Effects of Fireworks on Birds – A critical Overview
Stickroth, H. (2015): Auswirkungen von Feuerwerken auf Vögel – ein Überblick. -
Berichte zum Vogelschutz 52: 115–149. PDF-Download
A critical overview of the effects of fireworks is provided based on observations of 133
fireworks with 272 documented species-reactions. The occasion for this study arose from
individual observations which hinted at such effects, but whose meaning nevertheless
could not be assessed due to the lack of a general overview. The observations were
compiled using internet and database research as well as surveys among birdwatchers.
These were then subjected to critical evaluation in order to determine the likelihood that
such effects were the result of fireworks.
70% of the observations came from Germany (primarily chance observations), 18% from
the United States of America (to a high extent from planned observation and monitoring)
and the remainder came from the Netherlands, Switzerland, Austria and a few other
countries. In the portion from Germany, observations came from almost all of the German
states – though the southern states of Germany are somewhat underrepresented.
The observations are divided among 88 taxa (species or higher taxa) from different
taxonomic or ecological groups (waterbirds s.s., cormorants, geese, Lari families, big
wading birds, birds of prey, owls, gamebirds, oscine families and woodpeckers, crows and
pigeons). The three most prominent species were the greylag goose, the white stork and
the common crane.
Traditionally, fireworks are lit to celebrate the new year, national holidays or large events –
though there is an increase in private use (including association celebrations) or for
commercial purposes. National firework traditions also vary greatly. In Germany, the legal
basis for fireworks is regulated by the “Erste Verordnung zum Sprengstoffgesetz” (1.
SprengV, First Ordinance to the Explosives Act).
Disturbance - stimuli and general effects
Lighting fireworks in the environment of wildlife represents a human-caused disturbance
stimulus, which – depending on the type of firework, exposure, distance and time of year
as well as the species-specific and individual sensitivities of the exposed species – can
have varying disturbance effects. Birds react to the visual stimuli (flash and light “storms”)
as well as to the acoustic stimuli (muffled to loud bangs, shrill whistling sounds, etc.) of
For some reactions, visual stimuli played only a minor role, particularly at greater
distances when noise from the fireworks could barely be heard. However, even at shorter
distances, a primarily visual stimulus (for example, signal rocket) can cause reactions up
to physical flight. The main effect here though is the surprise effect caused by the sudden
flash and light “storm”, which is different than a meteorological storm that birds can detect
beforehand due to its slow approach and the drop in air pressure.
Unlike continuous noise, which birds often get habituated to, the acoustic stimuli of
fireworks often produced strong reactions and even panic. In 21 cases, the disturbances
were primarily acoustic in nature (compared to 4 cases in which the disturbances were
primarily visual). This matches observations that sonic booms and other sudden noise
events often lead to startle reactions – though waterbirds apparently react more
sensitively than birds of prey and mammals. Strengthened reactions were also observed
during hunting season, so that one can assume – at least in part – that the birds associate
the disturbances with hunting.
The manner in which birds are disturbed by pulsating bass, sonic booms and deterrents
using pulse detonation technology make it very likely that birds perceive even the
pressure waves from firework explosions as a disturbance stimulus and find this
unpleasant and perhaps even painful. This perception may occur via the paratympanic
organ in the inner ear or via the air sacs. Habituation to the pulse detonation technology
apparently does not occur– which matches the observation of no habituation to fireworks.
Disturbance stimuli must cross a stimulus threshold before they lead to a reaction. The
stimulus threshold is species-specific (e.g. physiology, ecology, adaptation to predation,
etc.) and individually determined (e.g. learning through experience, habituation, etc.), thus
leading to more tempered or heightened reactions. However, it seems to be questionable,
whether the stimuli created by fireworks represent adequate disturbance stimuli sufficient
for expedient biological reactions or whether these are not simply achieved as a result of
their high-threshold nature and surprise effect. The simultaneous appearance of various
types of stimulus from one and the same source of disturbances (summation) or of
identical types of stimulus from different sources (cumulation) have an increased negative
effect according to other authors.
A series of similar disturbance stimuli and an increase in the rate of disturbances led to
sensitizing and, thus, stronger disturbing effects. Repeated disturbances often led to
increased evasion and even to complete abandonment of the area. Typically, the
individual and species count sank.
The intensity of the disturbance stimulus determines if it crosses the stimulus threshold:
This essentially depends on the height, the volume, and the distance of the fireworks as
well as on their perceptibility at the place of disturbance. Shielding structures reduce the
strength of the reaction, while reflecting (buildings, dunes, hills, etc.) or sound-carrying
structures (water surface) increase it. The height and volume of the fireworks of course
depend on the type of fireworks. Large fireworks reach greater elevations, use larger
explosive charges, and thus achieve greater intensity as well as create greater
disturbance effects. On average, small fireworks or German New Year’s fireworks
(Silvesterfeuerwerke) had an effect about 5 times as far as firecrackers or bangers, while
large fireworks had an effect twice as far as small fireworks or German new year’s
It cannot be demonstrated with certainty that birds of prey are less susceptible to
disturbance than other birds. Single observations, however, seem to support this. Beyond
this, the disturbance effects from fireworks were significantly stronger in open country than
in the woods. It remained, however, unclear if this is due to the ecologically-determined
higher sensitivity of the species in open land or if the open land increases the intensity of
the disturbance. Birds that breed in colonies were more sensitive to disturbances during
breeding season than the other species studied. All species groups were less affected
during winter, presumably because they are in their energy-saving mode.
Direct damage, disturbance effects and consequential damage
Intentional or unintentional direct hits on birds by firework materials have only been
documented on rare occasion. Only in individual cases has it seemed sufficiently clear
that fireworks were the clear cause of the bird’s death or injury. Several case studies and
entries in internet discussion forums indicate that such occurrences take place more often
than usually thought. In particular, one must assume that intentional targeting with
fireworks occurs often. In individual cases, the killing or burning of the animal have been
proven. The incidence of hearing damage as result seems unlikely due to the special
anatomy of bird’s ears. There is no information concerning other damage due to explosion
pressure, eye damage or damage by residues of combustion.
Typically, a disturbance stimulus leads the bird to stop its behavior up to that point and
instead brings it to a state of vigilance or causes further disturbing effects. However, this is
not always an outward reaction. The few studies available on this topic prove
physiological reactions (e.g. increased heart rate, hormone release, and other metabolic
reactions) and that fireworks cause a stress for the bird, even if they show not a larger
reaction (bodily activity, flight, etc.). For partridges, just being woken up at night causes
them to use about 5% more of their energy. For a griffon vulture, the heart rate increases
from 50 to 170 beats per minute – something which ordinarily only occurs at maximum
For the simplest and weakest cases, outward signs of anxiety and fear involve changes in
body posture. There is ample proof of increased vigilance (noticing, protecting, etc.),
warning cries and contact calls (often emitted in flight), backward head motions, running
around, hopping back and forth nervously, sitting down or ducking, motions caused by
fear (wincing) and intentional movements. There are no case studies involving possible
further reactions such as shaking due to fear or displacement activities.
Flight was the most documented phenomenon, and, where possible, a distinction was
made between “normal flight” and panic. Due to lowered visibility at night, fleeing birds
were often only heard and species that do not call as much were not noticed. Flight
because of fireworks does also not only mean the animals flew away. Many species or
individuals fled by flying, running or swimming into protective bank vegetation or to areas
far off. This is particularly true for non-flying individual animals or young birds that have
not yet learned to fly. In extreme cases, these young birds jumped or fell out of the nest
(e.g. storks, heron). Flight also contains within it the danger of aftereffects, meaning that
the birds hurt or exhaust themselves; in particular, young birds that have not yet learned
to fly become easy prey for predators, have accidents or get lost completely.
The greatest danger comes from the aftereffects of a panic, which comprises a third of all
documented flights. Compared to other disturbance effects, flocking birds react more often
by taking flight and panicking than the remaining species groups, particularly geese and
cranes. After panics, the complete or partial count of birds then returned less often than
after “normal flight”, and the length of the absence and anxiety was longer. The
percentage reduction was on average longer, and 9 of the 10 documented fatalities were
attributable to panics. Wayward birds were found at distances of up to 15 km away.
Seagulls and crows, which are flocking birds too, tend to first fly upwards to gain a literal
overview of the situation without initially demonstrating full departure flight tendencies.
New Year’s Eve fireworks are an exception since they occur over a large area. In the
Netherlands during such fireworks, weather radar calculates peak density values of up to
100,000 cm2/km2. That corresponds to 666, 2000, and 9090 birds scared off per km2 in
the goose, duck, and small bird size categories, respectively. The birds also flew up to
greater heights (as much as 500 meters) than they flew during their normal daily flights.
Densely populated areas (in other words, where there are lots of fireworks) in some cases
were completely abandoned.
As a result of flight or panic, birds can become disoriented (due to poor visibility, night,
fog, etc.), fly into obstacles (buildings, power lines, trees, etc.) and injure themselves or
even die. Here, again, it is the flocking birds that are particularly at risk. Single cases have
been documented with up to 5,000 fatalities. There is also evidence of white storks being
injured or dying as a result of fireworks.
Reproductive success also may be reduced as a result of flight. There are case studies in
which the nest was given up or the adult birds returned to the nest so late that the
unprotected brood fell victim to weather conditions or predators. The brood can also be
damaged during flight, such as when eggs or young are unintentionally pushed out of the
nest or crushed in the nest. For cormorants, the loss of young was up to 30 times higher
and up to 83% of its total nest loss was determined to have occurred on the night of the
fireworks; for heron, the loss of young was much less pronounced. The mortality risk for
young birds also then increases when contact with the parental flock – within whose
structure the acquisition of food, social behavior and traditions (e.g. roosting sites during
migration) are taught – is lost during flight. Observations of these were made among
waterbirds and cranes.
Independent of these short-term effects, flight decreases the fitness of individual birds,
thus weakening them and making them more susceptible illness or parasites. Due to the
loss of time and habitat – that undoubtedly arise as a result of flight –, they also lose sleep
for recovering and time for feeding in order to regain energy. The scale of the forced
change of place becomes clear when examining those that return after flight or panic:
Only in 10% of cases (of 182) did the frightened birds completely return, in 59% of cases
they did so partially, and in 30% of cases they did not return at all. This inevitably leads to
a deterioration of the animal’s energy balance since flying (for geese) consumes about ten
times more energy than dietary intake and about twenty times more energy than the basal
metabolic rate; changes of location of up to 15 km were observed as were climbs to
higher than usual elevations. But the stress alone causes an increase in energy needs.
The additional energy expense was calculated into the needs for a day stage on a crane’s
flight towards France. In such times with high energy needs and a simultaneously poor
food supply situation, this can lead to an emergency situation that is life threatening.
There are, as of yet, no studies on the effects of fireworks on the population. While
individual fireworks in many cases have a negligible impact on populations, the use of
extensive fireworks across a wide area, such as is the case on New Year’s Eve in densely
populated Central Europe, can lead to population losses. The results of this overview
demonstrate that, in varying ways, fireworks increase the risk of mortality for individual
birds and, thus, the death rate of the bird population. For populations with an unstable
conservation status, negative trend or small population size as well as for sensitive
species types (birds that flock or breed in colonies), the conservation status can worsen.
Conclusions and possible consequences are briefly sketched for the handling of fireworks
in Germany. The “Bundesnaturschutzgesetz” (German Federal Nature Conservation Act)
and “Tierschutzgesetz” (Animal Welfare Act) must be consistently applied in cases where
animals are intentionally killed or injured. Despite considerable unknowns regarding the
dimensions of the damage for small birds, for the present it is assumed that no regular,
significant disturbance by fireworks occurs to common and widespread species. Minimum
distances from nest locations are specified for species that are rare or endangered as well
as for species that are more sensitive to disturbances and breed in colonies.
For resting areas of international importance, no more than 1% of the area may be
affected by fireworks; for areas of regional or national importance, this may be no more
than 10% of the area. A minimum distance of 1000 meters is also to be maintained
around areas for flocking birds – regardless of the protection status of the species and the
area. Particularly for sensitive species, such as the crane, an increased minimum distance
of 2000 meters is to be maintained. If reflecting structures exist around the resting areas
(e.g. buildings, hills, cliffs and dunes) or if water or other sound-carrying surfaces exist
between the resting area and the launching area for the fireworks, the minimum distance
must be doubled – and the same applies during hunting season. Power lines must not run
within a radius of 1000 meters from the resting area and the launching area for the
When approving fireworks, the spacial and temporal effects of the firework display on the
environment must be considered. The time interval between 2 firework displays at the
same site must be at least 4 weeks, and the physical distance between 2 firework displays
on the same day must be at least 10 kilometers. Authorities could increase control of
fireworks by implementing regulatory measures (e.g. in national parks and bird
conservation areas as well as in the area of bird breeding colonies and bird roosting
sites). Extremely loud explosion effects (flash crackers, etc.) and percussive charges
along water, along the coast, near protected areas, breeding colonies and roosting sites
must be eliminated.
The effectiveness of the measures must be monitored through random spot-checks and
then improved as necessary. It must be noted here that simple before and after counts are
not sufficient. In every case, the counts must be combined with observations during the
fireworks and, as possibilities permit, supported by technical means (night vision devices,
video recordings, photography, camera traps, etc.).