Swallows are widely recognized as harbingers of spring. Spring in turn is regarded as the season of change. And change is part and parcel of evolution. And evolution itself seems to have accelerated recently.

And now the best bit: swallows seem to be evolving to become better at… jaywalking. So, ultimately this entire evolution thing may prove to be a bitter pill to swallow(s).

Check out: Swallows May Be Evolving to Dodge Traffic




  • hasty – made or done with haste or speed
  • oncoming – approaching, nearing
  • presumably – by assuming reasonably, probably
  • conical –  having the form of, resembling, or pertaining to a cone
  • decline – to fail in strength, vigor, character, value, etc.
  • rule out – to prove to be unrelated or not for consideration
  • capacity – actual or potential ability to perform, yield, or withstand


Think about it


  • In what way are shorter wing beneficial to swallows?
  • What two findings prove evidence of roadway-related adaptation?
  • Describe the swallows’ nesting habits.
  • What are some other factors which may have caused the decline in roadkill?
  • Do scientists have hard evidence of the swallows’ evolution?


 Practice makes perfect

Put the words in capitals into correct forms.

Roadside-nesting cliff swallows have ______ EVOLUTION shorter, more ______ MANEOUVRE wings, which may have helped them to make hasty retreats from ______ COME vehicles, according to a study published in Current Biology.


Put the verbs in brackets into correct tenses.

As the two researchers ______ (check)  the roadside colonies, Brown, an amateur taxidermist, ______ (collect) dead swallows for skinning and stuffing — gathering 104 vehicle-killed adults and 134 adults killed accidentally in nets used for the study. When he and Bomberger Brown ______ (notice) a decline in the annual number of roadkills — even though the overall population ______ (increase) — they ______ (compare) the wing measurements of both types of stuffed bird.


Fill in the blanks with the missing words

The researchers tried to rule ___ other factors that might have explained the decline ___ roadkill — including changes ___ methods ___ find the animals, traffic patterns, predators, diseases and scavengers — but acknowledge that it might have been caused ___ behavioral changes, such ___ the birds learning to avoid cars.


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