The ugly truth behind those “cute baby bird” Internet memes
The ugly truth behind those “cute baby bird” Internet memes

          
          
By placing cameras near birds' nests in swamps (see below), the researchers found that alligators frequently hang out directly under the nests within chick-catching range, clearly hoping for the adults to toss them a snack.

    
              
                
              
                Alligators (red boxes) are observed under white ibis chicks (blue boxes) in wading bird nesting colonies. Here you can see the bird's-eye view from three nests. (A) and (B) are cameras placed near ibis nests; (C) is a camera facing down from an anhinga nest. 
                                  
                    Credit:
                                          Nicholas E. Vitale and Lucas A. Nell
                                      
                              
            
                  
          
    
    
      Alligators (red boxes) are observed under white ibis chicks (blue boxes) in wading bird nesting colonies. Here you can see the bird's-eye view from three nests. (A) and (B) are cameras placed near ibis nests; (C) is a camera facing down from an anhinga nest. 

              
          Credit:

          
          Nicholas E. Vitale and Lucas A. Nell

                  
          
  
        
            

Sympathy for the alligator
The facilitation between birds and alligators is clearly a two-way street, but that raises the question of whether alligators who team up with wading birds are actually better survivors than those who don't. Do alligators get enough chicks out of the bargain that they are actually more fit to reproduce?
According to the researchers, the answer is yes. They found this out the hard way, catching and releasing alligators by hand in the Florida Everglades.
In a section of their article delightfully called “alligator sampling,” the researchers explain that they conducted their research near the semi-submerged islands where wading birds nest in freshwater swamps. During several summer nights in June of 2013 and 2014, they captured and examined 39 female alligators—20 from areas where they lived in facilitative relationships with egret and heron colonies and 19 from areas where they didn’t.

    
              
                
              
                An alligator tries to chomp a raccoon at a Florida research station.
                                  
                    Credit:
                                          Florida Fish and Wildlife Conservation Commission
                                      
                              
            
                  
          
    
    
      An alligator tries to chomp a raccoon at a Florida research station.

              
          Credit:

          
          Florida Fish and Wildlife Conservation Commission

                  
          
  
        
            

By measuring the alligators’ mass relative to their length, the researchers determined that alligators who lived near wading bird colonies were healthier, with higher relative body mass. Their body masses were similar to those of alligators who choose to reproduce. The alligators who weren't in facilitative relationships were less likely to have a body mass that would make them want to breed.
The researchers write:

 The magnitude of benefits demonstrated here indicates that for alligators there should be selective pressure toward behaviors that enhance the benefits they derive from this association. We hypothesize that alligators are attracted to and, given their territorial behavior, may even compete for territories that include wading bird colonies.

Birds are, they add, are creating "localized nutritional subsidies" for the Florida alligators.
In the end, alligators are getting roughly the same benefit from the facilitation arrangement that the birds are. Alligators protect the bird eggs from raccoons; and the birds toss the alligators enough extra protein that they grow to breeding size more often than their counterparts. Seems like a nice arrangement, unless you happen to be one of those chicks who is too close to the edge of the nest.
PLoS One, 2016. DOI: 10.1371/journal.pone.0149572


          
                  