2018 Least Tern Floating Habitat Project

In 2016 the barge layout was changed from two separate barges into one large nesting area in hopes of enticing a larger breeding colony. In 2015 we experienced a predation event from a raccoon that could have potentially been thwarted by a larger colony. Starting in 2016, to assist with that effort we also installed a solar powered, single strand electric fence that should be effective at keeping mammalian predators off of the barge.

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Barges were positioned in Ellis Bay 2009 - 2014
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Barges were moved to Teal Pond before the 2015 season.

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Two barges lashed together


In 2016 we monitored the nesting progress from late May through July 25th. We recorded 20+ nests, with a total of 65 eggs. Over 50 adult terns were counted at once, but the number of nests suggests that there may have actually been closer to 60 adults in the area.

World Bird Sanctuary came out to Riverlands in 201? for two banding attempts. The first was on July 6th and the second date was July 25th. On the first banding trip, 42 chicks were banded with 20 eggs unhatched in nests. An additional nest was initiated shortly after the first banding attempt. This resulted in 23 chicks being banding on the July 25th date. Each banded chick was fitted with a red leg plastic leg band as a year identifier, and a metal leg band (see images below).

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2016 and 2015 Summary

Least Tern Floating Habitat Project
The Least Tern nesting barges had no successful nests in the 2015 season. Timing of barge placement as well as extended periods of low water corresponding to nest site choice timeframe were noted as possible causes for the lack of success.

The barges were moved to Teal Pond before the start of the 2015 seson. The water level is more stable there and a static location for futue years should help attract returning terns.

A few things had been changed prior to the 2016 tern nesting season; one was the purchase and installation of high definition game cameras, one per barge. The ability to continuously monitor barge activity for predation and breeding activity was an irreplaceable tool in the efforts of figuring out the problems that this project was up against. We made the decision to remove the overhead rope barrier off of Barge #1. (Barges were given names to distinguish the two for nest monitoring purposes. Barge #1 is the Southern-most barge and Barge #2 is the Northern-most barge). This decision was based on the photographic evidence of fish crows, with the reasoning for this action being tied directly to the fact that the fish crows were already able to pass through the overhead barrier, with hopes of more terns choosing to use the barge with an easier access after the barrier was removed. A larger tern colony should have more success in repelling would-be predators, such as the fish crow.

The first observations made by RPO staff occurred on 19 May 2016. The next day, 6 terns were observed flying around Teal Pond and Ellis Bay, and perching on the barge buoys.

Sightings were fairly regular in the vicinity of the barges until around the 1st of June. No terns were observed in a survey again until 17 JUN, when a single tern was observed near the Mel Price spillway. This was followed by a sharp spike in tern activity and photo-verified barge nesting use. All nesting at this time occurred on Barge #1, which was the barge with the overhead rope protection removed. Peak tern numbers were on 30 JUN, with a total of 18 terns observed in Teal Pond and Ellis Bay. Chick boxes and shelters were placed on the barges during the 29 JUN trip in anticipation of soon to arrive hatchlings.

The nests suffered a severe attack from a raccoon on the night of 09 JUL; an earlier count had revealed a total of 23 eggs among 10 different nests. Of which, a single nest containing 3 eggs was left intact after the predation event. A predator of this nature was not expected. The chain link fence is 5ft in height; and the nearest terrestrial habitat is over 175 meters to the north. This animal had to swim over 1/10th mile; then climb the anchor line up to the barge, and then scale the chain link fence. We anticipated the possibility of river otter, but were confident in the ability of the fence to deter them. A raccoon willing to swim that distance was not foreseen; and completely caught us off guard. Also, it seems that the terns’ ability to mob the predator and deter its attempts appeared to have been futile at best.

Despite the severe disruption on the barge by a raccoon; one nest managed to come away unharmed. In fact, 3 days later, that nest hatched all three eggs. In subsequent weekly trips to the barge for nest monitoring, photos were taken of the young as they grew.

Based on survey data, the family of terns with the new fledglings left Riverlands at some point during the week of 08 AUG 2016. The last observation of these fledglings occurred on 09 AUG 2016.

At that point most of the attention had already begun to shift toward Barge #2, where a secondary nesting attempt after the predation event (nesting behavior was observed on Barge #2 less than one week later) had resulted in a nest containing 2 eggs. These eggs were first observed on 20 JUL. A trip to the barge to search for hatchlings showed that one of those two eggs had hatched very recently. The game camera had not picked up any photographic evidence, however, due to the close proximity of the game camera to the actual nest (the camera was aimed just over the nest, out of frame).

On 09 SEP 2016, the last remaining juvenile was spotted perched on a buoy near the barges. This individual had obviously taken flight, was expected to have migrated south with the adults at some point near shortly after this sighting


Tentative future plans for the 2017

Tern Nesting season have already begun. The changes include barge configuration and placement, and perhaps some island work to be completed at a later date within the confines of Teal Pond.

For the barges, one possible scenario would include lashing the two back together to provide a larger contiguous nesting area to hopefully entice a larger colony onto the barges. The larger colony should, in theory, be more efficient at defending against would-be predators. No plans are in place for the overhead protection on the barges, as it was observed that the barge without overhead protection was colonized first appears to be the most optimal choice. Another plan includes cutting the fence walls to about the 3ft height range. This will allow for a more natural flight approach, rather than a straight down drop of 5 or more feet. We do not feel as if the 5ft height of the fence was any better deterrent to the predators as a 3ft height fence would be, and thus, choosing a 3ft height may also assist in enticing more terns to colonize, and hopefully resulting in a stronger more defensible nesting strategy.

Note: Above update is from a Lane email.

Text below is another email update not incorported above yet.
"Attached is a document with three years of barge summaries. We counted 67 eggs and 6 hatchlings on Tuesday this week (6/12/18), so as long as we don't have any serious predation events it should be a good season!"
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