Adult tern fishing photo courtesy of Andrew Beierly

Adult tern fishing photo courtesy of Andrew Beierly

Arctic Terns that make an annual migration to Skagway are getting some help from their non-feathered friends—the Skagway Bird Club (SBC). The SBC recently published a report of breeding pairs and the challenges they face. The following is a portion of the report:

The Skagway Bird Club (SBC) created a citizen science-monitoring project designed to gather information about a small Arctic Tern breeding colony on the Ore Dock Peninsula in Skagway, Alaska. Terns were observed in the colony area from April 23 to July 27, 2016. Breeding adults were estimated to number about 30 to 40 (about 15 to 20 pairs). High counts of roughly 60 to 80 terns were recorded during the peak of the breeding season. Breeding terns nested in areas used by three commercial businesses. Tern scrapes (nests) were seen on both gravelly and hard surfaces. Terns preferred relatively level and open sites among minimal-profile structure (small rocks, wood, low vegetation, small changes in ground surface), near low structure (chainlink fence, concrete barrier, higher or thicker vegetation) and without flight obstructions on at least one side.
Part of the colony accomplished reproduction in a short time period (2 months), indicating favorable conditions and low stress. Part of the colony required longer time periods (up to 3 months), which is associated with disturbances affecting the maturation process. Some breeding adults displayed mating behaviors mid-season, pointing to early failure or destruction of some scrapes or chicks.
Skagway’s breeding terns were very tolerant of many kinds of frequent, predictable human disturbances. The terns reacted negatively to unusual and unpredictable human disturbances. Stationary objects (plastic owls, traffic cones) did not affect the terns. Terns sought shelter from harsh environmental conditions such as hot sun or high winds. Colony adults flushed in response to avian predators, while scrape spacing indicated that the colony was largely protected from land predators. Late in the season, internal disturbances were seen: other terns mobbing adults trying to feed chicks, and some adults showing hostile behavior toward late chicks.
Overall, the Ore Peninsula breeding colony was successful in 2016, but development time periods and late mating behavior indicate part of the colony was impacted by disturbances. The colony location is close to the prime fishing site at the mouth of the Skagway River. Human activities likely have a negative effect upon some terns, while at the same time evidence points to human disturbances providing a refuge from land predators for the colony.

History of terns in the area
Arctic Terns have historically used the shores and gravel bars of the lower Skagway River as breeding sites. Over the past half-century, humans narrowed and diked the lower river, and created an artificial Ore Dock Peninsula near the river mouth. Breeding terns moved to the peninsula, where they now reproduce surrounded by a high level of human disturbance from commercial business operations. Some tern nests and chicks are easily seen from the peninsula access road and have become a popular attraction for birders and tourists.
In June 2015, two unusual and severe human disturbances occurred at the known breeding colony at about the same time that birders noticed that terns abandoned the site. In July 2015, the Skagway Bird Club published a press release that describes the 2015 situation, summarizes Arctic Tern breeding biology, and presents the limited site-specific information available at the time for the Skagway breeding colony. (Appendix A)
Arctic Terns are protected under the Migratory Bird Treaty Act, which prohibits damaging the nests or young of breeding birds. In August 2015, the municipality of Skagway created a Migratory Bird Working Group to review the Arctic Tern situation and promote protection of all Skagway’s migratory birds. The working group identified a need for better information on Skagway’s breeding terns.

Read the entire report.