New research explores the mechanics of how birds flock

JUNE 4, 2019

by University of New Orleans

Wildlife researchers have long tried to understand why birds fly in flocks and how different types of flocks work. A new study from the University of North Carolina at Chapel Hill explores the mechanics and benefits of the underlying flock structure used by four types of shorebirds. Understanding more about how these birds flock moves researchers a step closer to understanding why they flock.

The study, led by Aaron Corcoran, a postdoctoral researcher studying bat and bird flight and ecology, and biology Professor Tyson Hedrick of UNC-Chapel Hill, appears in the June 4 issue of eLife.

In the study, the researchers focused on four types of shorebirds that vary in size: dunlin, short-billed dowitcher, American avocet and marbled godwit. Corcoran and Hedrick filmed and analyzed almost 100 hours of video footage to better understand the mechanics of shorebird flocks. They found that the birds fly in a newly defined shape the team named a compound V-formation, which they believe provides an aerodynamic advantage and predator protection.

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Willow tits survive best with support from a flock

December 18, 2018, Norwegian University of Science and Technology

Willow tits (Poecile montanus) generally reside in one territorial area throughout their adult lives. But brutal winters in the north kill off many of them. They aren't able to manage well on their own, and storing seeds in the autumn is not always enough. For the young of the year, it is absolutely vital to find a flock to spend the winter with. Juvenile birds also have to try to become high-ranking members within the flock.

Professor Emeritus Olav Hogstad at the Norwegian University of Science and Technology (NTNU) has banded and followed willow tits in the Budal area in Trøndelag county from 1986 to 2014. He has observed both mated pairs and single birds and has compared their survival. Hogstad and Professor Emeritus Tore Slagsvold at the University of Oslo have now jointly published their results in the journal Ornis Norvegica, published by the Norwegian Ornithological Society.

The period after fledging is a dangerous time for young birds. This is a time when the offspring are driven away from their kin and forced to move out of the territory where they were born. "The youngest birds, this year's offspring, experience much higher mortality than the older generations," Hogstad says.

The young birds need to find a flock to be part of, but there isn't room for everyone. Joining a flock, with the hope that they can take over the territory some day, is their ticket to survival. Survival is also linked to early flocking. Birds that manage to establish their place in the flock in the early autumn have much better odds of attaining a higher social rank, and thus of surviving. Body size does not seem to play any part in survival. Birds in a flock can learn from each other, and more birds are available to detect enemies like a hawk or an owl.

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Pigeon flock members can 'overrule' incompetent leaders

Date: September 14, 2016

Source: Oxford University

Flock leaders who attempt to give their fellow pigeons incorrect information about their direction of travel can be overruled by the collective wisdom of the group, according to new research from the University of Oxford.

Recent modelling work has predicted that the mistakes of a misinformed leader will propagate down a hierarchical decision-making system such as a pigeon flock. However, using a method known as 'clock-shifting' that interferes with pigeons' sense of direction, researchers have shown that bad leadership can be overcome, setting the flock back on the correct course.

Research from the same group at Oxford has previously found that the fastest pigeons tend to become flock leaders, rather than the most competent.

The new study is published in the Royal Society journal Biology Letters.

Lead author Isobel Watts, a doctoral candidate in the Oxford Navigation Group in the University's Department of Zoology, said: 'Previous research in homing pigeons has identified a navigational leadership hierarchy where an individual's position in the hierarchy reflects its weight of contribution in the decision-making process. In this study, we were interested in how much control the "top" bird actually has over the flock's decisions during homing. Do the top leader's decisions simply cascade down the hierarchy, or are lower-ranked birds also able to influence the direction in which the flock flies? By manipulating the quality of the leader's information, we hoped to discover whether a poorly informed leader was still allowed to lead or whether the flock would "overrule" inaccurate leadership.'

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