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Posts Tagged ‘Predation’

Photo by Wayne MacCabe

Photo by Wayne MacCabe

This is the Captain, who lives on the walkway in front of the house. What makes him so special to us is he was rescued from freezing rain when he was still inside his egg. One rainy day the area where Captain’s nest was got flooded with collecting rain water. The whole nest and the three eggs inside it were completely submerged in the water and were floating around. The parent was hovering over the nest, unsure of what to do. After seeing this I quickly ran outside and scooped up the nest and re-located it to a nearby high-elevated area. Seconds later Captain’s mother was back on her nest. I was relieved to see this because terns can be sensitive to any slight change to their nest and can be spooked away if they feel something is wrong. Unfortunately, I still didn’t have high hopes for the chick’s survival. I didn’t know how long the eggs were floating in the cold water, they could have passed away from the cold temperatures or from the water sealing up the pores on the egg which lets the chicks breath oxygen from the air. But, to my surprise about a week later Captain hatched and soon after so did his brother, Sailor. I named the chicks this because the nest was floating around like a ship at sea. Now, both Captain and Sailor are fledging!

We have over 2,000 chicks on the island and just our presence here increases the survival rate for these chicks. This is because we deter predators like greater black back gulls, peregrine falcons, herring gulls, and more which will make a quick meal out of the fledging terns and chicks. Realistically, we can not 100 percent stop predation from these species, but we work hard to keep fatality numbers low. Without us working here on the island these birds would likely take over and would have a devastating blow to the tern population. It made me so happy to see that Captain had made it but I noticed I gained a lot more than just satisfaction from seeing him survive, I gained a new understanding of my time here on the island. This event encouraged me because it really showed how my time and work on the island present on the island.

-Laura Bollert

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Sometimes it’s a hard life being a tern: there’s bad weather, trying to find food, and trying to avoid becoming food. Our research is not always done when the sun sets. Some predators will use the cover of night to their advantage. Because of this we use night vision binoculars to document what we would not usually be able to see. Our first predator stint shed light on the dangers that lurk in the tern colony with the coming of dark. At 10:30 pm a gull was seen walking around the edge of the colony which disturbed only a few Arctic Tern pairs. The next morning check led us to discover 5 empty Arctic Tern nests with evidence of a half eaten egg in one nest cup.

A look through the night vision binoculars on a cold island night.

The tern colony on Metinic has a few unique predators. Besides the usual wandering gull, the tern colony also must avoid egg/chick-eating garter snakes (invasive to Metinic Island), local sheep that escape past the fence and don’t watch what they step on, and a resident Merlin pair that will not only eat chicks but the adult terns themselves! Documenting all predation seen is an important part of understanding what the terns face when nesting on Metinic Island. This information is part of the big picture and helps us better manage the tern colony.

Another type of danger that poses a threat to all wildlife is human debris. Offshore Islands are not protected from litter that is washed ashore from the sea; even a refuge. This debris can be found on Metinic from the center of the forest to the edge of its shores. Common items are: plastic bottles, plastic containers, fishing gear, buoys, balloons, gasoline cans, rubber gloves, and even parts of ships. Human debris threatens life on land and in the sea. Many release toxic chemicals into the environment, some can easily be mistaken by animals as a food source while others can potentially entangle animals that come in contact with them. While living on the island we have and will continue to collect and properly dispose of the human debris that washes ashore but know that once we are gone the debris will continue to accumulate on the island. This is where you the reader comes in. Even if you are far away from Metinic Island you can still help the terns and other wildlife by disposing of your trash properly and picking up litter while out enjoying the environment. Remember first reduce, then reuse, and finally recycle. Together we can make our world a safer place for wildlife.

A sample of the debris that washes ashore on Metinic Island: plastic Vitamin Water, Plastic Pepsi bottle, rubber glove, plastic oil container, old lobster buoys and yards of rope.

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Tern on an egg (through the spotting scope)!

Life and death unfolds at an alarming rate here on Petit Manan Island. Thousands of eggs hatch every summer. At the peak of the season, Common Terns, Arctic Terns, Atlantic Puffins, and Black Guillemots (just to name a few) can be found on almost every surface and in every crevice on the island. But a whole host of predators are fully aware of this phenomenon – in June, PMI is ripe with adult birds, chicks, and eggs all ready for the picking. Peregrine Falcons, Bald Eagles, Harriers, Greater Black-backed Gulls, Herring Gulls, and Laughing Gulls are just a few of the predators that have already found a few meals on PMI this summer.

The Crew (minus Christa) painting popsickle sticks

The PMI Crew (minus Christa) painting popsicle sticks

In all this madness and mayhem, the research team is trying to get a gauge on the effects of predation on some of the species nesting on the island – especially Arctic and Common Terns. How many eggs are being laid and how many are being predated for each species? With several hundred nests already established, it’s a little difficult to keep track of such details! So over the years, the Refuge staff has devised a method of labeling nests with small wooden stakes – more commonly known as Popsicle sticks!

Stake indicating the nest number, species (COTE = Common Tern), date inserted and number of eggs, and the number of eggs at the check date

While observing the tern colony from the blinds scattered around the island, whenever we notice a nest we place a Popsicle stick (which we paint purple so that we can easily spot it on the ground) nearby that indicates the stake number, the date that the nest was discovered, the tern species, and the number of eggs in the nest. As that number changes (because more eggs are laid or because of a predation event), we update the stakes accordingly. At the end of the season we use this data to calculate success rates for each species.

Arctic tern on its nest, marked by a purple stake

The stakes will also come in handy when we do the big island-wide census, which is coming up soon! Check back for updates!

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