I'm not a modeler, so my comments may or may not be relevant. Something important for most migratory insects is that it is almost always a different generation that makes the spring flight poleward vs. the return flight in the fall to overwintering regions. And usually, there are one or more intervening generations during the summer. In the case of Monarch butterflies, for example, the generation that starts north in spring only makes it part way and another generation finishes the flight. Sometimes breeding occurs during the winter in southern latitudes as well. Another important life history characteristic for migratory insects is the timing of mating and oviposition relative to when migratory behavior is expressed. Many insects migrate before reproductive development begins after emergence from the pupa, but others have simultaneous egg development happening during their migration. There is a very large literature and a number of reviews on this topic for insects. If any of this is of interest, I can give you some citations that might be of some help.

Hi Jeffrey,

I am not sure I can be very helpuf, I am not used to that kind of model. Howver, I was just wondering whether you will use simulated or empirical data.

Based on my few knowledge ( I am more used to long-lived species and birds), does including density-dependence on both reproductive output and survival really necessary because it seems quite difficult to prove existence of such a mechanism on several species. So, it could not fit for all of your migratory species. Maybe, including some constraints like trade-off between the reproductive output and winter survival or migration distance, stop-over duration (if exists) could effect botu reproductive output and survival.

Again, I am not use to what you are going to do, and maybe, I am just off topic.

So, I hope it could help.

Cheers,

Guillaume

Thank you both for the ideas! Dr. Sappington, you raise a good point. I think we've decided to restrict the sample of potential organism life histories at least to vertebrates, for the very reason you mention - it's simpler to only have organisms that breed in one season of the year and have the potential to survive longer than a year, rather than keep both of those things flexible.

Guillaume, for this project we are using purely simulated parameter estimates. The reason I posted this question is I want to make sure that the combinations of parameter values used are plausible, ecologically and evolutionarily. I like your ideas for demographic and movement trade-offs. Right now, I'm selecting a position on the slow-fast life history continuum for each species. Then, I select mean adult mass, intercept and density-dependence coefficient for reproductive output, winter survival intercept and density-dependence coefficient, and environmental stochasticity rates based on that life history place plus some noise. Migratory survival probability is based on mass, and summer survival probability is based on maximum reproductive output. I have found sources for the directions of most of these relationships, but I had to improvise the functional forms and degrees. I might try your idea of having migratory survival also depend on distance traveled.

Thanks again,

Jeff