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Study from SUNY ESF Explores Human Impact on Vertebrates Humans Responsible for the Death of over a Quarter of Vertebrates in Study

By Cole Weinstein

Jerrold Belant works at his desk
© 2019 Cole Weinstein

Sam: A study from a local college states that around 12 thousand vertebrates or animals with spines were killed directly at the hands of humans since 1970. Reporter Cole Weinstein investigates why this study broke new ground.

Cole: The study from the SUNY college of Environmental Science and Forestry found the number of dead animals due to humans to be over 25 percent of the approximately 43-thousand dead vertebrates. The total number of vertebrates studied is over 120-thousand. Postdoctoral researcher at E-S-F, Jacob Hill, says the study explored new territory.

Jacob: That hasn’t previously been quantified. It’s been assumed that the direct human mortality of vertebrates is quite large, but no one has ever systematically measured that.

Cole: Advisor on the study, Jerrold Belant says this is more proof of human impact on the planet for those who doubt it.

Jerrold: What it is, is just one more piece of quantified evidence that humans are having major impacts on our environment.

Cole: This study doesn’t just introduce new evidence. Hill says data from the study can be narrowed down and used to answer other questions about human impact on other vertebrates.

Jacob: You could also do a lot with the database, like species-level analysis. So, if you’re just interested in how much a particular species is dying you could easily go into that database and pick all the studies from that species and do an analysis with that.

Cole: Hill is expanding on this study by comparing the death rates of animals in government protected areas versus privately owned land with no protection. Protection from human actions that might have harmful effects on the land.

Jacob: It has some kind of protection where you can’t just go there and just deforest all of it or do something like that. That’s opposed to just privately-owned land somewhere. So those area’s do have some degree of habitat protection.

Cole: Animals used in this study were only tracked using radio telemetry. Research and wildlife biologist for the USDA, Travis DeVault, says it is an umbrella term for different types of technology that monitors animals remotely.

Travis: Whether it’s radio waves or GPS or what have you. All of these animals were monitored remotely through some kind of radio telemetry technology.

Cole: DeVault says he chose vertebrates for his research because of the lack of studies and tags on animals without spines.

Travis: The easy answer to that is there aren’t very many radio telemetry studies for animals other than vertebrates. So, it’s really a matter of the data that we had.

Cole: The study was published in the scientific journal Global Ecology and Biogeography. Hill says the biggest criticism from the journal during the editing process regarded the uncontrolled factors in his study.

Jacob: So, I had to more fully acknowledge those and then they also wanted to run my analysis for outside of North America. When I submitted the draft originally, I just did an overall analysis and they wanted those additional analysis outside of North America.

Cole: Hill said having a majority of his sample size from North America had an impact on how the study was edited.

Jacob: The data set is so heavily biased towards North America that if you include stuff outside North America, we’ve had some issues with the reviewers saying the studies are so sparse outside of North America that you can’t make good conclusions off of that.

Cole: Hill says the numbers could be different with a greater sample size.

Jacob: In terms of that number like 28 percent of mortality being the result of humans, I don’t know if that would be the case if other things were included or if other parts of the world were better represented.

Cole: Despite the heavy focus on North American animals, the data collected outside the continent showed similar results, says DeVault, who was also a research consultant for the study.

Travis: Because so many of the studies were from North America, we looked to see if the studies outside of North America, those that we did have, differed in their findings from the study as a whole and we did find that many of the trends were the same.

Cole: Hill says other flaws in the study include the lack of some animals. Primates were not in the study and neither were bats.

Jacob: They’re also just pretty small and also haven’t been well studied until pretty recently. So there’s just not many studies on those either.

Cole: Hill says that not all the editing feedback from the journal was on the research itself.

Jacob: A lot of your comments are just people’s opinions like ‘I don’t like this word choice, I don’t like this sentence, reword this.’ So, a lot of people’s comments are nitpicky stuff like that.

Cole: DeVault says despite the flaws he doesn’t want people to ignore the study.

Travis: I don’t want to downplay the significance of the findings because this is the best information that is available right now so even though some areas and some groups weren’t covered, I think the information that we do have is pretty enlightening.

Cole: Belant also says the big picture look at human impact on vertebrates is more important than specific numbers.

Jerrold: Though the numbers are probably not exact, almost certainly not exact it brings the point across that we’re having a major direct impact on terrestrial vertebrate mortality worldwide.

Cole: Belant even argues the numbers on this study are conservative.

Jerrold: Because we are only looking at direct human-caused mortality not indirect. For example, alteration of habitat or land use change could and has been demonstrated to result in increased vulnerability of some species to predation risk.

Cole: Belant said he and DeVault gave a lot of advice on this study.

Jerrold: The advice ranges everything from project conception and design, how to approach methodologies, how to tackle the potential biases, through analytical approaches through the writing and publication process.

Cole: Hill says the work is not done. The data found in this study can be expanded by him and other researchers to further explore the death of vertebrates and the impact of humans on the environment.

Cole Weinstein, NCC News

By Cole Weinstein SYRACUSE N.Y. (NCC News)

A study out of the SUNY College of Environmental Science and Forestry examined the impact that humans have on vertebrates or animals with spines. The research found that around 12,000 of the approximately 43,000 dead vertebrates were killed at the hands of humans since 1970. That means that over a quarter of all dead animals in this study were killed directly at the hands of humans.

Advisor on the study, Jerrold L. Belant, says a goal of the study was to show the effect humans have on the planet to the public.

“We simply wanted to alert the world relative to the effects we’re having. We talk about a lot of indirect effects; climate change is a huge topic,” said Belant.

Belant says the study exists not as a way to measure dead vertebrates, but instead to show a big picture look at human impact.

“It’s not even so much a trend, it’s a point in time if you will like a snapshot, but what it demonstrates numerically that we are having a larger impact than any other species, worldwide,” said Belant.

Despite exact numbers not being the focal point of the study, Belant says the percentage of human-impacted deaths would have been even higher had indirect effects counted as human impact.

“Because we are only looking at direct human-caused mortality not indirect,” Belant said. “For example, alteration of habitat or land use change could and has been demonstrated to result in increased vulnerability of some species to predation risk.”

Travis DeVault, the second advisor on the study, agrees with Belant.

“It could be that humans are actually having a bigger influence on some of these groups then what this data shows,” said DeVault.

Devault used the example of feral cats. Despite being introduced by humans, when a feral cat killed an animal in the study it was marked as predation or a natural cause rather than a human cause.

While the information in this study is new, the value of this research is where it leads next. The study totals to more than 120,000 vertebrates and can be used to answer more specific questions about human impact on the planet.

Postdoctoral researcher at ESF, Jacob Hill is using the data he found in the study to explore the impact that government protected land has on the death rate of vertebrates. He wants to see the difference in death rates when vertebrates are on private land with no protection as opposed to government land with limitations on human impact.

“We’re just seeing whether or not in given an area if protected area status influences whether or [not] the amount of mortality that occurs.”

While he is unsure if he will explore further, Hill says he is able to use the data to narrow his focus to specific species.

For DeVault, the next step is specificity.

“I think there’s a lot of detail left in the data set that can be analyzed,” DeVault said. “It’s possible to dive deeper into specific mortality factors for certain groups of animals. So yeah, I think we have some work ahead of us.”

This study was able to give a big picture look at how humans impact the planet, but rather than be set in stone, the data is being added to.

“Wildlife researchers have been doing radio telemetry studies for decades but there hasn’t been a real wide-ranging synthesis of this data and I think this study is just the beginning. The data sets that we have now can be used to address a variety of questions,” said DeVault.

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