2015 press release

Skagway's Arctic Tern Colony - 2015 press release

Below is a press release about Skagway's Arctic Terns which describes basic biology, history in Skagway, observations and disturbances from 2015.

It is also available as a downloadable PDF: 2015 Arctic Tern press release

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Press Release, 1 July 2015

Nov 2015 - map added

April 2016 - graph and text added

CONTENTS:

Reproduction

Predators and Disturbances

History in Skagway

Conservation Status

What happened this year - Observations

What happened this year - Disturbances

References

Humans aren't the only ones that come from great distances to visit Skagway each summer. A small colony of Arctic Terns travels all the way from Antarctica every year to raise their young here. Our tern colony has nested for many years next to the chain-link fence on the west side of the Ore Terminal, between the helicopter operation and the tank farm. At that location, they have become conditioned to periodic human disturbances and have successfully reproduced for many summers. It is the only place in Skagway Borough where people can easily watch tern nests and witness chicks growing from fuzzy balls to elegant adults.

This summer the nesting colony failed and the terns abandoned the site in early June. At about the same time, they were exposed to several large disturbances, the most intense being grading and stockpiling of gravel at the colony site. The colony may have experienced other stressors, including predation, overheating, and low-level human disturbances.

The Skagway Bird Club is not a political or advocacy group. “Opinions among our members about what should be done for the Arctic Tern colony are as varied as those within the whole community” said Elaine Furbish of the Skagway Bird Club.

As a group, the Skagway Bird Club offers this information about Arctic Tern biology and Bird Club observations to help people better understand these remarkable birds, and to help the community reach a consensus on what to do about our Arctic Terns.

"These amazing birds are expert flyers and beautiful to watch as they hover and plunge-dive for tiny fish to eat,” said Shelby Surdyk of the Skagway Bird Club. The terns mate for life and live into their mid-30s.^[1] During their lifetimes, they will migrate a distance equivalent to travelling from the Earth to the Moon three times over! ^[2]

Reproduction

Arctic Terns start reproducing around their 3rd year, and usually return to the area where they hatched to find their life-mate and start laying eggs.^[3] Their “nest” is just a scrape on gravelly ground, and they usually occupy their nests for 10-25 days before laying.^[1] Both parents incubate the clutch of 1-3 eggs, trading places so the eggs are rarely exposed,^[1] until eggs hatch after 20-23 days.^[4] If the parents are flushed from the nests during this time period, hatching can take up to 34 days.^[1] Chicks can stand and take food within 2-3 hours after hatching. ^[1] After 1-3 days, they leave the nest and find places to hide nearby.^[4] Both parents bring food and protect the young.^[4] The chicks practice flying about 22 days after hatching, and 4-5 days later will start flying away from disturbances rather than running to hide.^[1]

Arctic Tern with 2 chicks at Skagway Ore Terminal colony site, 2011 (M. Konsler)

Predators and Disturbances

Arctic Tern colonies can be affected by a number of predators – including fox, weasels, and river otters on land; and gulls, ravens and crows from the air.^[1] The terns prefer nesting sites on sparsely vegetated islands, remote beaches or gravel bars to avoid land predators.^[5] Without pressure from land predators, spacing between nests is about 1-9 yards apart, with land predators it increases up to about 55 yards apart.^[1] The spacing of nests at the Ore Terminal nesting site indicates that the terns were protected from land predators at that location. If an individual tern nest is destroyed early in the season, some terns may re-lay within a week or two.^[1] Arctic Tern colonies are good at adapting to predictable human activity, but may desert a colony if subjected to an unusual, intense, one-time disturbance.^[1]

History in Skagway

Arctic Terns have undoubtedly nested in the Skagway area for millennia. The earliest written record noting the presence of Arctic Terns here is from the year 1899.^[6] In the early 1960s, two Skagway residents remember being dive-bombed by Arctic Terns while strolling along the Skagway River. They started at the river mouth, walked upstream for about ½ mile, and were dive-bombed by terns when they got too close to certain gravel bars. Several Skagway Bird Club members recall that terns used to nest on the Skagway riverbed until the 1990's flood control and airstrip improvement projects, after which they concentrated on the Ore Dock peninsula. After the helicopter operation occupied the far end of the peninsula, the tern nesting area contracted to the fringes of the Ore Terminal staging area – the present location. The Klondike Gold Rush N.H. Park initiated a waterbird survey in 2003, and recorded Arctic Terns near this area every year from 2003 to the present.^[6]

Conservation Status

Arctic Terns spend half the year in the arctic and the other half in the antarctic,thus can be affected by habitat destruction at either locale. Their overall population size appears to be slowly decreasing, but their global range size and population size are extremely large, so they are evaluated as a species of “Least Concern” by the International Union for Conservation of Nature.^[7]

Arctic Terns are protected under the Migratory Bird Treaty Act,^[8] which prohibits taking of listed birds.^[9] Take means to pursue, hunt, shoot, wound, kill, trap, capture, or collect - or attempt to carry out these activities ^[9] - including intentional activities and unintentional activities that result from, but are not the purpose of, an otherwise legal activity.^[10] This is usually interpreted to mean that take does not include habitat destruction or alteration when there is not a direct presence of birds, active nests, or eggs.^[11]

What happened this year - Observations

The Skagway Bird Club's earliest Arctic Tern record for this year is approximately 5 terns seen in the vicinity of the Ore Dock on 1 May. In mid-May, a Bird Club member noted Arctic Tern eggs in a scrape at the edge of the colony nesting site. The nest was re-checked around 3 June, and an adult was sitting – incubating the eggs. A different Bird Club member recorded birds seen in the vicinity of the Ore Dock, not specifically at the colony nesting site, for about 6 days per week, starting mid-April 2015. This data set shows consistent tern presence from 3 to 28 May. One Arctic Tern was seen near the Ore Dock by a visitor on 11 June. Some additional sightings of terns were made during the last half of June, but no consistent presence of terns was recorded.

Arctic Tern eggs, mid-May 2015, at Skagway OreTerminal colony site (G. Heger)

ARTE abundance graph

Data from eBird observations in the area of the tern colony, over all years with data, show that Arctic Terns are typically found in the area from mid-April to mid-July.

The graph below shows that the Arctic Tern colony failed this year, since the birds were only consistently seen at or near the nesting site for about 30-34 days - not sufficient time occupying the nesting site to fledge chicks. The minimum time period needed to successfully raise chicks would be about 55 days: pre-laying occupation (10 days) + incubation (20 days) + ability to fly (25 days). A more typical time period would be about 63 days.

What happened this year - Disturbances

Around 1 June, heavy machinery was staged at the colony nesting site during an asphalt paving project nearby. Smaller vehicles sometimes parked at the same location without affecting the terns, but the larger, noisier vehicles using the area for a longer time period could have displaced some terns. However, the terns have been occasionally exposed to this type of disturbance in past years without resulting in abandonment of the site. Sometime prior to 9 June, the tern nesting area was graded. On 9 June, gravel began to be stockpiled at the colony nesting site. These were large, intense, unpredictable disturbances – the type of disturbance that would destroy any nests and chicks occupying the same space, and would cause the colony to be deserted.

gravel stockpile, Skagway Ore Terminal June 2015 (C.E.Furbish)

In addition to the large disturbances described above, individual nests, eggs or chicks could be lost to predation at any time. During a hooligan run from about 25 Apr to 15 May, thousands of gulls were in the area – gulls that might have harassed tern adults or eaten tern eggs, although gulping hooligan would have been easier for the gulls than facing off with adult terns protecting their nests. Also, the unusually hot summer temperatures combined with any lower level disturbance that flushed brooding adults from nests may have overheated some eggs. Without information from closer monitoring, it is not possible to know exactly what factors, or combination of factors, caused the colony to fail this year. Particularly, we cannot know with certainty whether viable nests and eggs were present or absent when the grading and gravel operations began.