Eastern Red-backed Salamanders successfully invaded Newfoundland, Canada—an island with no native amphibians—by eating a wider variety of prey than their native cousins and by feeding on invasive insects already present on the island. According to Gram Research analysis, invasive salamanders consumed about two-thirds of their diet from invasive prey species, allowing them to thrive without competing with native predators.
A new study reveals how Eastern Red-backed Salamanders successfully invaded Newfoundland, Canada—an island with no native amphibians. According to Gram Research analysis, these salamanders adapted by eating a wider variety of prey than their cousins back home, and they took advantage of other invasive insects already living on the island. By studying what these salamanders ate, researchers discovered that two-thirds of their diet came from invasive prey species. This research helps scientists understand how animals survive in new environments and how previous invasions can actually help new invaders succeed.
Key Statistics
A 2026 systematic review published in PLOS ONE found that invasive Eastern Red-backed Salamanders in Newfoundland consumed approximately two-thirds of their prey volume from invasive invertebrate species already established on the island.
Research examining invasive salamander populations in Newfoundland showed that these salamanders maintained a significantly broader dietary niche compared to conspecifics in their native range, consuming a greater variety of prey types.
The 2026 study demonstrated that prior invasions of diverse invertebrate communities to Newfoundland bolstered the invasive potential of the Eastern Red-backed Salamander, supporting the Invasional Meltdown Hypothesis.
The Quick Take
- What they studied: How did Eastern Red-backed Salamanders successfully move to and survive in Newfoundland, Canada, where no salamanders lived before?
- Who participated: Researchers examined stomach contents from invasive salamanders living in Newfoundland and compared their diet to salamanders from their original home range using published studies.
- Key finding: Invasive salamanders in Newfoundland ate a much wider variety of prey than salamanders in their native range, and about two-thirds of what they ate were invasive insects that had already moved to the island.
- What it means for you: This research shows that invasive species can succeed by being flexible eaters and by taking advantage of other invasive species already present. Understanding this helps scientists predict which animals might become invasive and how to manage ecosystems.
The Research Details
Researchers used two main approaches to understand the salamanders’ success. First, they examined the stomachs of Eastern Red-backed Salamanders living in Newfoundland to see exactly what they were eating. Second, they searched through published scientific studies to find information about what these same salamanders eat in their native range in eastern North America. By comparing the two diets, they could see if the invasive population had changed its eating habits. They also classified each prey item as either native to Newfoundland or invasive (brought there by human activity).
This approach is called a systematic review because it combines new data collection with a careful review of existing published research. The researchers were testing two important scientific ideas: the Niche Breadth Invasion Hypothesis (the idea that invaders succeed by eating more types of food) and the Invasional Meltdown Hypothesis (the idea that previous invasions help new invasions succeed).
The study took place on the island of Newfoundland, Canada, which is unique because it had no native amphibians before humans arrived. This makes it a natural experiment for understanding how new species establish themselves.
This research approach is important because it reveals the actual mechanisms—the real reasons—why some invasive species succeed while others fail. Rather than just observing that salamanders invaded Newfoundland, the researchers identified the specific advantages these salamanders gained. Understanding these advantages helps scientists predict future invasions and develop better strategies to prevent harmful invasive species from establishing themselves.
The study combines direct observation (examining actual stomach contents) with a systematic review of existing literature, which strengthens the findings. However, the research doesn’t specify the exact number of salamanders examined, which would help readers understand how representative the results are. The study was published in PLOS ONE, a peer-reviewed scientific journal, which means other experts reviewed the work before publication. The comparison to native-range populations relies on published studies, so the quality depends on what information was available in the scientific literature.
What the Results Show
The most striking finding was that invasive salamanders in Newfoundland ate a much broader variety of prey than salamanders in their native range. This dietary flexibility appears to be a key advantage that helped them survive in a new environment. The researchers found that invasive salamanders weren’t picky eaters—they consumed whatever prey was available, rather than specializing in just a few types of food.
Even more interesting, about two-thirds of the prey volume that invasive salamanders ate came from invasive invertebrate species (insects, spiders, and other small creatures) that had already established themselves on the island. This means the salamanders were essentially feeding on a pre-made food supply created by previous invasions. The salamanders didn’t have to compete with native predators for native prey because there were no native amphibians on the island.
These findings support both scientific hypotheses the researchers were testing. The Niche Breadth Invasion Hypothesis was confirmed because the salamanders’ broader diet helped them avoid starvation in a new environment. The Invasional Meltdown Hypothesis was also supported because the presence of other invasive species actually helped the salamanders succeed.
The research also highlights an important ecological principle: invasive species don’t exist in isolation. The success of the invasive salamander population was directly tied to the earlier invasion of diverse invertebrate species. This suggests that ecosystems that have already been altered by multiple invasions may be more vulnerable to additional invasions. The study also demonstrates that Newfoundland’s lack of native amphibians meant there was no established predator-prey relationship to resist the salamander invasion.
This research builds on existing scientific understanding of how invasive species succeed. Previous studies have suggested that dietary flexibility is important for invasion success, but this is one of the first studies to directly compare the diets of invasive and native populations of the same species. The findings align with broader ecological theory about invasional meltdown—the idea that multiple invasions can reinforce each other. The study also contributes to understanding why island ecosystems, which often lack native predators and competitors, are particularly vulnerable to invasive species.
The study doesn’t specify exactly how many salamanders were examined, which makes it difficult to assess how representative the findings are. The comparison to native-range populations depends on information published in other studies, so gaps in that literature could affect the conclusions. The research focuses on one invasive species in one location, so the findings may not apply to other invasive amphibians or other ecosystems. Additionally, the study examines what the salamanders ate at one point in time, so it doesn’t show whether their diet has changed over the years since they invaded.
The Bottom Line
This research doesn’t provide direct health or lifestyle recommendations for people. Instead, it offers insights for environmental managers and conservation professionals: (1) Monitor islands and isolated ecosystems closely for invasive species, as they may be particularly vulnerable to invasion; (2) Recognize that controlling one invasive species may be insufficient if other invasive species are already present; (3) Prioritize preventing the initial invasion of diverse invasive species, as they may facilitate future invasions. Confidence level: Moderate to High, based on the systematic review approach and alignment with established ecological theory.
Environmental scientists, conservation managers, and policymakers should pay attention to this research, particularly those working with island ecosystems or managing invasive species. Educators can use this as a case study for teaching about ecology and invasive species. The general public should understand that invasive species problems are often interconnected—controlling one invasive species may require managing others.
This research describes processes that have already occurred over years or decades. The salamanders have already established themselves in Newfoundland, and the dietary patterns described are current. For future prevention efforts, the timeline would depend on early detection and rapid response to new invasions.
Frequently Asked Questions
How did salamanders invade an island that had no native amphibians?
Eastern Red-backed Salamanders likely arrived through human activity (possibly in transported materials) and survived by eating a wider variety of prey than their native cousins, including invasive insects already on the island. This dietary flexibility prevented starvation in their new environment.
What do invasive salamanders eat compared to native ones?
Invasive salamanders in Newfoundland eat a much broader variety of prey than salamanders in their native range. Approximately two-thirds of their diet consists of invasive invertebrate species, showing they’re flexible eaters that exploit available food sources.
Can one invasive species help another invasive species succeed?
Yes. This research demonstrates that previous invasions of diverse invertebrate species to Newfoundland created a food supply that helped the invasive salamander population establish itself. This phenomenon is called invasional meltdown.
Why are island ecosystems more vulnerable to invasive species?
Islands like Newfoundland lack native predators and competitors that would normally resist invasions. The salamanders faced no native amphibian competition, and they could feed on invasive prey with no natural enemies to control their population.
What does this research mean for preventing future invasions?
The study suggests that controlling multiple invasive species is more important than controlling just one. Preventing the initial invasion of diverse invasive species may be the best strategy to stop future invasions from succeeding.
Want to Apply This Research?
- If using an environmental monitoring app, users could track sightings of Eastern Red-backed Salamanders and invasive invertebrate species in their region, noting the location, date, and any observations about prey availability. This crowdsourced data could help scientists monitor invasive species spread.
- Users interested in conservation could use an app to report invasive species sightings to local environmental agencies, helping authorities respond quickly to new invasions. Users could also track native species in their area to understand local biodiversity and identify changes over time.
- Long-term monitoring could involve regular surveys of specific locations to track whether invasive salamander populations are expanding, whether invasive prey species are increasing, and how native species are responding. Apps could enable citizen scientists to contribute standardized observations over months and years.
This research describes ecological and biological processes related to invasive species. It does not provide medical advice. The findings are specific to Eastern Red-backed Salamanders in Newfoundland and may not apply to other species or ecosystems. Anyone concerned about invasive species in their area should contact local environmental agencies or wildlife management authorities. This article is for educational purposes and should not be used as the sole basis for environmental management decisions.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.