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Home , Guanay cormorant, Kelp gull, List of birds of Peru, Peruvian tern

SEASONAL CHANGES IN THE SEABIRD FAUNA OF

DAVID C. DUPFY Charles Darwin Research Station, Isla Santa Cruz, Galapagos Received 7 January I 98U

i. INTRODCCTION kph while the smaller boat traveled no faster than Relatively little is known of st:asonal changes 10 kph. Trips lasted between three and four in the seabird community of the Peruvian Coastal hours depending on the direction of travel and or Humboldt Current along the west coast of ves~el. South America although extensive field work has During all transects and most seawalchc:;, been done (e.g. Murphy IYJ6, Tovar i%13, scaswell was approximately one-two meters, llughcs 1970, King 1974). This paper summarizes winds were usually southerly, from 0 to 20 kph, ';ix months of observatiPn, using daLa from tran­ and visibility ranged from 200m to 30 km but was sects and a "~eawatch" from a guano island. usually 15 km. The surface water was cdightly ! made daily watches for passing seabtrds from cooler than normal (Table l) with no indication Isla M azorca ( l I 0 2J'S, 77°45'W) Dt:partamento de Lima, Peru from 26 September 1977 to 29 Table l. Comparison of surface sea-water temperatures dur­ March 1978. I was absent from the island on 4-6 ing the study period with temperatures during the warm-water r·:J Niiio phenomenon (Vogt 1942) and with mcnn tempera­ October, 1-4 November, 13-19 November, :-- tures between 192g and 1969(Zuta& Urquizo 1972) 5 December, 29 December-2 January, 1-6 ------Month M awrca: 1977-1978 El Ni1io i\lean February. and 3-7 !\larch. There were three ob­ servation periods daily of twenty minutes each Scp!.einber 15.J"C i 5.8"( during the periods: 0600-0i:J\)0, l000-1300, and Oclilbcr I 5.6 1(,,9 I (>.J ! 600- i 700 hours. Observations were n1ade NuvcnJbcr 16.9 17.5 17.0 iooking north toward the Salinas Peninsula, 15 December 13.0 19.5 17.7 January 2 I. I l'J.l km distant. The field of view wa:; 180° from a February 18.9 21.5 20.4 platform appr1lximately 20m above the sea. M nst ld:11ch IX.(, l'! .'I 21U wt:re observed well within an estimated ki­ lnmeter or the island. l excluded from my CC'Unts or the warm-water El Nino phenomenon. Seabird the nesting on l\Jazorca: Humboldt numbers were much lower later in 1978 (June Pcngu ill Spheniscus humboldti, Peruvian Brown and July) than normal Cf. Parker & R. Ridgely, Pelecanus occidemalis thatzus, Peruvian pers. cornm.). ,')u/a rariegata, Guanay Phala­ Data from the transects are presented in .Table crocura.-..: buugainviliii, Red-legged Cormorant 2 .. For the more common species on the sea­ ff;a/acrocora.\ gaimardi, and Inca Larustema watch, the records are summarized in five-day inca. means and rrescnlcd in Pig. 1-4. Recl'rds of ln addition to the daily watch, I made obser­ less common species are includell in the species' vations on trips between !'vi azorca and the port of accounts and refer to single birds unless !iuacho, 33 km northeast of the island, on 7 Oc­ otherwise noted. toocr; S, J 2, 30 November; 6 and 28 December; 3 and 3 I January; 7 February; aml 2, 8 and 31 2. RESULTS March. Two types of crart were used: a launch of ll•e Barracuda class, approximately 20 m in l. Waved Diomedia irrorata. Al­ !englh with an observation height of 2m, and a 5 though not uncommon on transects, I saw this ,.,, fishing boat with an eicvatio11 of one meter. species from Mazorca only on 27,29 January and Tile launch hau a speed of approximately 15-20 29 MarciL Giant Fulmar Macronectes giganteus. Ardcal>'i(l'JHI): 10'! -IIJ •

110 SEASONAL CHANGES SEABIRD FAUNA PERU [Ardea 69

Table 2. Species seen on transect: Mazorca to Huacho 7 Oct 5 Nov 12Nov 30Nov 6 Dec 28 Dec 3 Jan 31Jan 7 Feb 2 Mar 8 Mar 30 Mar 52 23 32 7 15 2 Cape 2 Pnk-ftcd Shwater 2 Sooty Shwater 40 10000 2025 50000 26 9 7 625 42 5 unid. Shwater 53 8 2 Wilsons st-p 50 3 unid. st-p 3 33 P. diving-p. 15 30 39 7 15 12 2 3 Blue-ft Booby 2 I 10 Chilean I I 13 8 6 2 2 2 l 2 l jaeger spp. 10 20 21 8 6 14 l 10 Franklin's 50 1000 200 1000 200 90 211 14 127 151 !84 Gray Gull 2 6 200 520 -tied Gull I Sabine's Gull I B-tailed Gull 2 6 19 10 3 I I 15 3 3 7 2 2 17 4 2 16 4 2 Sterna spp. 3 30 1000 7 26 8 4 69 25

taxa 13 8 8 3 6 10 8 14 10 II 8 13

Mazorca, 17 December. Ful­ .___. SOOTY AND UNIDENTIFIED marus glacialoides, Mazorca, 27 September. Cape DARK SHEARWATERS Petrel Daption capensis. Mazorca, 27 September; 0-- {) ARCTIC AND UNIDENTIFIED 2, 9, II October. On transects, 7 October. 2. White-chinned Petrel Procellaria aequinoc­ tialis. M azorca, 17 and 20 October. Identified by 2 0 10 I I I white chins seen at approximately 00-150 m. ~ Pink-fooled Shearwater P1@nus creatopus. M a­ <:{ II zorca, 14 October (4); 22 October (6); 24 Oc­ ::z I II X I rl <:{ tober; and 6 November (6). On transects, 2 I II ::z I 'I March (2). Puffinus griseus. Fig. 10 I II >- I I I shows the fluctuations of this species and un­ ..J I ,, I I I <:{ 0 I identified dark shearwaters passing Mazorca over 0 I \\ I I ~I the six months of the observation period: Birds LL. I I I 0 I I o I peaked in October-November and again in I U) I I I I March. Sooty Shearwaters were still seen on z 6 I <:{ I 0 transects from December to February, suggesting w I 0 ::z ,0 I that such summer "residents" presumably non­ 0 I breeders avoided the island in contrast to mi­ grants which frequently passed close by. 0 1 3. Wilson's Storm-petrel Oceanites oceanicus. · 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 OCT NOV DEC JAN FEB MAR Mazorca, 25 November. On transects, only on 30 November (50) and 6 December (3). Distin­ Fig. I. Five day means of daily maxima: Sooty and uniden­ tified dark shcarwatcrs and Arctic and unidentified terns. M a­ guished at close range on 25 November and 6 De­ zorca sea watch. cember by rounded upper edge of rump patch !98! J SEASONAL CHANGES SEABIRD FAUNA PERU Ill

28 November (2) and 31 January. Fig. 2 shows its 0 I o--o SABINE'S GULL I occurrence on Mazorca; the maximum was 17 on ...... _.. BLUE-FOOTED <( 5 I I 24 November. 0 I BOOBY ~ ~ II I 8. Magnificent Frigate- Fregate magnif­ X I <( I NlI I ~ I icens. One immature was mobbed by Inca Terns I I I I I I just off Mazorca on 20 December. It was distin­ >- I I ....1 I I 'I :.;: I I I guished from the Great Frigate-bird F. minor by 0 I I I I I I the absence of rusty coloration on the head and I IJ.. I : I 0 I I I neck (Alexander 1928, Harris 1974). Northern I I I (/) I I Lobipes lobatus. Mazorca, 1 October z I I <( I I w I! 'I I and 25 November. Transects, 5 November (10) ~ 0.1 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 and 6 December. OCT NOV DEC JAN FEB MAR 9. Great Skua Catharacta chilensis. Single birds on transects in January and March. Fig. 2. Five day means of daily maxima: Blue-footed Booby and Sabine's Gull. Mazorca seawatch. I 0. Pomarine Jaeger Stercorarius pomarinus. On transects from the end of December to March. and by dark belly. The group of 50 on 30 No­ II. Franklin's Gull pipixcan. This species vember seemed all to be of this species. They arrived in early November (Fig. 3) but was never were in the middle of a dense aggregation of common at Mazorca except on 12, 13 March feeding Peruvian and Guanay Cormo­ when I ,000 and 300 rafted around the island. rants. Observation was difficult and I may have reidentified the same individuals several times.

4. Sooty Storm-petrel Oceanodromus markhami. -GRAY GULL An individual, presumed to be this species, was 0--0 FRANKLIN'S GULL seen from M azorca on 2 October. Crossin ( 1974) 1 doubts that this species can be separated from II the Black Storm-petrel Oceanodroma me/ania in id II II the field. My identification rests primarily on II <( Murphy's (1936: 747) characterization of :::;: I II I' X markhami as associated with cool, upwelled <( II :::;: Q I I waters while melania is found in warmer waters. I I .... to 1 I 5. Ringed Storm-petrel Oceanodroma hornbyi. >-_J 10 II I <( II I Mazorca, 9 and I I October. Unidentified storm­ 0 II 0 petrel Hydrobatidae spp. Mazorca, I 0 and 17 Oc­ LL. I II I 0 I I 9 tober, and 19 March. On transects, 7 October (3) I I I (/) 01 I ? I I I I and 28 December (33). z I I <( I 9.o, ~ I I ~ w I •P I I I 6. Peruvian Diving-petrel Pe/ecanoides garnotii. :::;: 0 0 \I "'0 I I ol II ,, ,,o 9 I I u M azorca, 13 February; regularly on transects. 0 0 I II 0 0 I 0 There is some confusion over whether this I I p I species nests on M azorca. Tovar (I 968: 529) cites 0 Mazorca on the basis of a personal commu­ nication from R. Jordan. Dr. Jord&n did not O.I30ID2030ID20~ID2030ID2030ID20~ID2030 recall any breeding on Mazorca when I discussed OCT NOV DEC JAN FEB MAR this with him in I 977. Certainly the on Fig 3. Five day means of daily maxima: Gray Gull and Frank­ Mazorca is quite different from that at other lin's Gull. Mazorca sea watch. breeding locations (e.g. Murphy 1925, Tovar 1968). 12. Gray Gull Larus modestus. This species was 7. llluc-foo!cd Boohy Sula nchouxi. Transects, common on transects and around Mazorca until 112 SEASONAl. CHANGES SEABIRD f-AUNA PERU [Ardea 69

early December when it apparently migrated ceding species, this was seen only close to the south to its Chilean breeding grounds (Howell et shore, often feeding on En­ a!. 1974). Individuals began reappearing in graulis ringens from November to March. March (Fig. 3). 20. Sterna hirundo. One indi­ 13. Swallow-tailed Gull Larus (Creagrus) fur­ vidual in non-breeding fish'ed around catus. One transect record on 7 October. and roosted on Mazorca on 28-29 September, al­ 14. Sabine's Gull Larus (Xema) sabini. Single lowing close inspection. individuals or small flocks passed Mazorca, head­ 21. Arctic Tern Sterna paradisaea. Small flocks ing south until mid-November (Fig. 2). On tran­ of terns passed by M azorca in October and sects, 7 October and 12 November. March. When they were close enough to identify, 15. Band-tailed Gull Larus belcheri. This they proved to be this species (Fig. 1). The distri­ species was common around Mazorca (Fig. 4), butions and ecologies of terns wintering along the feeding on the regurgitated pellets of Guany Peruvian coast need study. and on the deserted eggs and young 22. Peruvian Tern Sterna lorata. This is gen­ of the nesting species. It was rare on transects erally an inshore or lagoon species (M. Plenge, except within a kilometer of land. pers. comm.) but I saw it twice on transects, feed­ 16. Kelp Gull Larus dominicanus. Like the ing with other terns Sterna spp. on anchoveta Band-tailed Gull, this species was found in small about 5 km from shore. numbers scavenging in the guano at Mazorca or close to land on transects (Fig. 4). 3. DISCUSSION There were 28 identifiable species; 21 seen on

-- BAND-TAILED GULL the seawatch from Mazorca and 20 during tran­ 0- --o KELP GULL sects. The two methods had 13 species in common. Five of the seven seen from Mazorca but not on transects were . All - \ I b I _J 0 \b-o \ I II waters and storm- while the transects \ 0

30 10 20 30 10 20 31 10 20 30 10 20 30 10 20 30 10 20 30 and February. Such a decrease farther inshore OCT NOV DEC JAN FEB MAR may have been masked by the arrival of northern Fig. 4. Five day means of daily maxima: Band-tailed and Kelp larids and jaegers. . Mazorca sea watch. Several of the species have been presumed to be more characteristic of warmer waters (Mag­ 17. Rynchops niger cinerescens. nificent Frigate-bird) or waters at the edges of Mazorca, 23 October (4), 8 November, and 9 upwelling (Waved Albatross and Blue-footed January (2). Booby; Murphy 1936: 534-35; Nelson 1978). 18. Sandwich Tern Sterna sandvicensis. This While the frigate-bird is probably accidental at species was seen only on transects, from January Mazorca, the numerous records of the albatross to March, within 5 km of the coast. and booby suggest that they occur regurlarly in at 19. Elegant Tern Sterna elegans. Like the pre- least the northern portion of the Peruvian 1981 J SEASONAL CHANGES SEABIRD FAUNA PERU IIJ

Coastal Current. On the other hand, it is possible Crossin, R. S. 1974. The Storm Petrels, pp. 154-205. In: W. B. King (ed.). Pelagic studies of seabirds in the that Mazorca is in an unusual position since there central and easlerns Pacific Ocean. Smithsonian is a tongue of warm water which extends into the Contr. Zoo!. 158. cooler waters of the current west of Mazorca Cushing, D. H. 1971. Upwelling and the production of fish. Adv. mar. Bioi. 9: 255-334. (Zuta & Urquizo 1972: 474, 503). This may serve Guillen, 0. El sistema de Ia corrientc peruana. parte I. as­ as a funnel for warm-water species. pectos fisicos. F.A.O. lnformes de Pesca No. 185: An upwetling is a complex and extensive 243-284. Harris, M. 1974. A field guide to the birds of the Galapagos. mixture of currents and eddies of different tem­ Collins. London. peratures and productivities (Cushing 1971, Howell, H. R., B. Araya & W. R. Millie. 1974. Breeding bi­ Guillen 1976). The present study covered only a ology of the Gray Gull. Univ. Calif. Puhl. Zoo!. 104: 57 pp. small area, close to shore. Further work might llughcs, R. A. 1970. Notes on the birds of the Mollendo Dis­ profitably include regular transects out from the trict, southwest Peru. 112: 229-241. coast, across the entire upwelling, in coordi­ King, W. B. 1974. (ed.) Pelagic studies of seabirds in the central and eastern Pacific Ocean. Smithsonian nation with oceanographic research. In addition, Contr. Zool. 158: 277 pp. El Nino cessation of upwelling and subsequent Murphy, R. C. 1925. Bird Islands of Peru. Putnam's. New southward invasion of warm water offer a York. -- 1936. Oceanic Birds of South America. MacMillan. valuable, natural perturbation experiment. New York. Nelson, J. B. 1978. The . Oxford Univ. Press. Oxford. 4. ACKNOWLEDGMENTS Tovar, H. 1968. Areas de reproduccion y distribucion de las aves marinas en el litoral peruano. Bol. lnstit. Mar I am grateful to PESCA PERU for permission Peru-Callao I (I 0): 525-546. to work on Mazorca and for providing transpor­ Vogt, E. 1942. Aves Guaneras. Bol. Comp. Admora. Guano 1: 1-132. tation. This report was funded as part of a larger Zuta, S. & W. Urquiza. 1972. Temperature promedio de Ia su­ investigation of guano birds by The Organization perficie del mar frente a Ia costa peruana. periodo of American States, Proncetown University, and 1928-1969. Bol. InstiL Mar Peru-Callao 2 (8): 459-520. The National Science Foundation of the United States (Grant DEB-7716077). I appreciate their support. David Cameron Duffy.

5. REFERENCES Department of , Princeton University, Princeton, New Yersey, 08544, U.S.A.; current address: The Charles Alexander, W. B. 1928. Birds of the Ocean. Putnam's. New Darwin Research Station, Isla Santa Cruz, Galapagos Islands, York. .

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