Communication is vital for animals to survive and reproduce in their natural habitats. However, human activities have created a lot of noise pollution that can interfere with animal communication and affect their behavior and ecology.
How do animals cope with this challenge?
How noise pollution affects primate communication
SEBASTIEN BOZON/AFP via Getty Images
Noise pollution is a growing problem for many animals, especially those that rely on acoustic signals to communicate.
For primates, vocal communication is essential for conveying information about food, mates, predators, and territory.
However, human activities such as road traffic, aircraft, and urban development can interfere with the transmission and reception of these signals, reducing their effectiveness and potentially affecting the survival and reproduction of the animals.
One way that primates may cope with noise pollution is by changing their communication strategies.
For example, they may adjust the frequency, intensity, duration, or timing of their vocalizations to avoid masking by noise.
Alternatively, they may use other modalities of communication, such as visual or olfactory signals, that are less affected by noise.
How pied tamarins use scent marking to compensate for noise
A recent study by researchers from Universidade Federal do Amazonas and Anglia Ruskin University investigated how one primate species, the pied tamarin (Saguinus bicolor), changes its communication behavior in response to human noise pollution.
The pied tamarin is a small monkey that lives in the Amazon rainforest of central Brazil. It is considered critically endangered by the IUCN due to habitat loss and fragmentation caused by urban expansion.
The city of Manaus now covers much of its geographic range, exposing the monkeys to high levels of noise from various sources.
The researchers followed nine groups of wild pied tamarins for 10 days each, using radio tracking and behavioral observations.
They recorded the occurrence and type of vocal and scent-marking behaviors, as well as the ambient noise levels in each area visited by the monkeys.
They found that the frequency of scent marking increased directly with noise decibel levels, suggesting that the monkeys used more olfactory signals to compensate for reduced vocal communication.
Scent marking is a form of chemical communication that involves depositing secretions from specialized glands on substrates such as branches or leaves.
Pied tamarins use several types of scent marking, such as urine washing, anogenital rubbing, and sternal rubbing, which have different functions and convey different information about the sender's identity, reproductive status, and territorial boundaries.
The researchers also found that the type of scent marking varied depending on the context.
For example, urine washing was more common in areas with higher noise levels and lower visibility, while sternal rubbing was more common in areas with lower noise levels and higher visibility.
This suggested that the monkeys modulated their scent-marking behavior according to the environmental conditions and the information they wanted to transmit.
The study is the first to investigate how primates change their communication strategies in response to noise pollution.
It shows that pied tamarins are flexible and adaptive in their use of multimodal communication, using both vocal and olfactory signals to cope with challenging environments.
However, the researchers caution that increasing scent marking may have energetic costs and may not be sufficient to overcome the negative effects of noise pollution on primate communication and social cohesion.
Therefore, they recommend that conservation efforts should include reducing noise levels and preserving natural habitats for this endangered species.
