Report from Plymouth Branch Indoor Meeting held on Monday 27 March 2023
What is a bird? To understand this more fully, Ian used his extensive experience as a much travelled birder to try to unpick this question.
Birds are unique in the wildlife of our planet – warm blooded, egg laying, vertebrates with feathers covering their bodies. But what do we know of their behaviours and their evolution? Ian looked at various aspects of their behaviour related to physiology, movement, feeding, intelligence, breeding and migration. These are all large topics in their own rights but provide a good way to try to more fully understand these amazing creatures.
We learnt how the behaviours of birds are related to their positioning in our planet’s ecology and how the structure of birds is uniquely adapted to (in most species) allow flight with honeycombed skeletons, specially developed hearts and lungs and with up to 25% of the bird’s mass made up of flight muscles.
Feeding too shows many adaptations of beak, legs and associated feeding methods; all playing a part in the evolution of birds – think of Darwin’s finch studies as an example of evolutionary process.
Ian also exploded the ‘bird-brain’ mythology and showed us examples of the intelligence and learning capabilities of many species. Interestingly he compared the Macaw to the Chimpanzee in terms of brain size to body ratio – the same! This is reflected in the abilities of the Macaw such as being able to mimic speech.
Birds also sing. Who hasn’t been inspired by the soaring song of the Skylark or the melodious dawn chorus of the Blackbird? How does a bird sing for long periods of time and fly at the same time? Again, bird physiology has developed to make this possible. Why do birds sing? In short, ‘love and war’, signalling territories and attracting mates and there will be differences in timing due to breeding constraints also connected to feeding needs and prey availability when raising their broods.
Migration, both international and intra-national, has fascinated us and we continue to learn more as technology, such as electronic tracking devices, aids our understanding. We know that birds respond to changing light levels and that spurs them to migrate and some epic journeys are made. Migration within countries also happens, e.g. mountain breeding birds moving toward the warmer coastal areas where food is more plentiful. It is more often lack of food sources rather than low temperature that can decimate bird populations in winter months.
We learnt much from this presentation but we also realised that there is still much that we don’t fully understand – but maybe that’s part of the magic of bird watching.
John Lloyd Committee member Devon Birds Plymouth Branch
