest composition that many would choose for a sugarbush, for me it was just about perfect (except for the predominance of beech!) Why? Because a diverse tree species composition supports a more diverse bird community and an overall healthy forest. What I may sacrifice in near term sap production I believe is more than made up for when I consider the long term health and integrity of the forest. My plan is to continue to support tree species diversity through management, including promoting the growth of those red spruce currently residing in the understory and the eastern hemlock in the midstory and upper canopy. The presence of softwoods is the main reason I have Blue-headed Vireo and Blackburnian Warbler in my sugarbush – two of the species that associate heavily with conifers. The yellow birch and red oak support high insect diversity, a critical food source for the birds during the nesting season.
Last week while doing some birding in my woods I came upon a number of dead trees that had fallen over, taking down the lateral lines in doing so. I’m guessing many of you who are maple producers have come across this a few times as well. My initial reaction was (expletive) more work to do! This was quickly followed however by an appreciation for the coarse woody material (read logs on the ground), an important habitat element for Ruffed Grouse, which was added to the sugarbush. Before many of those trees came down they were standing dead, also called snags. Pileated Woodpeckers and other cavity nesting birds need them for raising their young as well as searching for an insect meal in them. I admit that sometimes I get irritated by snags and large branches falling onto my tubing system, creating yet more work to do in clearing them and repairing the lines. In those situations it helps to remind myself that I’m working within a forest ecosystem and maple is a forest product. This forest system is doing just what it is supposed to be doing and I need to work with it, not against it.
Silviculture with birds in mind
Creating the best bird habitat AND sap yields I can doesn’t happen overnight or in most cases on its own. Active forest management including the use of appropriate silvicutural treatments is of utmost importance to achieving my sugarbush management goals. I am currently in the process of updating my 10 year current use forest management plan and am actively thinking about how to best integrate my goals for bird habitat with sap production. Based on the data collected during the forest inventory one of the treatments I’ll be prescribing is taken from Silviculture with Birds in Mind, a guide developed as part of another Audubon/Vermont Dept. of Forests, Parks, and Recreation partnership called Foresters for the Birds.
A commonly used treatment in sugarbushes is crop-tree release (CTR). The idea is to identify upward of 70 trees per acre that you want to keep (the “crop” which are typically maples) and enhance their growth of by harvesting trees around them that have their crowns touching the crop tree (the release). This provides the crop tree with room to grow and in turn producing greater quantities of sweeter sap. In a slight variation on this I’ll be prescribing crop-tree release with canopy gap formation. The crop tree release part remains the same. My crop trees will be maple as well as other tree species with high habitat value such as red oak and yellow birch. In addition between crop trees I’ll create circular canopy gaps ranging from 30-75 ft in diameter. Within these gaps all poor quality stems >1 in DBH (diameter at breast height) will be cut. The purpose of adding the canopy gaps is to help stimulate the understory growth mentioned earlier. In the process it is highly likely that I’ll end up cutting some diseased and damaged maples (gasp!). It’s a true win/win/win silvicultural treatment for increasing sap production, enhancing habitat structure, and improving overall forest health.
Not just for the birds
As a bird conservation organization Audubon Vermont has a mission to protect birds and the places they need today and tomorrow. The Bird-Friendly Maple Project is working to do just that, and more. Conserving forest birds is dependent upon a healthy forest and a vibrant forest economy. Audubon believes, as do I personally, that managing a forest with birds in mind yields numerous additional co-benefits. Among these are greater resilience to climate change and carbon storage potential, a buffer against the negative impacts of non-native invasive insects, and clean water. Bird-Friendly Maple is a story that promotes Vermont’s maple industry and the excellent forest stewardship that surrounds it. It brings consumers into bird conservation through their support of maple producers who have made the choice to intentionally add birds and their habitat into their sugarbush management. In today’s world conservation is an “all hands on deck” job!
I’d like to invite maple producers and those who love maple products to join me in the Bird-Friendly Maple Project. I think you’ll find it’s a pretty sweet deal!
For more information visit https://vt.audubon.org/maple or call Audubon Vermont at 802-434-3068.