Diverse effects of mast seeding on animal populations

Submitted by editor on 29 September 2015.Get the paper!

Mast seeding is an astonishing phenomenon. Trees produce tons of seeds, all at once, and then take a couple of years off, with little or not seeds produced. This burst of seeds creates a resouce pulse that propagates through ecosystems. The best-known effects of masting start with rodents: overabundance of food leads to a dramatic increase in rodent numbers. In turn, numerous granivores increase their predation pressure on birds nests. The increase in rodent numbers also creates another pulse of food resources for predators preying on small mammals.

 

Bank vole (Myodes glareolus) fed with beech nuts. Photo by Stanisław Pagacz.

We believed that mast effects extend beyond these best-recognized links. In passing, we have heard wildlife ecologists describing masting effects on a broad range of mammal and bird species. To look for less rigorously tested mast effects on wildlife we developed alternative search framework. In addition to “traditional” search of scientific databases we downloaded all articles from six recognized ecological journals to look for “incidental reports”. We identified dozens of papers that attributed variation in wildlife behavior or population dynamics to mast events, even if the main focus of their study was not on mast-seeding. These helped us identify interesting areas of future research. For example, it seems that birds are as responsive to masting as rodents. Yet, rodents received much more research attention, and our knowledge of direct effects of masting on birds is scarce.

Picture 1. One of the Authors (MB) handling a rodent in Bieszczady Mountains (Poland). Photo by Stanisław Pagacz. Picture 2. European jay (Garrulus glandarius) waiting for an acorn. Photo by Jakub Szymkowiak. 

We also used our database to test predictions derived from previous great conceptual reviews of population responses to pulsed resources Ostfeld and Keesing (2000, Trends Ecol Evo) and Yang et al. (2010, Ecol. Monogr.). As predicted, we found that animal responses to mast seeding vary predictably as a function of their life history traits. However, this was true only for mammals, and not for birds. This further ephasizes that mast effects of birds need more of our attention.

Michal Bogdziewicz

Picture 1. Mast year in beech (Fagus sylvatica). Photo by Stanisław Pagacz

Picture 2. Bank vole (Myodes glareolus) fed with beech nuts. Photo by Stanisław Pagacz.

Picture 3. One of the Authors (MB) handling a rodent in Bieszczady Mountains (Poland). Photo by Stanisław Pagacz.

Picture 4. European jay (Garrulus glandarius) waiting for an acorn. Photo by Jakub Szymkowiak. 

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