It is very interesting NEDOC. As I have thought about it further, I've wondered if the realized prey is not actually optimum. One way to reconcile this is by the prey cross section. A predator may be most inclined to capture prey whose cross sectional area falls in a particular range.

With regard to the pellet, consider a chunk most appropriate for a 20" LMB which is .15*20*.25 = .75" and this displaces about .015 lbs of water or about 0.3% the weight of the 20" LMB at standard weight.

The cross section, however, most closely resembles prey of fusiform shape. Consider the juvenile LMB which is not precisely fusiform but only modestly laterally compressed. We can calculate the required width to have a comparable cross section to the optimum pellet. If we assume the optimum LMB prey weight to be 1% its weight then it will be 5" long. Given an LMB has a height ~23% its length (.23*5=1.15")one may calculate the width required to match the ideal pellet cross section:

_____.75^2
W = -------- = .49"
______1.15

OK So I don't know the width of a 5" LMB but if it is about 1/2 inch then the ideal pellet cross section is consistent with juvenile LMB prey at 1% relative weight.

We can also consider BG prey. At 1 percent for the 20" LMB, we get BG 4.1" long with a height of 1.48". Calculating the width to match the ideal pellet cross section:


______.75^2
W = -------- = .38" ~ 3/8"
______1.48

Again I don't know if the width of 4.1" BG is ~3/8 inch ... but if it is ... then the ideal pellet cross section is consistent with BG prey weight at 1% relative weight.

It seems to me that it is worth further investigation if for no other reason than to test the hypothesis. If confirmed, we have two different observations that are in corroboration. The pellet observations are controlled and their inclination to eat pellets probabilistically according to cross section can be argued to be related to innate behavior. We may argue this because pellets are not animate and cannot evade predation. If this cross section is consistent with the cross section of the most probable realized prey we have a powerful argument that realized prey are the same prey a predator is most inclined (by behavior as demonstrated by pellet consumption) to eat.

Under such a scenario the distribution of prey is of critical importance. It is possible to have a predator in declining condition despite there being a preponderance of prey that it could swallow if it were only inclined to do so.

Last edited by jpsdad; 09/21/19 05:42 PM.
It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers