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poles (Pond 1 > 10,000, Pond 2 4,872, and Pond 3 5,684).All cannibalistic encounters occurred in feeding aggregationsin the vicinity of a clutch of conspecific eggs that had hatchedwithin the previous two days or were in the process of hatching.Cannibals were in early feeding stages, 25–27, and preyed on tadpolesin stages 20–25. Prey tadpoles with yolk sacs did not strugglewhile older tadpoles in stages 24–25 lashed their tails, but did notescape. Cannibals seized conspecifics on all body sites, includingthe head, back, abdomen, and tail. Cannibalistic encounters wereinitiated by a tadpole butting into another individual with its snout.Butting was a characteristic behavior engaged in by feeding tadpoles.Cannibalistic tadpoles did not pursue their prey if it movedaway when butted, nor did they remain in the vicinity of newlyhatched tadpoles to selectively hunt and prey on them. Most tadpolesthat butted into newly hatched conspecifics did not seizethem. These non-cannibals were frequently observed resting alongsideor on top of newly hatched tadpoles.Other tadpoles butted the feeding cannibal and some individualsseized part of the prey. Some individual tadpoles fed on theprey for a few minutes before leaving and being replaced by anothertadpole. In 32 instances where the entire cannibalistic encounterfrom initiation to complete consumption was observed,from 1–7 tadpoles consumed part of a single newly hatched tadpole(mean = 2, SD = 1.5).Cannibals were behaviorally and morphologically indistinguishablefrom other tadpoles in the feeding aggregations. However,their cannibalistic feeding behavior was conspicuous because theyjerked sharply from side to side as they engulfed their prey. Groupsof cannibals feeding on one tadpole tugged in opposing directionsand tumbled about in the water, often upside down. In three cases,one individual pulled the prey away from the other tadpoles andrapidly swam away. The other tadpoles pursued a few millimetersbefore stopping to feed elsewhere.In 19 timed observations, a cannibal consumed a tadpole in lessthan 5–2400 sec (mean = 866 sec, SD = 697.7). Large cannibalsconsumed small prey faster than cannibals that consumed preyclose to their size. Some cannibals were the same size (SVL) astheir prey, while others were up to 50% larger. The length of timefor ten groups of two or more cannibals to completely consumethe same prey ranged from 79–1800 sec (mean = 610.6, SD =554.4).Cannibalism was not observed experimentally or incidentallyon transforming tadpoles, but was recorded on dead and injuredtadpoles. In 1985, cattle fed and watered directly in the main studypool. The cows killed some tadpoles and mortally wounded otherswhen they waded in the pond. Dead and injured tadpoles burstopen so that their intestines were exposed. Unaffected tadpolesate the intestines of both dead and live tadpoles as well as otherinternal organs. The cannibals did not eat the remainder of thetadpoles’ bodies (e.g., head, back, tail) until several days later whenthe carcasses were affected by fungus and algae. The cattle’s hoovesalso created water-filled depressions along the pond’s margin. Fluctuationsin water levels caused some of the depressions to becomeseparated from the main body of water, trapping tadpoles that diedwhen the water evaporated. When the water level rose again, tadpolesformed feeding aggregations on the dead tadpoles.Toads appeared to employ a flexible breeding strategy in responseto annual hydrologic conditions that appeared to be relatedto the incidence of oophagy. During dry years (1985, 1986), theywere explosive breeders and females deposited their eggs in a periodof a few days. In wet years (1984, 1987), they were prolongedbreeders and females deposited their eggs over a period of twomonths. During prolonged breeding seasons, oophagy was observedin all study pools, except in temporary pools in which onlyone clutch was deposited. In explosive breeding years, few to nofeeding stage tadpoles were present that could eat conspecific eggsas there were only a few days of overlap in the time of occurrenceof eggs and larvae.Thirty-eight of 118 egg masses (32%) were completely eatenby conspecifics. Nine of 118 egg masses were destroyed by desiccation(7.6%). Dense aggregations of feeding tadpoles formed onboth viable and nonviable clutches of eggs. Nonviable eggs wereaffected by fungus, and the outer jelly became coated with greenalgae. Females typically deposited multiple, discrete clumps ofeggs. Asynchronous hatching of eggs was recorded in 75.6% ofegg clutches (N = 91; range = 1–4 days). Asynchronous developmentof embryos within clutches provided opportunities for siblingcannibalism as some tadpoles hatched up to four days beforetheir siblings. Sibling cannibalism was observed only once whentwo Stage 25 tadpoles ate a Stage 20 tadpole. All three tadpoleswere from the same discrete clump of eggs.Female toads appeared to select egg deposition sites away fromegg clutches and aggregations of tadpoles (unpubl. data). Due topatterns of egg deposition and oophagy, few situations existed inthe field where tadpoles greater than Stage 27 could prey on newlyhatched tadpoles. The females’ egg laying was not always effectiveat preventing complete depredation. In 1984, ten clutches ofeggs were entirely consumed in less than five days.Analysis of covariance, with SVL as a covariate, revealed nosignificant differences in GL or OH length between cannibals (N= 34) and noncannibals (N = 36) for these variables. The use ofdevelopmental stage as a covariate in addition to SVL also showedno significant difference between cannibals and noncannibals foreither OH (F = 0.32; df = 1, 70; p > 0.05) or GL (F = 0.79; df = 1,70; p > 0.05). The standardized residuals of OH (mean = 2.68, SD= 8) and GL (mean = 144.3, SD = 113.5) regressed against SVL(mean = 13.8, SD = 8.9) were used to check for bimodality for asubset of tadpoles randomly collected from a single pond (N =157). The results showed normal curves, which suggest that onlyone morphotype was present (see Pfennig 1990).There was a difference in the number of posterior labial teethrows between cannibals and noncannibals (χ 2 = 13.2, df = 3, p 0.05). Cannibalshad more rows of posterior teeth (mean = 1.85, SD = 1,range = 0–3) than non-cannibals (mean = 0.9, SD = 1.2, range =0–3).The number of labial teeth rows varied among tadpoles sampledfrom the same pool from 1984–1987. Analysis of variance forhomogeneity among samples of tadpoles from four different yearsrevealed that the differences in mean number of posterior and anteriorlabial teeth rows among the years were significant (posterior:F = 18.4; df = 3, 199; p < 0.001; anterior: F = 7.8; df = 3, 199;p < 0.001). There was also a difference in the mean number ofposterior labial teeth rows among samples of tadpoles collectedfrom three different pools (F = 6.5; df = 2, 77; p < 0.01), but notfor mean number of anterior labial teeth rows (F = 1.2; df = 2, 77;152 Herpetological Review 39(2), 2008