Nature is harsh, unpredictable, relentless and doesn’t distinguish between species or age or whether a creature is cute or not. Death is a part of nature, and, while many people might not usually see it, it happens a lot, and those of us who are living out here in nature see it every day. There are of course many causes of death within the seabird colony and, when you’re a little tern chick, you’re the most vulnerable to all of them. So you can probably guess where we see the greatest mortality out here on the island.
There are more than two thousand nesting pairs of terns here on Seal Island National Wildlife Refuge. Each pair pops out between one and three tan, beige, off-white, brown or dusky eggs spattered with dark speckles, perfect for blending in to the granite rockscape. This is the start toward new life, but there are a great deal of challenges ahead for this tiny, burgeoning being. Adult seabirds are drawn back to the nesting islands here in the
Gulf of Maine each spring to take on another nesting season and see their newly hatched young enter into a world that is exceptionally big for such a little seabird. Unfortunately, that world isn’t very kind to tiny, fluffy tern chicks.
Predators are a major threat to every colony on Project Puffin and our main culprit is the ever-present gull. Even before the chicks have hatched, tern eggs are at great risk from Herring and Greater Black Backed Gulls, which will weather a storm of sharp tern beaks in an attempt to grab an egg, or a chick that hasn’t ducked under cover in time. The terns are pretty vicious, but not enough to keep the crafty gulls away from such a great source of protein.
As luck would have it, Seal Island is far enough away from the mainland to not have to worry about mammalian predators, although, ironically, just the other day we did find a raccoon among the rocks near the colony. This was somewhat of a major event as there’s not been a wild mammal (other than harbor and grey seals) on this island in Project Puffin’s entire history. If it had reached the colony, it could have had a feast that might have ruined the tern’s entire nesting season.
Another predator, one I have great affection for, is the Peregrine Falcon. You can tell when she’s around because the entire colony goes silent and “dreads”, completely in unison, the entire colony in rapid flight radiating outward and suddenly dropping down toward the water. That’s when you want to keep a sharp lookout for this speedy aerial predator that might very well snap a tern out of mid-air right in front of you. Nick had one land right in front of him on an early morning blind stint, grasping the unfortunate adult tern in her talons.
Tern parents of course have a huge roll in chick survival and lack of experience can have a heavy toll on eggs and young chicks. Sometimes, walking around the colony early in the season, you’ll notice dead eggs. This could happen if the egg wasn’t fertilized or the if the parents don’t incubate, which could be for any number of unexplained reasons but is likely because the parents were inexperienced.
Once the new chick makes it out of the egg, it needs to dry off before getting a chill. The fluffy new bit of life soon realizes it needs food, and lots of it. With two adults working almost around the clock, these little guys grow fast, as much as 15 grams a day! They rely on a steady income of protein-rich hake, lancefish, pollock, lumpfish and shrimp-like euphausiids (to name a few) to grow in weight and replace that fuzzy down with pinfeathers.
The birds rely on an ample food supply to grow healthy chicks, but overfishing and climate change can affect population, range and availability (at this time of year) of the young fish which are of a size that can fit into a chick’s maw. In 2013, the nesting season followed an unusually warm summer and consequentially, the warmer water loving butterfish arrived in such great numbers that that was the majority of what the terns were bringing in. Unfortunately, this package of protein is of a shape and size that tern chicks have real trouble fitting them past their open beaks. Butterfish are a coin-like fish, flat and wide and neither tern nor puffin chicks could get the majority of these fish down, which resulted in lot of starved seabirds, next to a pile of unswallowed butterfish. You can’t convince a tern or puffin to catch anything other than that which is highly available and in their face when they take a dive, so they can’t really be blamed.
When the parents do bring in a nice, meaty hake that’s great for a healthy growing chick there’s more for that chick, particularly the tern chick, to worry about before it can swallow it down. Siblings! Terns usually lay two and sometimes three eggs so that means when you have one or two brothers or sisters going for that same juicy fish your parent is bringing in, wanting (and needing) it just as much as you do, you’ve got some serious rivalry going. And, of course, the biggest chick has the biggest advantage. Three heads reaching in desperation for the pollock hanging from daddy’s mouth, only one chick is going to nab the prize, and it’s usually the biggest and the fastest. Multiply this by all the feedings throughout the day and there will be definite leanings toward the oldest chick, meaning the younger chicks fall by the wayside.
Kleptoparasitism can really affect terns and puffins trying to teach their young, this is when a bird steals the food of another, meaning all that effort to catch a fish and fly back to feed it to its young is lost and the chick remains unfed. Common terns are aggressive kleptos, laughing gulls are also known for it, ganging up on a puffin zooming in with a beak full of fish.
Adult birds in survival mode are thinking only of themselves and their chicks. Neighboring chicks mean less food for their young (in a roundabout way) and perhaps innately, an adult knows that. What results is intolerance of nearby, neighboring chicks and adults can be pretty vicious toward them. There definitely are cases of infanticide, which is hard to stomach, but is another part of what we see out here on the seabird islands.
Nature, in all it’s forms, can be surprising to some. While you want the fuzzy babies to
grow up happy and strong, they’ve got a lot of confrontations to overcome and not every chick makes it. The reality of nature is something we confront every day, here on Seal Island. But the result is ultimately a robust, resilient population that can take on the challenges of becoming adults and surviving to produce their own young.
Nature isn’t always pretty, but isn’t it extraordinary!.