The European starling (Sturnus vulgaris) is a very accomplished mimic, able to reproduce a wide variety of sounds from its environment. This includes the songs of other bird species, as well as other noises like car alarms, telephones, and squeaky gates. Mimicry is the ability to imitate the sounds or behaviors of other species, and is quite rare in the animal kingdom. For a long time scientists have been fascinated by the European starling’s ability to mimic, and have studied it extensively to try and understand how and why it develops this ability.
What is Mimicry?
Mimicry refers to when one species evolves to imitate another species. This imitation can involve mimicking the visual appearance, sound, smell, or behavior of the other species. Mimicry provides an evolutionary advantage to the mimicking species, such as avoiding predation, attracting mates, or gaining access to food sources.
There are several types of mimicry:
– Visual mimicry – when one species looks like another, such as when a harmless species resembles a poisonous or dangerous species as a protective strategy. An example is the viceroy butterfly mimicking the appearance of the poisonous monarch butterfly.
– Acoustic mimicry – when one species imitates the sounds or vocalizations of another. This is what the European starling does when it mimics other bird songs or environmental sounds like car alarms.
– Olfactory mimicry – when a species emits the same chemicals or pheromones as another species in order to be perceived as that species. Many insects and plants mimic each other’s scents.
– Behavioral mimicry – copying the actions or movements of another species, such as predators mimicking the behavior of prey to get close to them.
Mimicry can be mutualistic and benefit both species, or parasitic if one species gains an advantage at the expense of the other. The European starling’s mimicry of other bird songs does not directly harm the mimicked species, so it is not parasitic mimicry.
Evidence of Mimicry in European Starlings
There is abundant evidence that European starlings are excellent mimics of other bird species. Here are some key research findings:
– Field studies have recorded wild starlings incorporating songs of up to 20 other species into their vocal repertoire. The most commonly mimicked species include wood pigeons, house sparrows, blackbirds, and song thrushes.
– European starlings maintain very high accuracy when mimicking the songs of other birds. Analyses show their renditions match the tone, tempo, structure, and notes of the original songs.
– Captive starlings have been extensively studied for their ability to mimic novel sounds. In laboratory experiments, they have successfully reproduced artificial sounds and computer-generated melodies.
– Juvenile starlings preferentially learn the calls of local species that they hear most frequently in their habitat. This supports mimicry being learned rather than innate.
– There are regional dialects in starling mimicking ability. Populations in an area tend to mimic the predominant local species, indicating vocal learning.
– Brain imaging shows that auditory feedback regions become highly activated when starlings are mimicking, allowing them to match their vocalizations to sounds they hear.
Overall, decades of research on vocal mimicry leave no doubt that European starlings intentionally imitate a wide variety of bird songs and other environmental sounds. Their mimicry ability is very advanced among songbirds.
Why Do Starlings Mimic?
There are several leading hypotheses proposed by researchers to explain why starlings have evolved such strong mimicry skills:
Innate Ability
One theory is that mimicry is an innate ability that starlings are genetically predisposed for. The ability to vocally mimic may have evolved as an adaptation for learning species-specific calls, and is present in young birds without any learning. However, field studies show that starlings preferentially mimic local species, contradicting the idea that mimicry is entirely innate.
Social Bonding
Mimicry may help facilitate social interactions between starlings. By mimicking the calls of other starling individuals or flocks, birds could increase bonding, coordinate actions, or signal individual identity. Vocal mimicry is thought to play a role in aggression and territory defense between starlings as well.
Mate Attraction
Another hypothesis is that males mimic elaborate songs to show off their vocal skills to females and attract mates. The ability to accurately reproduce difficult sounds demonstrates male fitness. Experiments do show that female starlings preferentially choose males with more complex songs.
Confusion of Prey
Alternatively, mimicry might help starlings acquire food. By mimicking bird alarm calls, starlings could flush nesting birds off their nests and steal eggs. Or mimicking the songs of competing species may distract them away from food sources. There is limited evidence for this theory so far.
Avoiding Predators
Finally, mimicking the warning calls or mobbing calls of aggressive species may help starlings avoid their own potential predators. This could function to deter predators, a form of auditory Batesian mimicry. Playback studies provide some support for this hypothesis.
The leading scientific consensus is that vocal mimicry in European starlings probably evolved for multiple purposes – mate selection, social cohesion, predator deterrence, and potentially accessing food sources. It likely serves different functions in different contexts. More research is still needed to fully understand this complex behavior.
How Do Starlings Mimic Sounds?
European starlings have several physical and neural adaptations that allow them to mimic other species with high proficiency:
– Syrinx – This vocal organ at the branch between the starling’s trachea and bronchi can independently control the sides of the sound source. This lets starlings create highly complex songs.
– Muscle control – Starlings have excellent neuromuscular control over their song production organs. This lets them closely emulate the tempo, pitch, tone, and rhythm of sounds.
– Auditory feedback – Brain regions compare the starling’s vocal output to the sound being mimicked and make real-time adjustments to match it accurately.
– Brain plasticity – Starlings can keep learning new sounds throughout adulthood because their brains remain plastic, able to form new neural connections.
– Specialized forebrain regions – Parts of the starling forebrain are specialized just for vocal learning and production. The association of auditory and motor regions in the brain facilitates mimicry.
– Critical period – Starlings have an early critical period after fledging when they preferentially learn new sounds. This primes them for acquiring mimicry skills.
Together, these specializations make the starling particularly adept at observational vocal mimicry compared to most other avian species. They have an inherent ability to replicate almost any sounds in their environment.
Impacts of Mimicry on Other Species
The European starling’s impressive mimicry ability may have some impacts on other species, but they are relatively minor:
– Confusion – Mimicked species may become confused or alarmed by hearing inaccurate renditions of their calls coming from starlings. However, there is little evidence this significantly impacts their behavior or fitness.
– Nest parasitism – There are isolated reports of starlings mimicking calls to flush nesting birds off their eggs and take them. But this is an uncommon behavior. Overall, starlings are not major brood parasites.
– Competition – Mimicry could potentially help starlings compete with other species for food and habitat by deceiving them. But many of the mimicked species do not directly compete with starlings.
– Hybridization – In theory, mimicking songs precisely could enable starlings to hybridize with other species. But in practice, no hybrids involving starlings have ever been recorded.
– Predator attraction – Mimicking warning calls or mobbing calls could make predators aware of the presence of prey. But the starlings themselves would likely be targets as well in this situation.
Overall, there is little evidence that vocal mimicry allows European starlings to significantly impair or outcompete other bird species. The mimicry does not appear to be parasitically exploiting other species. Instead it mainly serves social functions between starlings themselves. More research may reveal subtle impacts not yet discovered.
Other Bird Species That Mimic
While the European starling is a particularly adept song mimic, there are a number of other avian species that exhibit some mimicry ability:
Species | Mimicry Ability |
---|---|
Northern mockingbird | Mimics calls of 20-200 other species, extremely versatile |
Lyrebird | Elaborate mimics, copy sounds like camera shutters and chainsaws |
Indian hill myna | Can mimic human speech, pet sounds, other birds |
Australian magpie | Occasionally mimics other avian vocalizations |
Budgerigar | Popular pet known for mimicking household noises |
These mimic species demonstrate that vocal imitation is relatively widespread, though few match the European starling’s prowess and versatility. The ability has independently evolved in multiple avian lineages, conferring advantages like attracting mates, deterring predators, and facilitating social cohesion. Mimicry remains an intriguing behavior that provides insight into avian intelligence and adaptations.
Conclusion
In conclusion, extensive scientific evidence confirms that European starlings are prolific mimics, able to reproduce a diverse range of sounds with high accuracy. They preferentially mimic local species that they commonly hear during a critical learning period. Their mimicry appears to serve evolutionary purposes like attracting mates, bonding with other starlings, deterring predators, and possibly manipulating competitors. But overall it does not seriously harm the mimicked species. Understanding this complex behavior provides fascinating insight into avian intelligence, adaptations, and vocal abilities. European starlings remain one of the most talented avian mimics known.