Do honey bee foraging distances vary according to season?

Are honey bees more likely to vary the foraging distances according to season?  According to a research paper, it seems likely:

Couvillon MJ, Schürch R, Ratnieks FLW (2014) -
"Waggle Dance Distances as Integrative Indicators of Seasonal Foraging Challenges".
PLoS ONE 9(4): e93495.  

Waggle Dance Distances And Seasonal Foraging Challenges 
  

Below is a summary of the research, along with a link to the paper.  More links and references to the foraging ranges of bees.

Research key points: 

• The researchers found that mean foraging distance/area significantly increase from springs (493 m, 0.8 km2) to summers (2156 m, 15.2 km2), even though nectar is not better quality, before decreasing in autumns (1275 m, 5.1 km2).

• The researchers state that as bees will not forage at long distances unnecessarily, this suggests summer is the most challenging season, with bees utilizing an area 22 and 6 times greater than spring or autumn.

• The researchers state their study demonstrates honey bees may be used as indicators, and can show through their dance the seasons in which forage is relatively less available and, by extension, when additional forage would be most beneficial.

Scope: 

The scientists investigated month by month and season by season variation in honey bee foraging distance over a representative rural-urban landscape.

In year 3, they determined the nectar sugar concentration returned by foragers, which they state correlates with quality sources. 

Method:

Three colonies in observation hives were used.  All three colonies were queen-right and were maintained throughout the duration of the project for swarm prevention and to keep the number of workers and amount of brood consistent.  The honey bees used were of mixed European subspecies, but predominantly the British black bee Apis mellifera mellifera, and colonies were unrelated.

The scientists observed the honey bee waggle dance behaviour, in which a successful forager honey bee communicates the location of visited flowers to nestmates, in order to make a 2-year survey of food availability.  In doing so, they  “eavesdropped” on 5097 dances to track seasonal changes in foraging, as indicated by the distance to which the bees as economic foragers will recruit, over a representative rural-urban landscape.

In year 3, the scientists determined nectar sugar concentration by analysing the regurgitations from foraging honey bee abdomens.

Results

The paper states:

• The data show that in summer compared to spring or autumn, the bees fly further to bring back nectar that is not better in quality.
  

• Honey bees, foraging over a landscape that is typical of most of the Western world, must travel further, covering a significantly larger area, in the summers (2156 m, 15.2 km2) compared to springs (493 m, 0.8 km2) or even autumns (1275 m, 5.1 km2) to collect forage that is not of better quality.

• In contrast to summer, during spring the bees danced for much closer locations, mostly within 500 m from the hives. 
  
  In many temperate habitats, spring is a season of great flower abundance, with woodland flowering species that bloom before the tree canopy matures, including trees, shrubs, perennial herbs and annual. Abundant flowers mean that bees are able to forage locally. 
  

• Even though the weather in autumn is less favourable than in summer, the dance decoding indicates that foraging conditions actually improved from summer to autumn. In the study area, ivy begins to bloom in August, with the first flowers seen on 29 August, 2009 and 14 August, 2010, and peaks in September and October.
  
  Honey bees feed almost exclusively on ivy for both nectar and pollen in the autumn and its ubiquity means that they can forage closer to the hive than in summer. Ivy nectar is also high in sugar (about 45%), which most likely accounts for the improved quality of autumn nectar compared to summer.

Read the full study.

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