Short Communications 
The Wilson Journal of Ornithology 124( 1): 152-157. 2012 
Food Habits of Two Fork-tailed Swifts in Venezuela 
Charles T. Collins 1,2 and Betsy Trent Thomas' 
ABSTRACT.—The aerial arthropod prey of Neo¬ 
tropical Palm Swifts ( Tachomis squamata) and Lesser 
Swallow-tailed Swifts ( Panyptila cayennensis) in Ven¬ 
ezuela included seven Orders and 60 families of insects 
plus spiders and mites. Diptera were the most numerous 
prey (>50%) taken by both swifts. Prey size ranged 
from 0.5 to 7.9 mm and averaged 2.43 and 2.77 mm. 
respectively. Both prey type and foraging habitat 
differences of these swills could be interpreted as 
mechanisms for resource partitioning. Received ( 
March 2011. Ac cepted 20 September 2011. 
The tails of birds are diverse in both morphology 
and function. The size and shape of most tails 
reflect their functional aerodynamic properties, bul 
many others are highly modified for use in sexual 
displays (Thomas 1997). Deeply forked tails are 
found in many species including some swifts 
(Apodidae). swallows (Hirundinidae), and terns 
(Steminae) and may reflect selection for both 
aerodynamic and display functions. Forked tails 
are thought to provide additional lift, when fanned, 
and increased turning agility (Thomas 1997). 
Deeply forked tails in aerial foraging inseelivores 
may be adaptations for pursuit and capture of more 
agile prey or foraging low to the ground and close 
to vegetation (Waugh and Hails 1983). Fanning of 
the wing and tail feathers is a frequently observed 
behavior associated with rapid flight changes 
during prey captures by swiftlets (Manchi and 
Sankaran 2010). Differences in prey selection 
resulting from variable flight behaviors may be 
an important isolating mechanism for closely 
related species, particularly when in mixed species 
foraging flocks (Waugh and Hails 1983). 
It is usually difficult to get detailed information 
on the prey taken by aerial foraging inseelivores 
(Jahn et al. 2010). Direct observation can only detect 
or identify larger prey items and remains of smaller 
1 Depanment of Biological Sciences. Qdilbmia Stale Ur 
CA lJ SA: email: ccdgmOc^ 
CA^ZT.vTr' Fairbr ” k *«• B, 
3 Deceased. 
and more delicate prey may be undetected in gut 
contents or fecal samples. The boluses of arthropod 
material collected by swifts allow detailed analysis 
of both the prey taxon anti prey size of even small 
insects and spiders. However, this infonnation is 
only available during the chick-rearing period of the 
breeding season and may not be representative of 
swift diets at all times of the year. Prey type and 
availability may change substantially during the 
drier non-breeding season in tropical regions (Hails 
and Amimidin 1981, Jahn et al. 2010). 
The goals of our study wore to: (I) describe the 
type and size of the prey taken by two neotropical 
swifts having deeply forked tails, the Neotropical 
Palm Swift {'Tachomis squamata) and the Lesser 
Swallow-tailed Swift (Panyptila cayennensis ); 
and (2) look for qualitative differences in prey 
taken by other swifts lacking deeply forked tails. 
The Neotropical Palm Swift is a widespread 
and common resident of lowland sandy soil or wet 
savannas throughout its range extending from 
eastern Colombia and Venezuela south to eastern 
Peru, and Amazonian Brazil (Hilty and Brown 
1986. Hilty 2003). it is usually observed circling 
al “low to moderate heights” over open areas 
where there are palms (Hilty 2003:389). h less 
commonly occurs in urban areas where palms 
have been planted (Chanlier 2000. this study). 
The Lesser Swallow-tailed Swift occurs troin 
southern Mexico south to southeastern Peru, 
northern Bolivia, and Amazonian and southeastern 
Brazil (Hilty and Brown 1986. Sick 1993. Howell 
and Webb 1995, Hilty 2003). It is “uncommonand 
local in occurrence ... over humid lowland and 
foothill forest or partially forested terain (Hilty 
2003:389) at elevations of 1.000 to 1.400 m (Hilty 
and Brown 1986. Stiles and Skutch 1989. Hilt) 
2003). Its characteristic tubular nests occur at 
elevations from <100 to >800 m in Trinidad and 
Venezuela (pers. obs.), and in urban areas in 
Surinam (Haverschmidt 1958). 
METHODS 
Food samples of the two species ol swifts were 
collected as boluses of food being brought to 
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