128 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
TABLE 1. Size and mass (x ± SD) of Burmese pythons that were feeding on birds and collected in Everglades National 
Park, Florida, USA (2003-2008). Range data for all measurements are estimated to the nearest decimal point. 
n Total length (cm) n Snout-vent length (cm) n Mass (g) 
Male 37 231.8 ± 52.6; range 91-325 37 202.1 ± 45.7; range 80-286 36 6,415 ± 3,524; range 990-17,054 
Female 44 276.0 ± 72.4; range 114-475 44 243.7 ± 65.2; range 99-424 42 12,158 ± 11,778; range 490-56,690 
Totals 81 255.8 ± 67.4; range 91—475 81 224.7 ± 60.5; range 80-424 78 9,508 ± 9,371; range 490-56,690 
and Laybourne 1985) when ample material is 
available. Python gut samples were first sorted 
and cleaned following methods used by Sabo and 
Laybourne (1994) for dry pellets. Many of these 
samples were wet or frozen and often odoriferous. 
Thus, we worked in a fume hood to sort and 
conduct initial cleaning. Species identification 
methods used depended on the type, quality, and 
quantity of material, and on the extent of digestion 
of each sample. Large items of whole feathers, 
feather fragments, or partial bones were sub¬ 
sampled and cleaned separately. This reduced the 
amount of time in the cleaning process and left 
some material with the original sample for future 
analysis of other food items. 
Microscope slides were made from downy 
feather barbules in gut samples following Dove 
et al. (2005) for fragmentary evidence. The 
leather identification technique involved examin¬ 
ing the vaiiation in the microscopic characters of 
the plumulaceous (downy) barbs and comparison 
of whole feathers or large pieces of feathers to 
museum study skins stored in the Division of 
Birds, National Museum of Natural History. 
Microscopic identifications were primarily used 
to identify the material to taxonomic Order or 
Family (i.e., Rallidae, Anatidae) of each sample, 
and then in combination with other feather 
fragments, osteological material, geographic lo¬ 
cation, and circumstantial evidence associated 
with the sample to corroborate species identifica¬ 
tions. We counted samples that contained more 
than one species of bird (e.g., sample #128; 
Anatidae and Anhingidae) accordingly but were 
unable to ascertain if more than one individual of 
the same species was consumed in heavily 
digested samples. We used measurements of 
~260 cm TL for females and >200 cm TL for 
males provided by Reed and Rodda (2009), to 
ascertain if pythons were mature. 
RESULTS 
Gender, length, and mass were available for 
most pythons examined. The ratio of males to 
females was nearly equal (37 males, 44 females). 
Males were smaller than females in both mass and 
body measurements (Table 1). Sixty-eight of the 
85 Burmese pythons in this study were ascer¬ 
tained to be mature based on measurements. 
Burmese pythons were collected throughout ENP 
during every month of the year with most being 
collected in December and January. 
We identified 25 species of birds representing 
nine avian Orders from the 85 Bumiese pythons 
(Table 2). Eighty-nine individual birds were re¬ 
corded including 54 that were identified to species 
level, one identified to Order, 18 identified to 
Family, and 16 that were identified only as Aves 
(bird), due to lack of diagnostic feather material. 
Gruiformes (rails and allies) were the most 
numerous bird prey of Bumiese pythons and 
represented eight species and 32 individuals (36% 
of birds consumed). Ciconiiformes (herons and 
bitterns) were also common in the samples (18%) 
and included six of the 13 species occurring in 
Florida. Pied-billed Grebe (Podilymbus podiceps ), 
White Ibis ( Eudocimus albus ), and Limpkin 
(Ararnus guarauna) were the species most com¬ 
monly identified, each occurring in seven differ¬ 
ent python samples. The most interesting prey 
item encountered was a Magnificent Frigatebird 
(Fre gat a magnificens; sample #744) collected 
~50 km from a known roosting area for frigate- 
birds (R. W. Snow, pers. obs.). Domestic Chicken 
(Gallus gallus domesticus) was found in two 
separate samples and Domestic Duck (Anas 
platyrhynchos domesticus) in one sample col¬ 
lected near agricultural areas that abut the park. 
Four species identified, Little Blue Heron (Egretta 
ccierulea), Snowy Egret (E. thula ), White Ibis, and 
Limpkin are considered species of special concern 
by the Florida Fish and Wildlife Conservation 
Commission (Gruver 2010) and a fifth, the Wood 
Stork (Mycteria americana), is listed as federally 
endangered (Federal Register: 27 September 
2006, Volume 71, Number 187). We found no 
evidence of eggs or chicks in any of the python 
samples examined. 
