Pizo • LEK BEHAVIOR OF THE PLOVERCREST 
109 
678 9 10 11 12 13 14 15 16 17 18 
Hour 
6 7 8 9 10 11 12 13 14 15 16 17 18 
(3) (2) (2) (4) (3) (4) (1) (1) (4) (7) (5) (2) (1) 
Hour 
FIG. 2. Daily activity at the Plovercrest lek: (A) lek 
attendance, and (B) singing rate. Sample si/.es used to 
calculate singing rates (i.e.. number of I -min periods when 
songs were counted) are in parentheses. Means (small black 
squares), and standard errors (vertical bars) are indicated. 
surveyed. 1 cannot totally eliminate the possibility 
dl detection bias for PI overt' rests, but el torts to 
loca te singing males away from the road margin 
"'ere unsuccessful. The preference for edge 
habitats by hermits has been hypothesized to stem 
lroni three non-exclusive reasons: (I) the high 
"cto levels of edge areas stimulate the growth ol a 
dense understory where males establish singing 
perches; (2) the nearby occurrence of plants 
'plaited by hummingbirds, which facilitate 
feeding by territorial males; and (3) open areas 
provide a convenient flight path tor territorial 
males and visitors (Snow 1974. Stiles and Wolf 
I cannot discard any of the three reasons as 
nfluencing the settlement of Plovercrest leks. For 
instance, although the availability of a dense 
mderstory is likely more important lor hermits, 
'"ose perches used for singing are usually lower 
K - ni) than those used by trochilines (data in 
1 vs. data summarized by Ramjohn cl al. 
' I,,J 3). the height of the perches used for singing 
b > Plovercrest" is among die lowest reported tor 
^hilines (Table 1). An additional reason tor the 
Putative preference for edge habitats, pertaining to 
lr °chilines, could be the importance ol an 
Equate light level for the proper exhibition of 
particular patches in the plumage of displaying 
birds, as demonstrated for other lekking birds 
(Endler 1996). Trochilines, contrasting with the 
usually drab colors of hermits, have iridescent 
patches in the plumage whose full brightness 
depends on the correct light level. One such 
iridescent patch in Plovercrests, the male crest, is 
conspicuously shown in lekking displays. 
The number of male Plovercrests at leks in my 
study (2-7) was within the range reported for 
othcr Trochilinae hummingbirds, which varies 
from two to 20 (Table 1). Territory size and 
distance between neighboring territories, howev¬ 
er. were among the lowest values reported for 
trochilines (Table 1). Lek size in hummingbirds is 
likely influenced by population density, being 
negatively correlated with distance between 
neiuhboring territories (Snow 1973). Territory 
size may also he influenced by vegetation 
structure. Stiles and Wolf (1979) noted the 
smallest territories of Long-tailed Hermits in 
Costa Rica were in very dense thickets, while 
the largest territories were in open forest under- 
story. The density of woody vegetation at the 
main Plovercrest lek was intermediate between a 
dense forest understory and an open field. 
Provided the observation by Stiles and Wolf 
(11)79) can be generalized, Plovercrest leks in 
forest interior should have territories closer to 
each other than reported in my study, 
Seasonal and daily activities at the Plovercrest 
lek in my study resembled those ol other 
hummingbirds. Activity at hummingbird leks is 
either limited to the breeding season (Snow 196S, 
1974), with the exception of Swallow-tailed 
Hummingbirds that are found at leks throughout 
the year (Pizo and Silva 2001), or is greatly 
reduced during the non-breeding season (Stiles 
and Wolf 1979). Lek activities tor Plovercrests 
also coincide with the breeding period (Schuch- 
mann 1999, Belton 2003). 
The daily activity pattern of Plovercrests was 
similar to that described for White-bellied Emer¬ 
alds (Amazilia Candida ; Atwood et al. 1991). and 
Long-tailed Hermits (Stiles and W'olf 1979), 
where males left the lek after a period of high 
singing rate in the early morning. Singing rates 
again increased after this interval, but then 
gradually diminished during the hottest hours of 
the day. The daily activity pattern at hummingbird 
leks as hypothesized by Stiles and Wolf (1979) 
likely reflects the need of displaying males to 
leave the lek area for foraging. 
