Column headings:
A: _Pluvialis dominica_
B: _Charadrius mongolus_
C: _Numenius phaeopus_
D: _Actitis hypoleucos_
E: _Heteroscelus_ spp.
F: _Heteroscelus incanus_[+]
G: _Heteroscelus brevipes_[+]
H: _Limosa lapponica_
I: _Arenaria interpres_
J: Unidentified
K: Total No. of individuals
L: Total No. of species
=============+====+====+====+====+====+====+====+====+====+====+====+====
| A | B | C | D | E | F | G | H | I | J | K | L
-------------+----+----+----+----+----+----+----+----+----+----+----+----
March 11 | x | | | | | | | | | | x | 1
March 17 | 10 | | 1 | | 2 | | | | | | 13 | 3
March 19 | x | | x | | x | | | | x | | x | 5
April 24 | x | | | | | | | | | | x | 1
April 26 | | | | | | | | 1 | | | 1 | 1
May 19 | | | | | 3 | 2 | | | | | 5 | 1
May 21 | | | | | 4 | | | | | | 4 | 1
May 26 | | | | | x | 2 | | | | | x | 1
June 1 | | | 1 | | | | | | | | 1 | 1
June 6* | | 1 | x | | x | | 1 | | | x | x | 4
June 11 | | | 1 | | | | | | | | 1 | 1
June 12 | | | 12 | | 2 | | | | | | 14 | 2
June 22 | | | 2 | | | | | | | 1 | 3 | 2
June 30 | | | | | | | | | | 2 | 2 | 1
July 7 | | | 2 | | | | | | | | 2 | 1
July 8 | 3 | | x | | 1 | | | | | | x | 3
July 16* | 6 | | 3 | 3 | 4 | | 1 | | | | 17 | 4
July 19 | x | | x | | x | | | | | | x | 3
July 24* | 10 | | 6 | | 3 | | 2 | | 3 | 5 | 29 | 5
July 26 | | | 8 | | | | | | | | 8 | 1
August 2 | | | x | | | | | | | x | x | 2
August 3 | | | 1 | | | | | | | | 1 | 1
August 6* | | | 6 | | 12 | | | | | | 18 | 2
September 29 | x | | x | | | | | | x | | x | 2
October 3* | x | | | | x | | | | | | x | 2
October 10 | x | | x | | x | 2 | | | x | | x | 4
October 11 | | | | | | | | | 2 | | 2 | 1
October 23* | x | | x | | x | 1 | 1 | | x | | x | 5
October 24 | x | | | | | | | | | | x | 1
-------------+----+----+----+----+----+----+----+----+----+----+----+----
x Observed but numbers not recorded.
* Observations made on beach at Agfayan Bay area.
[+] Figures based on identified skins.
None of the above workers, however, obtained very much information on
comparative numbers of species.
Tables 8, 9, and 10 present the writer's findings on populations of
migratory shore birds in Micronesia in 1945. At Guam, as shown in table
8, the records for March, April and early May are few, owing to a
limited amount of field observation. Beginning in late May and until
October 24 a greater amount of time was spent in the field and more
regular records were obtained. No observations were made by the author
at Guam in the period from August 11 to September 25. The dates marked
with an asterisk are those on which observations were made on the
extensive tidal flats at Agfayan Bay and vicinity. These flats, at low
tide, present excellent feeding grounds for waders and in 1945 were
undisturbed by parties of service personnel, because the area was
"off-limits."
Table 8 shows that _Pluvialis dominica_, _Numenius phaeopus_, and
_Heteroscelus_ spp. were the shore birds most frequently found at Guam
in this period. _Pluvialis dominica_ was the most numerous of the three
species. Of _Heteroscelus_ there was approximately equal representation
of _H. incanus_ and _H. brevipes_ as indicated by specimens collected.
These birds were not identified to species in the field.
Although records were made only infrequently in the spring migration,
such information as was obtained indicates that the populations were
largest in March and early April. On April 24, _Pluvialis dominica_ was
the only bird observed on beaches and in upland openings. On April 26, a
single _Limosa lapponica_ was recorded. On May 15, no shore bird was
seen on a trip along several beaches. In late May and early June, single
individuals of _Heteroscelus_ were found. Of this genus, those collected
in May were in nuptial plumage, and those collected in June were in
winter plumage and probably should be classed as non-migrants. _Numenius
phaeopus_ was occasionally recorded beginning in early June, but waders
were totally absent from beaches at Agfayan Bay and vicinity on June 18
and 19. Few shore birds were seen in early August. In late September,
birds, especially _Pluvialis dominica_, _Numenius phaeopus_, and
_Heteroscelus_ spp., were numerous. These species were numerous until
October 24, when observations were discontinued.
Of the 17 species of migratory shore birds recorded from the Mariana
Islands, eight were identified. Of these eight, three species, _Limosa
lapponica_, _Actitis hypoleucos_, and _Charadrius mongolus_, were found
on only one occasion. Never more than four species were identified on a
single field trip. These data give an idea of the lack of variety of
species that may be observed on Micronesian islands.