##Default assumption:

If HandlingTime_sec is not NA and > 0, it was a completed capture event.

## 
## ---- Fish summary quick view ----
## # A tibble: 3 × 4
##   Sp            n_fish mean_attacks mean_consumed
##   <fct>          <int>        <dbl>         <dbl>
## 1 P. reticulata     11         23.3          11.4
## 2 P. harpagos       12         24.3          15.9
## 3 P. vivipara       12         20.4          19.7

Differences in Total Intake

Given 10 minutes and identical prey availability, do species differ in how many larvae they can convert into intake?

##  Family: nbinom2  ( log )
## Formula:          n_consumed_10min ~ Sp
## Data: fish_sum2
## 
##       AIC       BIC    logLik -2*log(L)  df.resid 
##     214.1     220.3    -103.0     206.1        31 
## 
## 
## Dispersion parameter for nbinom2 family ():  396 
## 
## Conditional model:
##               Estimate Std. Error z value Pr(>|z|)    
## (Intercept)    2.43042    0.09072  26.792  < 2e-16 ***
## SpP. harpagos  0.33695    0.11694   2.881  0.00396 ** 
## SpP. vivipara  0.54851    0.11259   4.872 1.11e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Species differed significantly in feeding efficiency, measured as the total number of larvae consumed during a 10-min assay (negative binomial GLM). Relative to P. reticulata, P. harpagos consumed approximately 40% more larvae (p = 0.004), whereas P. vivipara exhibited a substantially higher intake, consuming ~73% more larvae (p < 10⁻⁶). These results indicate a clear ranking in feeding efficiency among species, with P. vivipara outperforming both P. harpagos and P. reticulata under standardized prey availability.

Differences in prey-capture speed through time

Do species differ in how quickly they capture prey through time?

To answer this question, we fitted a Cox proportional hazards mixed-effects model (frailty model), including fish identity as a random effect, to test for species differences in prey-capture speed.

## Mixed effects coxme model
##  Formula: Surv(event_sec) ~ Sp + (1 | ID) 
##     Data: cons_events 
## 
##   events, n = 552, 552
## 
## Random effects:
##   group  variable        sd  variance
## 1    ID Intercept 0.6180553 0.3819924
##                   Chisq    df p   AIC   BIC
## Integrated loglik 244.5  3.00 0 238.5 225.6
##  Penalized loglik 336.3 28.67 0 278.9 155.2
## 
## Fixed effects:
##                  coef exp(coef) se(coef)     z        p
## SpP. harpagos -0.3027    0.7388   0.2875 -1.05    0.292
## SpP. vivipara  1.2977    3.6607   0.2884  4.50 6.82e-06

Species differed markedly in prey-capture speed through time. Event-time mixed-effects models revealed that P. vivipara captured prey at a substantially higher rate than P. reticulata, with an estimated 3.7-fold increase in instantaneous capture probability (hazard ratio = 3.66, p < 10⁻⁵). In contrast, prey-capture rates of P. harpagos did not differ significantly from those of P. reticulata (hazard ratio = 0.74, p = 0.29). These results indicate that species differences in feeding efficiency are driven primarily by pronounced differences in capture tempo, rather than by subtle variation among all taxa.