Catch Up #4 - What Did the Birds Tells Us?

“Perhaps the birds are just late in arriving this Spring? We’ve had that happen before”.  So, the conversation evolved in the Spring of 2021 as we perched on logs and tailgates, leisurely enjoying our traditional breakfast of granola, yogurt and fruit, debriefing our just completed early morning monitoring of forest birds.  Agreeing that something about the count did not feel right, we made the logical leap to exploring what hypothesis might provide a credible explanation.  What we noticed was that at each of the twelve point count locations along the mile and a half loop through the forest, the numbers of birds and species heard during each of the three minute counts were lower than we’d either expected or previously experienced. At the end of the second of three counts, spaced roughly a week apart, it was clear to us all that something was different.  Where were the birds?  Why weren’t we hearing their calls and songs in this forest as strongly as was normal?

The sequence of steps that we were subconsciously progressing through is as old, I assume, as our species.  First we notice – then we wonder – then we come up with an hypothesis that might explain the change – then we test the hypothesis  - finally, if the test suggests that the hypothesis is false, we revise and retest.  On that morning, we were struck by the low numbers of birds.  This led us to wonder what might explain this.  Our first hypothesis – “the northbound migrants are later than usual, but would still be arriving”, was a logical choice, based on how often we have encountered this in the past.   What light might the testing of this hypothesis in our third and final count shed on its validity?

Nine days later, we, once again, found ourselves enjoying our post-count breakfast and returning to the questions.  The answer to whether the “the migrants are just late” hypothesis was clearly visible on the checklist of birds and stops attached to the clipboard lying on the ground at our feet.  Neither the number of species nor individuals in each species had rebounded from the previous two counts; if anything they were lower.  Absorbing this invalidation of our hypothesis, conversation shifted to possible alternative explanations.  Might there be other deviations from what we normally experience that should be considered?  Reaching for a hardboiled egg, one of our expert birders reminded us what an abnormally warm and dry Spring it had been.  Taking this into consideration, she hypothesized “perhaps this abnormal weather has led to the forest producing less of the food that the migrants need and count on?”.   We ate in silence as we considered this new, possible explanation.  Driving home we discussed how we might better understand and test this alternative explanation.  We agreed that one test might be whether the numbers rebounded in subsequent years.

Several years on, we now see that the numbers have indeed rebounded – and that the warm and dry Spring of 2021 seems to have been an anomaly.  This brings us back to a basic dilemma that we may never have evidence to resolve in an intellectually honest way: were the weather conditions of that Spring linked in some way to human impacts on climate or are they unrelated?  Though I sense that we will never know enough to answer this question, that doesn’t keep us from the inevitable wondering and watching.  It seems that we can’t honestly attribute the weather to climate change, but we also can’t rule it out. As we continue to give our forests our best attention, it’s certain that this basic dilemma will be a constant, and in some ways haunting, companion.

So, what did the birds tell us in the Spring of 2021?  In the end, it is not clear what we conclusively learned from them, other than they were less numerous.  But this certainly stimulates our curiosity and attention.  Each Spring – and every day – forests, and their birds, have lessons to teach us – if we’re willing to listen and learn.