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Birds and Bees. Honey Bees. If a foraging bee finds flowers, after it has gorged on the nectar it flies back to the hive and then returns to the flowers with companions who take their fill of nectar. Bees can not only tell their companions that nectar is available but where it is found.

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Honey bees
Honey Bees

  • If a foraging bee finds flowers, after it has gorged on the nectar it flies back to the hive and then returns to the flowers with companions who take their fill of nectar.

  • Bees can not only tell their companions that nectar is available but where it is found.

  • Hive mates learn what type of flower to look for from the scent attached to the scout’s body and the location of the flower from the type of dance.


Round dance
Round Dance

  • If the nectar is within 50m of the hive the scout will do a “round dance”.

  • It enters the hive and runs on the combs where it is immediately surrounded by other bees.

  • It disgorges a drop of nectar from a honey sac and begins to dance.


Round dance1
Round Dance

  • It’s dance is in the form of a circle going first clockwise and then anticlockwise.

  • Having told the nearby bees it moves to another part of the hive where it repeats it’s dance.

  • While it is doing this, other bees take off and reach the flower.

  • The dance takes place in the darkness of the hive.



Waggle dance
Waggle Dance

  • The “round dance” does not indicate the direction of the flowers and is only used if the flowers are close to the hive.

  • Bees perform a “waggle dance” for flowers that are further away.

  • It indicates not only how far away the flower is but also the direction.

  • This is where solar navigation comes in.


Waggle dance1
Waggle Dance

  • The scout traces a squat figure 8.

  • The speed with which the bee dances round the figure 8 and the number of “waggles” it does on the straight turn gives the distance.

  • A slow circling and few waggling means the flowers are a far way off, while a quick circuit and rapid waggles means it’s closer.

  • E.g. If a flower is 100m away the scout will do 11 figure eights in 15 seconds. When the nectar is more than 1.5km away it did 4 figure eights in the same time.


Waggle dance2
Waggle Dance

  • The direction of food is given by the direction the bee is facing when it makes its straight run between the loops of the figure eight.

  • If the direction of the straight run is straight up, the source is in the direction of the sun; if it’s down the source is away from the sun.

  • The angle to the left or right of the straight run indicates the angle left or right of the sun to reach the nectar.

  • This means that the honey bee can take an angular measurement and fit it into a linear path – a truly amazing feat.


Waggle dance3
Waggle Dance

  • The bees keep the sun on one ommatidium during the outward journey and on a corresponding opposite ommatidium on the return journey. If the day is cloudy, bees can use polarised light to navigate.

  • Bees not only dance to show where food is in relation to home, but also to find new homes when the old queens swarm.



Birds
Birds

  • In 1950 a young German scientist, Gustav Kramer, realise that caged birds became very restless about the time they would normally migrate.

  • The birds would take off in the same direction as they would have flown on their migration.

  • He set up a series of experiments to test this behaviour. First her showed that the behaviour only happened when the birds could see the sun. On overcast days they had no direction to their movement.


Birds1
Birds

  • He then made some cages where he was able to change the direction of the sun by means of mirrors. He found the birds orientated themselves towards the new sun.

  • The migration pattern changes if a mirror is used to change the apparent direction of the sun. The birds use the position of the sun to calculate their migration.


Birds2
Birds

  • In another set of experiments, he placed food boxes around the cage but only put food in one. The boxes stayed in the same place, but the position of the food boxes could be changed in relation to their surroundings by revolving either the inner cage containing the birds or the outer wall.

  • The birds could only see the sky through the glass roof but as long as the birds could see the sun, they went straight to their food.


Birds3
Birds

  • On overcast days, however, the birds were disorientated. The birds knew where the sun was supposed to be in the sky at any given time.

  • This behaviour seems to be innate, because in an experiment a young bird which had been raised without ever seeing the sun was able to orientate itself quite well.