Birds in urban areas getting less shy to humans

Kathmandu, Dec. 31: It has been found that birds living in urban areas are more tolerant of human presence and do not feel the need to fly as far as rural birds do. Urban birds tend to flee from humans at shorter distances compared to their rural counterparts.

Rapid and unplanned urban growth is significantly affecting bird behaviour, helping them adapt and coexist in urban environments, according to a study “Flight Initiation Distance and Bird Tolerance to Humans in Rural and Urban Habitats.”

The study conducted jointly by Amrit Nepali, Hem Bahadur Katuwal, Sabin KC, Sandeep Regme and Hari Prasad Sharma, focuses on the Kathmandu Valley, a rapidly urbanising place in South Asia. It examines the Flight Initiation Distance (FID) of 33 bird species as a proxy to assess their tolerance towards humans in urban and rural habitats. The Kathmandu Valley, is home to over 500 bird species, serving as a crucial stopover site for migratory water birds and wetland birds, the research said.

Hari Prasad Sharma, one of the researchers, said, “We conducted this study in Kathmandu Valley, encompassing the administrative districts of Kathmandu, Bhaktapur, and Lalitpur. This area is in the mid-hills region with elevations from 1200 metres to 2760 metres and temperatures from 0 degree Celsius to 35 degrees Celsius. Kathmandu Valley provides a wide range of habitats for birds including forest, settlement, farmland, grassland, rivers and lakes.

According to Sharma, the study measures the distance at which a bird takes flight when approached by a human. Researchers conducted surveys in both urban and rural areas, recording data on the time of day, bird behaviour, sex, flock size and dietary guilds. To minimise biases, researchers avoided approaching birds in areas with potential disturbances, such as temples or residential compounds and wore neutral clothing. The study collected 922 FIDs from 33 bird species, with 505 FIDs recorded in rural areas and 417 in urban areas.

The study found that birds in urban areas exhibited significantly shorter FIDs, indicating higher tolerance to human presence compared to their rural counterparts. This increased tolerance is likely due to reduced risk risks and habituation to human activities. For example, urban areas often have people feeding birds in parks and temples, which they may perceive as non-threatening.

Birds showed higher tolerance in the morning compared to the afternoon, likely due to energy requirements after nighttime fasting. Morning foraging needs may reduce their alertness to potential threats.

“Urban birds exhibit unique adaptive traits, such as smaller body sizes, diminished territorial behaviour and greater dispersal abilities, enabling them to thrive in densely populated areas. These adaptations may include larger clutch sizes to offset lower survival rates and longer lifespans to endure urban environmental changes. 

However, these behavioural shifts can have implications for their survival and reproductive success,” research said.

The research also said that birds exhibited longer FIDs in summer than in winter, possibly due to increased food availability and breeding season dynamics, which heighten their awareness of potential threats.

The findings also highlight variations in tolerance related to sexual dimorphism (two distinct forms of a species) and migratory status. For instance, monomorphic birds showed longer FIDs than dimorphic species, possibly due to differences in predation risk. Migratory birds, unfamiliar with local environments, exhibited longer FIDs compared to resident species, underscoring the importance of familiarity and behavioural plasticity, according to the research.

Dr. Hem Sagar Baral, a noted ornithologist, said that the study examined how birds adapt to predators, (humans considered as predators in this context). “Similar research has already been conducted in Europe, and it’s encouraging to see such studies being carried out in Nepal as well. This research highlighted the interaction between humans and birds in both urban and rural areas,” he said.

He added that the level of tolerance varies among bird species in different areas. For example, pigeons tend to be more tolerant of human activity than other birds. Species like crows, sparrows and others have varying levels of tolerance, depending on their specific characteristics and environmental factors, Dr. Baral said.

“The birds also can read body language and they can see from a long distance. The birds also notice people, when they feel danger, they tend to fly faster and if they feel safe, they become friendly to humans,” he added.

According to the research, understanding the factors influencing bird tolerance is crucial for developing effective conservation measures. By fostering coexistence and protecting habitats, we can ensure the survival of avian species in rapidly urbanizing environments.