Listening to What Birds are Telling Us About Sustainable Forests in East Texas
Technology is pointing the way toward a new measure of sustainability in the management of Southern pine forests—neither carbon sequestration nor riparian buffer width nor canopy closure, this measure is one of the oldest and could very well be the broadest overall indicator of forest ecosystem health: the dawn chorus.
Dan Saenz, along with his colleagues, holds the world record for highest sound recording of an amphibian at 17,500 feet in the Peruvian Andes (a study of glacial retreat). Saenz is a research biologist who has been using “frog loggers” to automatically and remotely record frogs since 2000. He began recording from eight sites in Texas in May 2000, and he’s now recorded six times per day every night for 20 consecutive years!
Wild Turkey and American Kestrel
Dr. Saenz’s lab at the US Forest Service Southern Research Station in Nacogdoches, Texas also monitors birds, and in 2019 he was tapped by representatives of the Texas Longleaf Implementation Team and the Lower Mississippi Valley Joint Venture (LMVJV) to help determine bird response to pine forest management in east Texas.
“When they first approached me, I said I could do it,” Saenz explains, “but only if we could use autonomous recording units (ARUs) to conduct the monitoring.”
When is listening better than seeing? How can a form of monitoring that excludes visual sightings of quiet birds be superior to one that relies on sight and sound? “When it’s listening relentlessly at the same time every day for years,” answers Saenz.
Consumer demand for sustainable forest products has a real impact
Birds have long been monitored to assess wildlife response to habitat management. In recent years, as the timber industry has undergone large changes in land ownership and as consumers have become more ecologically aware, the demand for timber and pulp products from sustainably managed forests has grown.
Jeremy Poirier, Fiber Sustainability Manager for International Paper (IP), explains, “About 15 years ago, IP was probably one of the largest private landowners in the U.S. with six million acres.” By 2006, as part of a larger tectonic shift in ownership of U.S. timberlands, IP had sold all of its timber properties.
Although its land ownership status radically changed, its concern for sustainability did not. “We’re one of the largest consumers of pulpwood in the world with paper mills all over the U.S. and in other countries. A lot of our end customers require certification showing their materials were sustainably sourced. In fact, as a global forest products company, we say our entire business depends on the sustainability of forests.”
The IP supply chain starts with private landowners, many of whom were the purchasers of timberlands in the early 2000s. “A large percentage of our pulp comes from small nonindustrial landowners,” explains Poirier, “especially in the South, where they own 60% of forestland.”
Some counter-intuitive aspects of sustainable forest management
“The timber industry gets a bad rap for not being wildlife friendly, which is not the truth,” says Don Dietz, a certified wildlife biologist who works as a coordinator for the Sustainable Forestry Initiative (SFI), one of the three main third-party forest certification programs in the U.S. Dietz oversees sustainability practices on over one million acres in east Texas and Louisiana. His primary role for SFI is to inspect and verify that cuts are conducted sustainably.
“As you clearcut a pine stand, you may be ruining habitat for birds that like deep woods, but you are creating habitat for another suite of birds that rely on early successional habitat.
“Then prior to a first thinning at about 12 to 13 years, the woods get thick again for wood thrushes. Thinning is conducted in rows, which benefits game birds such as bobwhite quail and wild turkey, then the woods thicken again and when the stands are 18 to 20 years old, there is a second thinning, and another suite of birds comes in.”
Photos top row: Prairie Warbler, Painted Bunting,Brown-headed Nuthatch by James Childress
Photos middle row: Red-cockaded Woodpecker, Bachman’s Sparrow by James Childress; Northern Bobwhite by Don Dietz
Photos bottom row: Texas longleaf savanna in fog by James Childress; Prescribed burn in longleaf, Longleaf 6 months after a burn by Simon Winston
All the birds shown benefit from prescribed fire in open pine forest habitats.
In addition to timber harvest and thinning, every year large swaths of pine forest across the South—longleaf, shortleaf, and to a lesser extent, loblolly—are burned on purpose, a carefully managed activity known as prescribed fire that is undertaken by forest managers, private landowners, and conservation groups.
This practice is a substitute for the fires that once burned naturally and without suppression—set by lightning or Native Americans—in the millennia prior to European settlement.
“Why do I burn to keep my forest open?” asks Simon Winston, the owner of the award-winning Winston 8 Ranch in east Texas. “When my father started burning in our longleaf, it was strictly 100% for the pine timber, to control the invasive plants that take away from the pine tree growth. The more you knock down all the sweet gum and yaupon that takes away from the pine, the faster the trees grow, and the more money you make. But burning made things a lot better for wildlife too. After you burn, the green stuff comes back in, new shoots that are high in protein for deer, and the bluestem native bunch grasses make better nesting for turkey and quail.”
Answering the critical question
Turns out that one of the best measures of wildlife response to land management practices such as prescribed fire is bird response—both the diversity and type of species as well as their abundance.
Over time, everyone involved in open pine restoration in Texas has found themselves itching to answer this question: Are birds actually benefiting from our conservation efforts in open pine?
Beginning in 2019, and scheduled for completion in 2020, an array of 32 song meters have been recording bird songs at 10 longleaf sites in east Texas and at 22 sites in loblolly and shortleaf pine habitat (all of which are collectively known as “open pine.”) They are located on a total of four separate properties (three private and one on the Angelina National Forest), each defined by a 200-meter buffer (radius) of habitat that includes only one stand type, defined by parameters such as tree species, stand age, and time since last prescribed burn.
The song meter recorders are set to come on at 30 minutes after sunrise and one hour after sunset for 10 minutes each time, every single day spanning the entire breeding season—approximately three months from April through June.
The data gathered will show how birds at various sites have responded to well-accepted management practices, such as prescribed fire. While all pines are fire-adapted, some such as longleaf and shortleaf are much more tolerant than others such as loblolly.
While monitoring of conservation projects is an integral part of the Joint Venture’s approach and indeed that of many conservation groups, the reality is that monitoring usually gets short shrift. It’s the afterthought that will be implemented when funding allows, which it often does not.
However, National Fish and Wildlife Foundation grants, many of which support the pine management work, require monitoring of results.
Keith McKnight states emphatically, “The JV partnership objective is not to apply textbook-accepted remedies such as fire to bird conservation. Our objective is to conserve bird populations and increase them. Ultimately we are not evaluated on what percentage of our management activities are consistent with the literature. Instead we have to answer the question, did you have an impact on the population?
“NFWF and other funders say ‘Thank you for the acres restored and the matching funds, but did you do anything for the resource you said you were going to benefit?’ That is the focus of our song meter project.
“Our partnership focuses on landscape conservation and a healthy landscape, but ultimately, to measure the health of a landscape you do have to look at species!”
The priority bird species that are a focus of conservation in the region include:
• Eastern wild turkey (Meleagris gallopavo silvestris)
• American kestrel (Falco sparverius paulus)
• Red-cockaded woodpecker (Picoides borealis)
• Northern bobwhite (Colinus virginianus)
• Red-headed woodpecker (Melanerpes erythrocephalus)
• Prairie warbler (Setophaga discolor)
• Bachman’s sparrow (Peucaea aestivalis)
• Brown-headed nuthatch (Sitta pusilla)
• Chuck-will’s-widow (Antrostomus carolinensis)
A “shocking” species accumulation curve
Not only is this research geared toward answering the critical question of how birds are responding to forest management, Saenz also is using it as a pilot to figure out what is a suitable sampling period for monitoring birds with song meters during the breeding season.
The detection probability from one species to the next is not the same. "That’s why recording over time is more effective,” he explains, “you pick up the species such as wild turkey, which are low probability where they do occur, over time.” Other advantages of song meters are the ability to program them to start recording at precise times relative to sunrise and sunset, based on the latitude and longitude of each site.
“I was shocked, after conducting research and sampling birds for many years, at how inadequate previous auditory samples (point counts) have been!” This is the major lesson that Dan Saenz is taking away from this project.
“We’ve learned how much better a bigger sample is. When I ask professionals how many days do we need to collect data to get a good idea of birds at a site, they estimate 3 to 5 days, but we are finding we need at least 15 days of data to get to 90% of all birds recorded.
“The most fun part has been looking at the species accumulation curve over time. If you talk to people who do bird surveys for a living, they average about 10 birds (8 to 15 species) in these open pine habitats. We don’t have a complete analysis yet, but in shortleaf pine, on day 1 we average 10.1 species/site. By day 20 we’ve counted a cumulative mean of 22.8 species/site.
“We are basically building a bird list and learning how long it takes to get one that is relatively complete.”
Surprise!? Bird communities sort by habitat
Avian communities are generally very responsive to habitat changes, so it’s not surprising that Saenz’s team is finding clear patterns in bird response after only one year. “We are finding that bird communities sort by burned vs. unburned habitat very neatly. For example, some species such as Pine Warbler occurred at all sites, while some species such as Brown-headed Nuthatch and Red-headed Woodpecker primarily occurred in sites treated with fire and others such as Hooded Warbler primarily occurred in unburned sites.”
In 2019, they detected a total of 47 different species across 18 sites (more sites were added in 2020). More bird species were detected in the burned sites compared to the unburned sites.
The greatest differences they found between treatments were in the understory vegetation. Burned sites (burned within the past 5 years) had the most abundant and diverse composition of grasses and forbs compared to unburned sites (which were likely burned at some point but had not burned for > five years).
One of the greatest scientific advantages of song meters over traditional point counts is that the recordings serve as voucher samples.
“If there is any doubt about whether a species was actually present, you have a voucher specimen!” exclaims Saenz. “It’s verifiable. Disputed observations from the point counts are too easy to discount. With song meters, I can send the recording file to anyone.”
Listening to what the birds are telling us
Poirier with IP is unequivocal in his support for this project: “It’s really cool, cutting-edge science,” he says. “We are very limited as biologists to be able to go out and sample, but now we have a machine that tells us what’s out there without being there!”
In fact, landowners don’t pay for research like this. That’s why IP helps to fund projects such as these through NFWF's Forestland Stewards program.
What some landowners will do, however, is host scientists who want to study wildlife on their land. That’s the case for Simon Winston, of the 3000-acre Winston 8 Ranch, the site of three song meters.
“I’m interested in all of it. I let people look around because I’m proud of the place and want people to see it, to demonstrate our stewardship. I got all kinds of different butterflies and milkweed, and over 700 different plants!
“I’m real excited to have people come and look at what we have because I’m trying to get east Texas to do more controlled burning. Most of these people who have pine plantations don’t manage it with controlled burns, they let it grow up in invasives. This research is showing that the places grown up with invasives have the least birds too.”
Simon’s voice carries a note of pride when he talks about preliminary results from his ranch, saying, “At my place we have 40-some kinds of birds, one and a half times what everybody else had! We do a lot more controlled burning than many forest landowners to keep the brush down. My woods are open, nothing grows more than knee high except the pine trees."
Bill Bartush, the Joint Venture’s local partnership coordinator in Texas, makes the point that the collaborative conservation work in east Texas—supported by habitat conservation modeling and planning conducted by the LMVJV—all underscore the value of private timberlands in the West Gulf Coastal Plain.
“The results from this song meter project after one year appear to be validating the good habitat management that’s being done on private lands. It’s a success story that really has not been told well enough!
Poirier agrees. “Birds are great because we can see and hear them. They make a great mascot for sustainable forests, because you can’t argue when the evidence is right there in the young forest itself! It’s not me labeling something sustainable, it’s not IP, it’s not a writer, it’s the actual wildlife saying it, in their own voices.”
And now, the birds of southern pine forests are going on record.
Implementation Partners
• Lower Mississippi Valley Joint Venture
• Northeast Texas Conservation Delivery Network
• Texas Longleaf Implementation Team
• Texas Parks and Wildlife Dept.
• USDA Forest Service, Southern Research Station
Funding partners
• National Fish and Wildlife Foundation
• Texas Parks and Wildlife Dept.