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 Sept., 1909 151 THE NESTING OF THE HEERMANN GULL By PINGREE I. OSBURN xVITH 'I',VO I'HOTO,'4 N the spring of 1909, it vas my privilege to be one of a party to make acruise down the west coast of Mexico in search of interesting forms of bird and animal life. The primary object of my trip was to discover, if possible, the nesting place of the Heermann Gull (Larus heermanni). Every year these birds have migrated south in the spring and were generally supposed to breed somewhere in the Gulf of Lower California. After a sea voyage of over 1500 miles (from San Diego, California) they were located breeding on a remote rock of[ the coast of the State of Jalisco, Mexico, in about the parallel 18 N. Prior to the time of the visit of our party little or nothing was known of the habits of these birds in their breeding grounds, and the observations taken in this colony have brought to light many facts. NESTING GROUNDS OF THE HEERMANN GULLi ISLANDS OFF COAST OF JALISCO, MEXICO NO Heermann Gulls were seen on the trip until found at their breeding grounds, nor were any noted flying about at any distance from the nests on the rock, which would indicate that they do not wander away from their colony in the nesting time, as do the Western Gulls (Larus occidenlalis). When approaching a colony of Western Gulls its nearness is evidenced by occasional individuals sailing about for miles on all sides of their nesting grounds. Not so with Larus heermanni. They were not seen farther than one-half mile from the colony. Possibly this is one reason why their nesting grounds are easily overlookt. This fact was imprest upon me clearly while getting acquainted with the species in its native haunts. We were anchored two days near the nesting rock before the first bird 'was seen. My first glimpse of the birds was when an adult flew near enough to our schooner for identification, and I at once determined to make an effort to find more; for what was an adult doing in these waters at the hight of nesting time, April 107 The next morning (April 11)I noted a few flying about over a low fiat rock a little distance from our anchorage. It was here that I first found them breeding