nirber in the last column gives the atlas identification number (1977 data). 

 A "0" means that the colony was not occupied in 1977. 



1977 FIELD DATA 



All 1977 nesting data are listed by species and colony for each State. 

 The third column gives the date of the inventory (month, day, year). The 

 fourth column lists the number of nesting pairs estimated. A code of "800000" 

 indicates "possible" nesting. The fifth column indicates the inventory 

 method: "AD-EST" (adult estimate - air or ground); "NEST-CT" (nest count); 

 "NEST-ES-SP" (nest estimate from sample count); "PHOTO-CT" (count from photo- 

 graphs); etc. "Other" refers to a combination of methods. The last column 

 lists the major observer for each inventory. Whereas the atlas lists only the 

 "best estimate" for each species at a colony, this listing includes all the 

 estimates made. 



1976 FIELD DATA 



The 1976 data is ordered first by colony, listing all species and corre- 

 sponding nesting pair estimates. Habitat and nest site substrate are listed 

 in abbreviated form and census date is given as before. The census (inven- 

 tory) techniques are coded differently from 1977; "TOT-CT-ADU" (=total count 

 of adults) corresponds to "AD-EST" in 1977. "F-W-AIR-ES" (air estimate with 

 fixed-wing aircraft) corresponds to "AD-EST-AIR in 1977. In 1977, both fixed- 

 wing and helicopter aerial estimates are combined. The remainder are self- 

 explanatory. Lastly, time and observers are listed. 



HISTORICAL DATA 



The historical (19C0-1975) data are ordered by species (in A.O.U. number 

 order) and year, beginning with the earliest records. When species in mixed 

 colonies were not estimated separately, the general categories "terns", 

 "gulls", and "herons" are used. When a range of years is given (e.g. 1940- 

 1950) by an author, a "1999" year code is given, and the year range is given 

 under the "observation" column. Nesting pair estimates are given. A code of 

 "800000" indicates "possible" nesting; "900000" means definite nesting, but no 

 numbers are provided. Much confusion arises in the literature in differen- 

 tiating "pairs" and "bird" estimates. If only adult totals were given, the 

 following factors were used to convert adult numbers to breeding pairs: X 1.0 

 for all gulls, cormorants, and wading birds; X 0.80 for terns; X 0.50 for 

 black skimmers. When reference to a "few" pairs of a species was made, an 

 entry of five pairs was used. The "observation" column simply lists addi- 

 tional pertinent information about the species or inventory methods used at 

 that colony. At least one reference for each data entry is shown. Limited 

 space precluded all references from being listed. Since much of the data was 

 derived from the field notes sections of various ornithological journals, only 

 the journal name is given, not the name of the editor or year. Abbreviations 

 are used throughout and are shown in Table B3. 



In Maryland and Virginia, the historical data is separated into two 

 regions, Chesapeake Bay and the Atlantic coast (eastern shore). 



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