•. • -. Artificial and Modified Burrows Establishment for the Atlantic Puffin (Fratercula arctica) on Petit Manan Island, Maine Socheata Lor Biology Department, Ripon College, Ripon, WI 54971 Abstract. An a.ttempt to establish a breeding population of Atlantic puffin colony using artificial and modified burrows on Petit Manan Island resulted in 3 of 17 burrows being used by puffins. Two chicks were presumed fl edged and one egg was laid but eventually disappeared, perhaps preyed upon by gulls or razorbills. Numbers of birds present on and around the colony were greatest in June and August. A temporary decline in July may nave been due to disturbances of the colony. Suggestions for burrow modifications in future projects include construction of completely dry and dark burrows with nesting chambers. Keywords: Atlantic puffin (Fratercula arctica), artificial burrows, Petit Manan Island, construction, eggs, chicks. 2 Of the 22 extant species of alcids (family Alcidae), Atlantic puffins (Fratercula arctica) are one of the commonest alcids in the North Atlantic. Harris ( 1976, 1984) estimated approximately 15 million puffins in the world, the bulk (8-10 million) existing in Iceland. In the United States historical records reveal th at in the mid 1800' s puffins nested on approximately seven islands off the coast of Maine (Kress 1977). As a result of people hunting for food and feathers, puffin populations on all but two islands, Machias Seal Island ( 44°3 0' N: 67°06'W) and Matinicus Rock (43°47'N: 68°51 'W), were extirpated by 1900 (Kress 1977). Fortunately, several years later protective actions were taken to preserve the few birds that persisted on the Maine coast (i.e., Migratory Bird Treaty Act of 191 8, The Lacey Act, and Maine's model Wild Bird Act of 1900). In 1977, S. Kress, under the auspices of the National Audubon Society, started Project Puffin, a re-introduction program of Atlantic puffins to these islands. Presentl y, Machi as Seal Island has the largest puffin colony on the· Maine coast, with an estimated 800-1000 birds (Kress and Nettleship 1988). Until 1984, there have been no records of puffins on Petit Manan Island (PMI). In 1984, immediately after the U.S. Fish & Wild1ife Service poisoned gulls (with DRC-1339, EPA registration #6704-77) on PMI and Green Island, a number of seabird species returned to PMI, and puffins were recorded then for the first time. The first year that a pair of puffins nested and fledged a chick on PMI was 1989. In 1990 a chick was hatched but was washed out of 3 its burrow by a heavy storm (S. Swann, pers. comm.; A. Roberto, pers. comm.). From 1984-1989, M. Drennan and D. Folger modified rock crevices with metal sheets and rocks on the eastern side of the island. Some of these burrows were used by terns and black guillemots (Cepphus grylle), but none was occupied by Atlantic puffins (Roberto, pers. comm.). This paper reports the results of an attempt to establish artificial and modified puffin burrows on PMI m the summer of 1991, and offers suggestions for future projects. Breeding behavior. Puffins breed mainly on deserted, isolated islands. Although some birds have been known to use rock crevices, they generally prefer soil for their burrows, which they are able to excavate with their large beaks and feet. Normally, puffins return to their breeding site in mid-March to early April (Harris 1984, Kress and Nettleship 1988), and in some instances as late as June (Hornung and Harris 1976), but usually one month before egg laying (Ashcroft 1979). Once at the breeding colony, experienced puffins usually claim the same burrow and partner from the past years. Very seldom do puffins excavate new burrows (Harris 1984 ). Often the burrows need to be cleaned or repaired after damage over the winter (Harris 1984, Hornung and Harris 1976, Nettleship and Birkhead 1985, O'Donnell 1989). Puffins that do not have burrows use rock crevices, rabbit holes, or Manx shearwater (P uffinus puffinus) burrows (Harris 1984, Nettleship and Birkhead 1985). The \ bottom of the burrow chamber is usually lined with dry grass, dry seaweed, strings, feathers, sticks, and other vegetation (Harris 1984; 4 pers. obs.), and occasionally with dry sea urchin or clam shells (pers. obs.). Sometimes puffins will lay their eggs on bare rock in the burrow (Nettleship and Birkhead 1985). The age of first breeding in puffins is between 4-6 years (Ashcroft 1979, Harris 1984, Kress and Nettleship 1988, Nettleship and Birkhead 1985). Many 4-year birds occupy burrows but only one third of them are successful in rearing youngs (Harris 1984). The most successful breeders are 5-6 year olds (Ashcroft 1979; Harris 1980, 1983, 1984; Nettleship 1972; Nettleship and Birkhead 1985). Courtship displays and copulation take place at sea, usually close to the breeding colony (Harris 1984, Nettleship 1972, Nettleship and Birkhead 1985). The age of a puffin can be determined by the number of grooves present on the bill, which increases with age (Harris 1979, 1981, 1984; Petersen 1976). Most breeding birds possess 2 or 3 grooves; 4-and 5-year olds have 2 grooves, sometimes with a trace of a third; 3 year olds have 1.5 grooves; 2 year olds mainly have < 1 groove. First-year birds have gray, dusky faces, no distinct grooves on the bill, and poorly developed eye-ornaments. Kress and Nettleship (1988) suggested that inter-colony movement occurs before the first breeding age (4-5 y) but by the time the adults reach age 6 they cease to move because they have established their breeding ground. Thus, Kress and Nettleship concluded that the main function of inter-colony movements is to explore for breeding territory. The roles of the sexes are roughly equal, although males do most of the agonistic territorial defense (Nettleship 1972). This 5 aggressive behavior is usually expressed by gaping, during which the beak is slightly open and the head is angled towards the threatened bird, with the neck feathers erected. Another commonly seen agonistic behavior is fighting, in which two puffins interlock bills and wrestle with wings outstretched, and sometimes scratch the opponent with their claws (Harris 1984). Such incidents can last 5 min or longer, until one bird lets go. Both sexes incubate the single egg and brood the chick (Harris 1984, Nettleship and Birkhead 1985). Kress and Nettleship (1 988) report that birds on Eastern Egg Rock (43°52 'N :69°23 'W) lay eggs around 23 April, and eggs hatch for experienced birds around 8-15 June (6 d later for inexperienced birds). Most adults fledge and depart the island in mid-August. Generally, incubation takes 38-43 d, varying from region to region as modified by weather and food availability (Nettles hip and Birkhead 1985, Harris 1984 ). After hatching the chick takes about 3 d to gain thermoregulation (Kress and Nettleship 1988). It then takes 38-44 d to fl edge (Ashcroft 1979, Harris 1980, Kress 1977, Nettleship 1972, Nettleship and Birkhead 1985). The extreme is 74 d, reported by Nettleship and Birkhead (1985). Young puffins fledge at night, preferably during a dark, misty ni ght when they are out of predators' sight (Harris 1978, 1980, 1984; Hudson 1979; Nettleship and Birkhead 1985). These studies also indicate that chicks usually lose about 10% of their pre­ fledging body weight but attain about 69-80% of the adult weight at fled ging. Both parents are responsible for feeding the single chick. Puffin food consists mainly of fi sh. Kress (1982) reports that 6 Eastern Egg Rock birds feed on herring (Clupea harengus). It is assumed that PMI birds also feed on herring since ·the majority of the fish brought in by terns on PMI are herring. Harris (1984) reports that sandeels (Ammodytes spp), herring, and sprats (Sprattus sprattus) are the most common prey of puffins throughout the eastern Atlantic and the Barents Sea, but in eastern Canada the most important food is capelin (Mo/lotus villosus). Relative to other birds, puffins have one of the highest survival rate. Undisturbed, puffins generally have a very high survival rate. Ashcroft (1979) and Harris (1983) indicate that the adult survival rate on Skomer Island, Wales (51° 44 'N: 5°19'W) and on the Isle of May, Britain, averaged 95%. Ashcroft (1979) also found that 95% of the chicks that hatched survived to fledging. However, Harris found that only 60% of the 95% survived to the third year, and only .3-9%. o! that 95% survived to breeding age. As is usually true of other birds, there is a high mortality rate of young before reaching breeding age. On Eastern Egg Rock, Kress (in Harris 1983) found that 54% of artificially reared chicks reached 2 y of age. Survival rates of 3-4- year-olds on Skomer Island were estimated to be 58-63%, but for older birds it was 88% (Harris 1984). Puffins have been reported to be extremely sensitive to disturbance, particularly by humans. If disturbed during the incubation period, the adults often abandon the egg. However, disturbance after hatching does not seem to have any great effect on the birds (Harris 1983, 1984; Nettleship and Birkhead 1985). Ashcroft ( 1979) found 64% of the pairs in undisturbed areas bred ·I 7 successfully, as opposed to the 41 % in disturbed burrows (study burrows;. Study Site. Petit Manan Island (44o 42' N: 67° 52' W) is a 6.5 ha island located in the Gulf of Maine, approximately 5 km from the nearest mainland (see Fig. 1). It is a treeless national wildlife refuge, dominated by raspberry (Rubus idaeus), iris (Iris versicolor), tall buttercup (Ranunculus acris), and the grass Calamagrostis.