Within Radar
Can Birds and Bugs Look Like UFOs on Radar?
Birds, insects, rain, and ice can all create real radar returns that are easy to mistake for aircraft when context is missing.
On this page
- Why biological targets appear on radar
- Weather returns that can mimic aircraft movement
- Clues that separate aircraft from clutter
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Introduction
Yes. Birds, insects, rain, snow and ice can all produce genuine radar echoes that may be mistaken for aircraft when operators lack supporting information. Radar does not identify objects directly; it detects reflected radio energy. Anything that reflects enough energy back to the antenna can appear as a target. In aviation and military surveillance, these unwanted or ambiguous returns are known as biological or weather clutter. In some UFO reports, a radar contact may therefore represent a real phenomenon in the atmosphere without representing a conventional aircraft or an unknown craft. Understanding how bio-clutter appears is essential when evaluating radar-based UFO claims. [Weather.gov]weather.govUsing and Understanding Doppler RadarThe radar emits a burst of energy (green in the animated image). If the energy strikes an object (ra…
Can Birds and Bugs Look Like UFOs on Radar?
Birds and insects are not merely theoretical sources of radar interference. Modern weather-radar networks routinely detect them so clearly that entire scientific fields have developed around analysing these signals. Researchers use weather radar to track bird migration, bat movements and large-scale insect activity because the echoes are strong enough to be measured across vast areas. [BirdCast]birdcast.orgBirdCastRadar OrnithologyWe turn weather radar data into information describing the numbers and flight directions, speeds and altitudes o… BirdCast The reason is simple: radar measures reflected energy [birdcast.org]birdcast.orgBirdCastRadar OrnithologyWe turn weather radar data into information describing the numbers and flight directions, speeds and altitudes o…, not biological identity. A single bird usually creates only a small return, but thousands of birds flying together can generate a radar signature comparable to a much larger object. Large insect swarms can do the same, especially when concentrated in dense layers of warm air. Weather radars are sensitive enough that even individual bugs, birds and bats can contribute to detectable returns. [NOAA Institutional Repository]repository.library.noaa.govInstitutional RepositoryA Machine Learning Approach for Classifying Bird and…by P Jatau · 2021 · Cited by 44 — A machine learning appr…
Historically, radar operators encountered this problem almost immediately after radar entered widespread use. During the Second World War, unexplained radar echoes produced by birds and insects were sometimes called “angels” before their biological origin became better understood. Modern meteorological systems still devote significant effort to separating biological targets from weather and aircraft returns. [The Guardian]theguardian.comConducted between 2014 and 2021, the research repurposed data from 15 weather surveillance radars to monitor aerial insect activity, with…
Why biological targets appear on radar
Several characteristics make biological targets visible:
- Large numbers compensate for small size. A flock containing thousands of birds can create a substantial radar echo. [Lincoln Laboratory]ll.mit.eduLincoln Laboratory Radar Clutter and ChaffLincoln LaboratoryRadar Clutter and ChaffAugust 1, 2008 — Since birds move at relatively low velocities, their speed, if measured, can be…
- Migration occurs at aircraft-relevant altitudes. Migrating birds may travel hundreds or thousands of metres above the ground, placing them in the same volume of air monitored by surveillance radars. [BirdCast]birdcast.orgBirdCastRadar OrnithologyWe turn weather radar data into information describing the numbers and flight directions, speeds and altitudes o…
- Insects can form dense aerial layers. Weather radars regularly observe huge concentrations of insects carried by winds. [The Weather Channel]weather.comSuch was the case Wednesday morning in the Midwest.Read moreThe Weather ChannelBugs Show Up on Radar in the MidwestMay 16, 2019 — Although radar is typically used for tracking rain and snow, it can… [FOX Weather]foxweather.comFOX WeatherProject tracks bird migration using NWS Doppler RadarMay 14, 2022 — Using algorithms over years of research, scientists can de…
- Biological movement creates coherent tracks. A flock moving steadily can appear as a legitimate moving target rather than random noise. [KNMI]cdn.knmi.nlKNMIBird detection by operational weather radarThe bird radar allows to verify the targets as birds by analyzing the wing beat pattern or…
These factors mean that a radar operator observing an isolated return without visual confirmation may initially see something that resembles an aircraft track.
How Weather Creates Aircraft-Like Returns
Weather is among the most common sources of radar echoes because precipitation is specifically designed to be detected by radar. Rain, snow, hail and ice crystals all scatter radio energy back toward the receiver. [Weather.gov]weather.govOpen source on weather.gov.
In favourable conditions, weather returns can create patterns that appear surprisingly structured. Radar displays may show compact cells, elongated bands, expanding rings or moving patches. If an observer focuses only on motion rather than meteorological context, these returns can appear to represent discrete airborne objects. [Radartutorial]radartutorial.euRadartutorialWeather Radar ClutterThis page provides an overview of some of the techniques that are commonly used to eliminate clutter an…
Weather-related ambiguity increases when:
- Storm cells move rapidly across the display.
- Wind shear causes complex velocity signatures.
- Ice crystals create unusual reflectivity patterns.
- Small weather features appear isolated from larger storm systems.
Modern weather radars are highly sensitive and frequently detect phenomena beyond ordinary rain and snow. Radar systems have recorded butterflies, birds trapped within storms, meteor fragments and aircraft-generated atmospheric effects. Such examples demonstrate how diverse radar targets can be. [The Washington Post]washingtonpost.comThe Washington Post Is that a meteor or a flock of birds?Things you can catch on radar.February 23, 2025 — Weather radar systems operated by the National Weather Service are primarily designed t…
A memorable example: roost rings
One of the clearest demonstrations of biological radar clutter is the “roost ring”. Shortly before sunrise, thousands of birds leaving a communal roost create an expanding circular pattern on Doppler weather radar. To an untrained observer, the expanding ring could appear highly unusual. To radar ornithologists, however, it is a recognised biological signature produced by birds dispersing from a central location. [Weather.gov]weather.comSuch was the case Wednesday morning in the Midwest.Read moreThe Weather ChannelBugs Show Up on Radar in the MidwestMay 16, 2019 — Although radar is typically used for tracking rain and snow, it can…
The existence of such distinctive patterns shows that radar can display dramatic moving targets generated entirely by wildlife rather than aircraft. [Weather.gov]weather.govWIND FARM INTERACTION WITH NEXRAD RADARIn fact, wind turbine clutter appears on the radar much like numerous other non-meteorological obj…
Why Clutter Sometimes Produces UFO Reports
A radar contact can appear impressive because it seems objective and instrument-based. Yet radar operators often work with incomplete information. A brief return may appear before weather data, visual observations or identification algorithms are consulted.
Several factors can make clutter appear more mysterious than it is:
- The target may be detected only briefly.
- No visual confirmation may exist.
- The return may appear in an unexpected location.
- The radar system may provide position but not identity.
- Software may initially track clutter as though it were a genuine moving object. [SkyRadar]skyradar.comSkyRadarATSEP Use Cases: Impact of False Targets on Air Traffic Control21 Sept 2023 — Clutter refers to false targets generated by radar…
Bird flocks can be particularly confusing because they sometimes move cohesively and generate trackable radar signatures. Modern studies of airport surveillance and drone detection continue to identify bird-versus-aircraft or bird-versus-drone discrimination as a significant technical challenge. [MDPI]mdpi.com2504 446XMDPIAirport Ground-Based Aerial Object Surveillance…by J Samu · 2025 — A recurring difficulty is distinguishing between birds and UAS…
Clues That Separate Aircraft from Clutter
Radar operators and researchers have developed many techniques for distinguishing aircraft from biological and weather targets.
Movement relative to the wind
One of the strongest clues is whether the target follows atmospheric motion.
Large insect concentrations often drift with prevailing winds. Birds, by contrast, can maintain headings independent of the wind. Aircraft usually exhibit even more deliberate and consistent navigation behaviour. Comparing target motion with weather and wind data often helps identify the source. [FOX Weather]foxweather.comFOX WeatherProject tracks bird migration using NWS Doppler RadarMay 14, 2022 — Using algorithms over years of research, scientists can de…
Shape and distribution
Biological targets often appear as diffuse clouds, rings or broad regions rather than isolated point targets. Weather returns likewise tend to form larger structures. Aircraft generally generate more compact and persistent tracks. [Weather.gov]weather.govNational Weather ServiceIsolated Severe Thunderstorms and Critical Fire Weather Tuesday · Freeze Warning · Red Flag Warning · Heat Adviso…
Time of day and season
Many biological echoes follow predictable patterns:
- Bird migration peaks during specific seasons.
- Roost departures occur around dawn. [weather.gov]weather.govSource details in endnotes.
- Insect activity increases under favourable temperature conditions.
- Bat emergence occurs at characteristic evening periods. Weather.gov+2Inside NSSL [inside.nssl.noaa.gov]inside.nssl.noaa.govnssl uses weather radar clutter to help biologistsInside NSSLNSSL uses weather radar clutter to help biologistsMar 2, 2011 — The radar images of bats appear as distinct “blooms.” Usually…
A radar contact that coincides with these patterns is less likely to represent an unidentified craft.
Advanced radar classification
Modern Doppler and dual-polarisation radars analyse more than simple position. Researchers now use machine-learning systems and polarimetric measurements to distinguish birds, insects and precipitation from one another. These techniques exist precisely because biological and weather clutter are common and significant radar targets. [NOAA Institutional Repository]repository.library.noaa.govInstitutional RepositoryA Machine Learning Approach for Classifying Bird and…by P Jatau · 2021 · Cited by 44 — A machine learning appr…
What This Means for Radar-Based UFO Reports
Radar clutter from birds, insects and weather does not mean every radar-associated UFO report is explained. It does mean that a radar return alone is not sufficient evidence that an unknown craft was present. Biological scatter and weather echoes are well-documented, routinely observed and sometimes dramatic enough to resemble meaningful targets on radar displays. Investigators therefore treat weather records, migration data, wind conditions and radar-processing details as essential context before concluding that a radar contact represents anything unusual. [SkyRadar]skyradar.comSkyRadarATSEP Use Cases: Impact of False Targets on Air Traffic Control21 Sept 2023 — Clutter refers to false targets generated by radar… [BirdCast]birdcast.orgBirdCastRadar OrnithologyWe turn weather radar data into information describing the numbers and flight directions, speeds and altitudes o…
Amazon book picks
Further Reading
Books and field guides related to Can Birds and Bugs Look Like UFOs on Radar?. Use these as the next step if you want deeper reading beyond the article.
Introduction to Radar Systems
Provides the foundation for understanding biological and weather clutter.
Weather radar technology beyond NEXRAD
First published 2002. Subjects: Evaluation, Meteorological services, Radar meteorology, Technological innovations, Weather forcasting.
Living on the Wind
First published 1999. Subjects: Birds, Migration, Birds, migration, Migratory birds.
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Endnotes
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Source: weather.gov
Link: https://www.weather.gov/mkx/using-radarSource snippet
Using and Understanding Doppler RadarThe radar emits a burst of energy (green in the animated image). If the energy strikes an object (ra...
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Source: skyradar.com
Link: https://www.skyradar.com/blog/atsep-use-cases-impact-of-false-targets-on-air-traffic-controlSource snippet
SkyRadarATSEP Use Cases: Impact of False Targets on Air Traffic Control21 Sept 2023 — Clutter refers to false targets generated by radar...
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Source: birdcast.org
Link: https://birdcast.org/radar-technology/Source snippet
BirdCastRadar OrnithologyWe turn weather radar data into information describing the numbers and flight directions, speeds and altitudes o...
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Source: birdcast.org
Link: https://birdcast.org/a-primer-for-using-weather-surveillance-radar-to-study-bird-migration/Source snippet
A primer for using weather surveillance radar to study bird...Using meteorologists' “discarded” data, we meticulously attempt to charact...
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Source: inside.nssl.noaa.gov
Title: nssl uses weather radar clutter to help biologists
Link: https://inside.nssl.noaa.gov/nsslnews/2011/03/nssl-uses-weather-radar-clutter-to-help-biologists/Source snippet
Inside NSSLNSSL uses weather radar clutter to help biologistsMar 2, 2011 — The radar images of bats appear as distinct “blooms.” Usually...
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Source: repository.library.noaa.gov
Link: https://repository.library.noaa.gov/view/noaa/34122Source snippet
Institutional RepositoryA Machine Learning Approach for Classifying Bird and...by P Jatau · 2021 · Cited by 44 — A machine learning appr...
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Source: repository.library.noaa.gov
Title: noaa 61003 DS1
Link: https://repository.library.noaa.gov/view/noaa/61003/noaa_61003_DS1.pdfSource snippet
NOAA Institutional RepositoryInsects as radar targets: size, form, density and permittivityby V Alistair Drake · 2024 · Cited by 6 — To m...
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Source: weather.gov
Link: https://www.weather.gov/iln/birds -
Source: weather.com
Title: Such was the case Wednesday morning in the Midwest.Read more
Link: https://weather.com/science/weather-explainers/news/2019-05-16-radar-bugs-bats-sunriseSource snippet
The Weather ChannelBugs Show Up on Radar in the MidwestMay 16, 2019 — Although radar is typically used for tracking rain and snow, it can...
Published: May 16, 2019
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Source: cdn.knmi.nl
Link: https://cdn.knmi.nl/knmi/pdf/bibliotheek/knmipubWR/WR2009-06.pdfSource snippet
KNMIBird detection by operational weather radarThe bird radar allows to verify the targets as birds by analyzing the wing beat pattern or...
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Source: radartutorial.eu
Link: https://www.radartutorial.eu/15.weather/wr22.en.htmlSource snippet
RadartutorialWeather Radar ClutterThis page provides an overview of some of the techniques that are commonly used to eliminate clutter an...
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Source: mdpi.com
Title: 2504 446X
Link: https://www.mdpi.com/2504-446X/10/1/22Source snippet
MDPIAirport Ground-Based Aerial Object Surveillance...by J Samu · 2025 — A recurring difficulty is distinguishing between birds and UAS...
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Source: nssl.noaa.gov
Link: https://www.nssl.noaa.gov/publications/wsr88d_reports/Bird_detection_algorithm_2019.pdfSource snippet
detection algorithmby P Jatau — Migration direction changes with wind, [range]({{ 'range/' | relative_url }}) (height) from the radar, time of day and weather. This coupl...
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Source: repository.library.noaa.gov
Title: noaa 32181 DS1
Link: https://repository.library.noaa.gov/view/noaa/32181/noaa_32181_DS1.pdfSource snippet
noaa.govDual- polarization radar products for biological applicationsby PM Stepanian · 2016 · Cited by 150 — The application and interpre...
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Source: weather.gov
Link: https://www.weather.gov/roc/WindFarmsSource snippet
WIND FARM INTERACTION WITH NEXRAD RADARIn fact, wind turbine clutter appears on the radar much like numerous other non-meteorological obj...
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Source: weather.gov
Link: https://www.weather.gov/Source snippet
National Weather ServiceIsolated Severe Thunderstorms and Critical Fire Weather Tuesday · Freeze Warning · Red Flag Warning · Heat Adviso...
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Source: weather.gov
Link: https://www.weather.gov/mlb/Doppler_Dual_Pol_Weather_RadarSource snippet
NWS Weather RadarThe entire goal of the weather radar equation is to take the power returned from weather objects, and convert that value...
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Source: weather.gov
Link: https://www.weather.gov/bgm/researchRadarandBirds1997Source snippet
the WSR-88D Doppler Radar at WFO Binghamton, NYThe radar data provides a very good idea of where the birds roost and when they become act...
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Source: wildlife.org
Link: https://wildlife.org/wsb-airports-avian-radar-spots-just-15-percent-of-birds/Source snippet
WSB: Airport's avian radar spots just 15 percent of birdsOct 3, 2018 — WSB: Airport's avian radar spots just 15 percent of birds...
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Source: birdcast.org
Link: https://birdcast.org/weather-surveillance-radar-beyond-meteorology/Source snippet
A 24-hour national mosaic animation of radar imagery featuring large numbers of birds taking flight.Read more...
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Source: mdpi.com
Link: https://www.mdpi.com/2673-4931/8/1/48Source snippet
Detecting Birds and Insects in the Atmosphere Using...by P Jatau · 2021 · Cited by 12 — NEXRAD radars detect biological scatterers in th...
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Source: radartutorial.eu
Title: Weather is not clutter in a weather detecting radar.Read more
Link: https://www.radartutorial.eu/11.coherent/co04.en.htmlSource snippet
The basic types of clutter - RadartutorialClutter is the term used and includes ground returns, sea returns, weather, buildings, birds an...
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Source: theguardian.com
Link: https://www.theguardian.com/environment/2025/oct/27/night-flying-insects-over-uk-in-decline-weather-radar-study-revealsSource snippet
Conducted between 2014 and 2021, the research repurposed data from 15 weather surveillance radars to monitor aerial insect activity, with...
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Source: ll.mit.edu
Title: Lincoln Laboratory Radar Clutter and Chaff
Link: https://www.ll.mit.edu/sites/default/files/outreach/doc/2018-07/lecture%207.pdfSource snippet
Lincoln LaboratoryRadar Clutter and ChaffAugust 1, 2008 — Since birds move at relatively low velocities, their speed, if measured, can be...
Published: August 1, 2008
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Source: foxweather.com
Link: https://www.foxweather.com/learn/birds-project-tracks-bird-migration-using-nws-doppler-radarSource snippet
FOX WeatherProject tracks bird migration using NWS Doppler RadarMay 14, 2022 — Using algorithms over years of research, scientists can de...
Published: May 14, 2022
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Source: washingtonpost.com
Title: The Washington Post Is that a meteor or a flock of birds?
Link: https://www.washingtonpost.com/weather/2025/02/23/weather-radar-butterflies-planes-doppler/Source snippet
Things you can catch on radar.February 23, 2025 — Weather radar systems operated by the National Weather Service are primarily designed t...
Published: February 23, 2025
-
Source: facebook.com
Link: https://www.facebook.com/NOAA/Source snippet
National Oceanic and Atmospheric Administration (NOAA)National Oceanic and Atmospheric Administration (NOAA), Washington D. C. 730620 lik...
-
Source: radarscope.zendesk.com
Link: https://radarscope.zendesk.com/hc/en-us/articles/4416722636946-Biological-Scatter-What-You-Can-See-On-Radar-Other-Than-RainSource snippet
Scatter - What You Can See On Radar Other Than...Jan 19, 2023 — We will look at several examples of biological scatter, including birds...
Additional References
-
Source: facebook.com
Link: https://www.facebook.com/ericsnitilwx/posts/hey-whats-that-theres-all-sorts-of-stuff-showing-up-on-radar-tonight-yet-its-not/1313906850101710/Source snippet
HEY, WHAT'S THAT? There's all sorts of "stuff" showing up on...On radar, we can tell they're birds because the objects have “low correla...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/282366086_Aviation_Bird_Hazard_in_NEXRAD_Dual_Polarization_Weather_Radar_Confirmed_by_Visual_ObservationsSource snippet
(PDF) Aviation Bird Hazard in NEXRAD Dual Polarization...Dec 18, 2025 — The conventional approach to detecting animals in weather radar...
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Source: detect-inc.com
Link: https://detect-inc.com/aircraft-birdstrike-avoidance-radar/ -
Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC2607429/Source snippet
identification of bird targets with radar via patterns...by S Zaugg · 2008 · Cited by 156 — In a study on bird migration, radar signals...
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Source: youtube.com
Link: https://www.youtube.com/user/FAAnewsSource snippet
Federal Aviation AdministrationWelcome to the official YouTube channel of the Federal Aviation Administration (FAA). Our mission is simpl...
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Source: youtube.com
Link: https://www.youtube.com/noaaSource snippet
noaaThe National Oceanic and Atmospheric 's (@NOAA) mission is to understand and predict changes in the Earth's environment, from the dep...
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Source: animalmigration.org
Link: https://www.animalmigration.org/aeroecology/index.htmSource snippet
Radar Aeroecology - Animal Migration Research GroupThis radar is used to forecast our weather, but also detects birds, bats and bugs...
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Source: facebook.com
Title: Federal Aviation Administration | Washington D.C
Link: https://www.facebook.com/FAA/Source snippet
DCFederal Aviation Administration . Our continuing mission is to provide the safest, most efficient aerospace system in the world. Gov...
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Source: Wikipedia
Title: National Oceanic and Atmospheric Administration
Link: https://de.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_AdministrationSource snippet
National Oceanic and Atmospheric AdministrationDie National Oceanic and Atmospheric Administration (NOAA; Nationale Ozean- und Atmosph...
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Source: Wikipedia
Title: National Oceanic and Atmospheric Administration
Link: https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_AdministrationSource snippet
National Oceanic and Atmospheric AdministrationThe National Oceanic and Atmospheric Administration (NOAA /ˈnoʊ.ə/ NOH-ə) is a United S...
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