(This page is a subpage of nsforestnotes.ca/Natural History/Birds/2022 Bird Study)
The Scientific Article
Forest degradation drives widespread avian habitat and population declines
by Matthew G. Betts et all, 2022 in Nature Ecology & Evolution. The full text is publicly available
In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2 ) which, in turn, has caused bird-population declines. Despite little change in overall forest cover, we found substantial reductions in old forest as a result of frequent clear-cutting and a broad-scale transformation to intensified forestry. Back-cast species distribution models revealed that breeding habitat loss occurred for 66% of the 54 most common species from 1985 to 2020 and was strongly associated with reduction in old age classes. Using a long-term, independent dataset, we found that habitat amount predicted population size for 94% of species, and habitat loss was associated with population declines for old-forest species. Forest degradation may therefore be a primary cause of biodiversity decline in managed forest landscapes.
Bird populations in eastern Canada declining due to forest ‘degradation,’ research shows
Article by Steve Lundeberg for Oregon State University Apr 28, 2022. The lead author of the study reported in Nature Ecology & Evolution is Matthew G. Betts, a member of the OSU College of Forestry; he was interviewed by Lundeberg. From the article:
“Due to increased global demand for wood, more and more of the Earth’s surface is being used for timber extraction,” said Betts, the lead scientist for the HJ Andrews Long-term Ecological Research Program. “This shows up on remote sensing as both forest loss and forest gain, but unfortunately the ‘gain’ is often vastly simplified, young forest. Our paper presents a new way to quantify these sorts of changes.”
Betts and collaborators from Cornell University, the University of Rhode Island, the University of New Brunswick, Google and multiple Canadian and U.S. agencies combined satellite imagery and breeding bird survey data along with species distribution modeling to examine forest and bird population trends.
The Acadian Forest, known for its tree species diversity, has shown pervasive signs of degradation over the last three-plus decades, Betts said. Since 1985, more than 3 million hectares of the Acadian Forest have been clearcut, and much of that area is now dominated by single tree species or a mix of early successional species.
“Old forest declined by 39% over the period we observed,” Betts said. “Over the same period, forest cover actually increased by a net 6.5%. That pattern of extensive harvest of old forest, followed by rapid regeneration of young forest and then subsequent harvest before maturity is attained, seems to be common in many forest regions of North America and northern Europe.”
…Species experiencing the greatest decreases in habitat were the golden-crowned kinglet and Blackburnian warbler, with seven species in all showing habitat declines of greater than 25%.
…“Overall, our findings indicate broad-scale declines in forest birds of the Acadian Forest, and for most species, abundance is strongly associated with habitat amount,” he said. “We expect that similar consequences for biodiversity are in place for intensively managed forests in other parts of the world as well. If all you look at is forest cover, you’ll miss the more subtle but critically important role of forest age and type in maintaining biodiversity.”
– Replanting one type of tree is not enough to stop clearcutting harm, study finds
Hadeel Ibrahim · CBC News, Apr 29, 2022 “Betts said the good news is New Brunswick and Nova Scotia are on the cusp of major policy changes that can help bird populations. “The number of protected areas in New Brunswick is going up,” he said. “Also, we’re moving more toward different forestry practices that don’t involve clearcutting and replacing with conifers, but more focusing on maintaining the type of forest we’ve got.” He said even if forestry practices are changed fundamentally right now, populations may still decline for a while before the benefit is seen. “We’re going to keep an eye on that and keep going along with the research.””
– Bird populations declining in the Maritimes (Audio)
CBC Shift-NB hosted by Vanessa Vander Valk “Forest degradation is driving declines in bird habitat and populations in the maritimes. That’s according to a new study released today in Nature Ecology and Evolution. Matt Betts led the research. He’s a Professor of Forest Ecology at Oregon State University and a New Brunswicker.”
Below is a rough transcript of the interview.
|VV: Forest degradation is driving declines in bird habitat and populations in the Maritimes. That’s according to new study looking at the impact changes to the Acadian forest or having on birds the study was released today in Nature Ecology and Evolution. Matt Betts led the research. He’s a professor of forest ecology at Oregon State University and a new Brunswicker and he joins us on the line.Good afternoon…So what were you trying to find out with this study what were you looking at? it could be losing
Well a paper came out a couple years ago showing broad scale declines in birds across North America but one thing that paper didn’t answer was what the causes of those declines are.
One hypothesis we had was that it could be due to more subtle changes in the forest over the last 35 years and species could be losing habitat which would be driving populations downward.
VV: So how did you look at that issue? What information were you able to access?
MB: Two big datasets really played into it. One was remote sensing data, so data from satellites 705 kilometers in space scanning the earth surface. So we had wall to wall data for all the Maritime provinces in terms of what the forest looks like. And and then we had an amazing data set collected by New Brunswick and Nova Scotians and people from PEI on bird distributions. Believe it or not people went out to 11,000 places across the Maritimes and counted birds and so we were able to measure habitat for 54 bird species using these satellite data and then we back cast to 1985 when I was around 15 years old and growing up just outside of Saint John and we quantified how habitats declined since 1985 to the present time.
VV: And what did you discover about the change in bird populations over that time?
MB: We were a bit surprised in a way. We expected mature forest-associated birds, so birds that like old old forest, not to be doing too well because we’ve been harvesting it so much. But in total, about 94% of species showed some degree of habitat decline, net habitat decline, and populations tracked those declines, for some species declining at rates about 70%. And those declines are linked to declines in habitat… We estimated about 28 million hectors of habitat has been last over the 35 year time frame and that equates to about 100 million birds at the top and at the lower end of about 35 million birds over that period.
MB: That’s a really good question and one we thought really carefully about. So, similar to amphibians, you know tons of things drive bird population declines; what’s happening on wintering grounds in South America, for example, or pesticides directly or a whole suite of things can drive declines.
But we did what’s called a natural experiment where we we quantified the amount of habitat along these breeding bird survey routes, 90 of them in total, and we said the routes with the most habitat decline should be showing the greatest population decline. So for our results have occurred due to some other reason, you would have to have that other cause tracking with the exact same magnitude as habitat loss along those routes, which is extremely unlikely; and of course we can’t do experiments at the scale of entire provinces like true experiments with controls but this is as close as it can come to being a strong effect and being able to point to cause as you get with the research happening at this scale.
VV: How have the forests in our region changed over that 35 year period?
MB: I bet a lot of your listeners will recognize this, but overall we’ve seen a big decline in older forest. I’m not talking about old growth just mature forest and it has declined at about 40% over the 35 year period. So a substantial drop. And then also the forest that’s replacing it is generally a planted forest or intensively managed by thinning and that’s different. You can notice it when you drive along the highways that often the planted forests are coniferous and the forest that is being removed is mixed diverse forest, what we call Acadian forest so red spruce and sugar maple and yellow birch.
VV: A big change!
MB: That’s the major change; we’re changing from a diverse older forest to a younger more monocultural forest.
VV: You saw you know impacts across a number of bird species but which species have been most affected here?
MB: There is one species in particular which I think will end up being akind of a poster child for Acadian forest change, and that’s blackburnian warbler. A lot of people haven’t seen it. It’s a little migrant songbird with a bright orange face. It’s declining at a rate of about 70%.
But then even some other common species that the listeners might have seen or heard, olive-sided flycatcher, for example, Swainson’s thrush, winter wren’ they are all or declining at rates greater than about 50% over that period of time.
VV: What effect might this research have on current forestry practices?
MB: Thereis a good news story here and I think New Brunswick and Nova Scotia both are on the cusp of having some pretty major policy changes that could help bird populations. So, for example, the number of protected areas in New Brunswick is going up, people in Natural Resources are focused on that.
And also were living more toward different forestry practices that don’t involve clear cutting and replacing with conifers but more focusing on maintaining types forest we’ve got.
So I’m somewhat optimistic they will continue with those policies and those policies will go through and if so I think we can expect that some of these declines would slow down. But if we continue in the direction we’re going right now, I am a lot less optimistic.
VV: Is that change happening fast enough for your warblers and your thrushes?
MB: Stay tuned. I think the next 6 to 12 months, we’ll really have an idea about whether that change is happening fast enough. You know one concern that ecologists have are things that are called lags, temporal lags. So what does that mean? It means that these populations could keep declining even after we’ve solved the problem for a while. And so we’re going to keep an eye on that and keep going along with research. But at the very least, we need to change some of our core forestry practices; focus more on maintaining those nice colourful Acadian forest species we have.
VV: There are of course a lot of people in this province and beyond who are very interested in birds, a lot of birders who do spend their spare time counting birds and looking at bird populations and this is a real fascination of their’s. Beyond those people and those birds, what’s the bigger picture? Is there a larger worry here beyond what’s happening with bird populations?
MB: That’s a really good question and many people ask me why I spend so much time studying birds, who really cares about birds? But a couple of important things to remember here: one, this is one of the only long-term datasets we have for any species at all; and because people like birds as you point out, people have counted them for decades. So what’s going on with flying squirrels or what’s going on with the beetles or large mammals? We don’t really have an idea. Deer are really the only species we do know something about how they’re trending over time. So the concern is that it’s not just birds that are exhibiting this pattern but all across different species groups.
And people have been taking about birth as indicators for thousands of years, you know going back to the Canary in the coal mine etc even the ancient Romans. And so I would say that if we’ve got brd declines like this, it’s potentially symptomatic of other problems environmentally which we need to fix. Of course the other one is that birds are well known for providing ecosystem services. So what does that mean? It means they eat the insects that eat our trees. So we really need to look after the populations to maintain some of those services so we get bitten by mosquitoes and black flies less.
VV: Thanks so much for telling us about the research today…Matt bats is a professor of forest ecology at Oregon State University and a New Brunswicker. He was the lead of a study published today in Nature Ecology and Evolution that looking at the impact of forest degradation on bird populations.
Text as submitted below.
CONSIDER THE BIRDS::
Almost a year ago today, two tiny Barred owl chicks and an unhatched egg were rescued from a tree that had just been felled during forestry work. Fortunately, someone made the effort to have the owlets transported to Hope For Wildlife where they were successfully raised. As we head into yet another nesting season, and as both overwintering and incoming migratory birds take up residence to produce the next generation of offspring, this scene will be repeated again and again as a direct result of forestry operations. Some, like tiny owlets, will die as they fall out of, or are crushed in nests destroyed during tree felling and chipping operations. Others will die due to the disappearance of the specific type of forest needed for the parent birds to successfully build well-concealed nests and find an adequate supply of food for their young. Many species of birds exhibit a high degree of “nest-site fidelity” – returning annually to the same grove of trees to build nests, forage for food, and seek shelter from predators. Who among us has not seen evidence of birds returning to nest in the very same spot, year after year? Now imagine the stress and disorientation to incoming migratory birds, having just completed flights of hundreds to thousands of kilometres, only to find their familiar grove of forest chopped down and reduced to a wasteland of slash and muddy ruts.
In the past, I and others have been told by those who should know better, that forestry operations are good for the birds and that it is cat predation and window collisions that are the real culprits and cause of declines in bird species populations. While both are serious threats, habitat destruction and bird deaths due to large scale forestry operations are right up on top, especially in those species that require mature forest to nest — exactly the same type of forests that are so highly prized for logging. These are the forests that, over the past three decades, have seen the greatest pressure and are now dwindling to almost nothing in many areas of our province. A recently released paper, “Forest degradation drives widespread avian habitat and population declines” by Matthew G. Betts and al., (Nat Ecol Evol (2022), is based on studies in Acadian type forests right here in the Maritimes. The conclusion is not something to be proud of. Our Acadian mixed forests have become severely degraded and, in many cases, “replaced” with coniferous softwoods or monoculture conifer plantations which are entirely unsuitable habitat for a good number of forest-dwelling bird species. Accordingly, populations of bird species that depend on Acadian type forests are dropping in sync with forest loss.
Those of us who express our concerns about forest and habitat loss to the government, have been repeatedly dismissed. We are basically told, “Go away! Everything is fine! We know what we’re doing!” Now we’re being told that the “new way” of doing forestry on public Crown lands, will soon be starting, so all will be wonderful. Meanwhile, previously approved parcels on Crown land are being madly chopped and hauled away before the June 1st deadline when the “new way” will kick into effect. In addition, what the government fails to make clear is that it has still not designated the “protected” forests that will be set aside for the survival of wildlife and preservation of biodiversity. In the interim, more forest parcels continue to be approved for cutting — yes, now under the “new way” — but that’s not doing much good as far as ensuring that suitable habitat is being preserved for migratory birds and other creatures. So, no, all is not fine! We must remember that certain kinds of mature forests are necessary (not optional!) for the survival of many species of birds such as those that require hollow “cavity trees” or certain canopy heights, or particular mosses from which to build nests. Not just “any forest” will do. When will those in power acknowledge this truth? As we wait and wait for the “old forests” to be protected as vital wildlife habitat, are they, in fact, going down for the count?
Under Canada’s “Migratory Birds Convention Act”, it is illegal to destroy, harass or disturb migratory birds and their nests. Yes. Illegal. However, until things change, that is precisely what is going on in our province every day throughout nesting season. Somewhere, bird nests, eggs and hatchlings are being destroyed. When will we see the kind of change that needs to happen to prevent further death and destruction?
PHOTO:: Barred Owl chicks and unhatched egg rescued from a felled tree — photo by Donna Crossland (with permission).
Forest degradation drives losses of bird habitat and population
Bob Bancroft in N.B. Media Coop, May 9, 2022. “Habitat demise can be traced back to governments with ecologically-unfriendly silos of departmental responsibility. Species like Atlantic salmon are jurisdictionally insulated from forestry activities that turn watersheds into overheated wastelands. Employees can only operate within their department’s jurisdiction. The collective will and means to deal effectively with serious ecological issues are rarely mustered…If citizens want healthy forests and robust wildlife populations, the time has come for drastic change. We’d better start now. With eastern forest landscapes and wildlife populations deteriorating rapidly, the path to recovery will be long and costly.”