Concept · environmental-science
Invasive species
Follow Invasive species — see important new research and changes in evidence.Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Rewordings are not listed.
- Concept page published
Invasive-species research measures how non-native organisms spread or how suppression at landscape scale changes their numbers.
It is a conservation management question: control, not just a species list.
Evidence
What the evidence shows
Drawn from 3 studies in this library. Each finding starts with a plain-language takeaway, then the denser detail. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope with a short note on each study’s contribution. Challenged positions are labeled — they are not findings.
This library holds 3 empirical papers on invasive species with measured outcomes rather than reviews.
- Barred owls and megafire hit native owls differently
- Rat-free islands could rebuild seabirds and reefs
- Suppressing invasive brown trout networks
Study Role Design N Population Outcome Barred owls and megafire hit native owls differently Supports OtherPassive acoustic occupancy modeling across megafires and barred owl removal experiment N=265 · 265 hexagonal survey cells with 517 ARUs; 80 barred owl/hybrid removals Owls across >6,000 km² of the northern Sierra Nevada Site occupancy of flammulated, pygmy, and great horned owls after fire and removals Rat-free islands could rebuild seabirds and reefs Supports Computational / modellingHabitat/abundance models predicting Chagos seabird recovery and reef-fish biomass under rat eradication N=25 · Modeled eradication on 25 rat-infested islands (scenario study, not a field trial N) Lesser noddies, sooty terns, and red-footed boobies on Chagos Archipelago islands Predicted seabird abundance, nitrogen deposition, and reef-fish biomass under restoration Suppressing invasive brown trout networks Supports Computational / modellingMetapopulation PVA of invasive brown trout under removal and climate/reservoir scenarios Simulation scenarios (18 under current climate); not an empirical sample-size study Modeled brown trout in Colorado River and Bright Angel Creek subpopulations Time and probability of quasi-extinction under multi-life-stage suppression Flammulated owls declined 71% in severe burns and doubled after barred owl removals; pygmy and great horned owls barely budged.
Eradicating invasive rats and restoring native vegetation on Chagos islands could multiply seabirds ~18-fold and raise reef-fish biomass via seabird-derived nitrogen.
Only metapopulation-wide, multi-life-stage suppression quickly drove invasive brown trout toward quasi-extinction.
Open questions
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes — limits on how far one study travels — not a forced fight between papers.
A metapopulation model or a local suppression trial does not generalise to every invader.
- Barred owls and megafire hit native owls differently
- Rat-free islands could rebuild seabirds and reefs
Study Role Design N Population Outcome Barred owls and megafire hit native owls differently Supports OtherPassive acoustic occupancy modeling across megafires and barred owl removal experiment N=265 · 265 hexagonal survey cells with 517 ARUs; 80 barred owl/hybrid removals Owls across >6,000 km² of the northern Sierra Nevada Site occupancy of flammulated, pygmy, and great horned owls after fire and removals Rat-free islands could rebuild seabirds and reefs Supports Computational / modellingHabitat/abundance models predicting Chagos seabird recovery and reef-fish biomass under rat eradication N=25 · Modeled eradication on 25 rat-infested islands (scenario study, not a field trial N) Lesser noddies, sooty terns, and red-footed boobies on Chagos Archipelago islands Predicted seabird abundance, nitrogen deposition, and reef-fish biomass under restoration
Common misconceptions
Eradication is always cheaper than living with the species.
Control costs, reinvasion and non-target effects depend on the system.
Exam-style questions
Short-answer questions that ask you to explain or compare, not recall.
What does invasive species mean in this library?
Invasive-species research measures how non-native organisms spread or how suppression at landscape scale changes their numbers.
Name one empirical finding from the invasive species papers.
Flammulated owls declined 71% in severe burns and doubled after barred owl removals; pygmy and great horned owls barely budged.
What is a limit of invasive species evidence here?
A metapopulation model or a local suppression trial does not generalise to every invader.
The studies
3 studies in this library bear on Invasive species, ordered by citations.
- Rat-free islands could rebuild seabirds and reefs
Eradicating invasive rats and restoring native vegetation on Chagos islands could multiply seabirds ~18-fold and raise reef-fish biomass via seabird-derived nitrogen.
- Suppressing invasive brown trout networks
Only metapopulation-wide, multi-life-stage suppression quickly drove invasive brown trout toward quasi-extinction.
- Barred owls and megafire hit native owls differently
Flammulated owls declined 71% in severe burns and doubled after barred owl removals; pygmy and great horned owls barely budged.
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