Our results show that large apex hypercarnivorous felids may potentially and directly interact with primary producers at the bottom of food webs by processes other than by limiting herbivore populations and subsequent trophic cascades, but with similar potential for additional ecosystem effects11. In addition to the potential local demographic effects on plant populations for the recruitment of new individuals, long distance seed dispersal involving cougars may play a role in large-scale ecosystems processes such as the maintenance of metapopulation dynamics, gene flow between populations and the colonization of new and unoccupied habitats by plants4. While the estimation of demographic effects on plant populations could be affected by the estimated number of dispersing individuals (i.e. abundance of cougars) that later determines the final number of seeds disseminated, processes of connectivity, gene flow and colonization of new areas are usually determined by the dispersion and establishing of only a small number of new seedlings per year. However, the extent and quantification of any ecosystem effects due to cougars preying on seed-eating birds should be determined through additional research.

Long distance seed dispersal process involving top bird predators as secondary disperser are well documented and studied in depth only in the Canary Archipelago14,15,16. In this volcanic island ecosystems, two predatory birds, the Eurasian kestrel (Falco tinnunculus) and the southern grey shrike (Lanius meridionalis), are effective secondary dispersers of a variety of seeds of fleshy-fruited plants previously consumed by one of their main prey, the frugivorous lizards of genus Gallotia. These seed dispersal systems involving top-predators, frugivorous prey and plants could be important for the spread and distribution of plant species among these islands, particularly in volcanic zones were lava flows create young substrates for potential plant colonization15.

The process of long-distance seed dispersal may also be of conservation concern because it could facilitate the spread of invasive plant species3. Long distance dispersal of seeds by cougars could also promote range expansion of alien plant species. The most important plant species in our study in terms of the number of seeds dispersed was the common lambsquarter, a weed native from Europe and Asia but currently cosmopolitan and widely distributed across temperate and tropical regions of the world.

Doves are not able to disperse viable seeds because all the seeds they ingest are destroyed by their powerful gizzards17. However, cougar predation on doves partially counteracts previous seed removal by birds, allowing the dispersal of seeds that otherwise are eliminated from plant populations as a consequence of granivory by birds. In addition, seed dispersal from predator-prey interaction of these two generalized dispersal vectors may result in relatively high levels of dispersal of seeds, due to both the high mobility and seed carrying capacity of each of them. Doves may carry thousands of seeds in their crops and are able to travel up to 120 km daily from breeding colonies to foraging sites17, whereas cougars move up to four km in just five hours between camera trap stations in our study area.

Unlike other documented processes of primary and secondary seed dispersal by endozoochory, where seed dispersal takes place in synchrony with plant reproductive phenology after plant fruiting, the occurrence of seeds in cougar scats was distributed throughout the year (Fig. 3). This singularity in the temporal pattern of secondary dispersal process by cougars is largely determined by the foraging strategies of the eared doves, which are able to consume seeds from mother plants but also from seeds available all year round in the seed bank (Costan and Sarasola, unpublished data).

Processes of secondary dispersal of seeds as those described here may be widespread, since birds as a group are the most important seed-predators in most ecosystems and overlap with wild felids in every biome and habitat where the latter are present. In the particular case of doves and cougars, population outbreaks of this bird species have also been registered in many countries throughout South America, with breeding colonies of several millions of birds reported in Argentina and Uruguay and in tropical regions of Colombia, Bolivia and Brazil18 where diversity and abundance of large and medium sized felids is high5,6. In our study area at the Parque Luro Natural Reserve, for example, abundance of doves has been estimated at over 3 million individuals (authors’ unpublished data). The eared dove population in the United States is estimated at about 274 million individuals19 and other gregarious and granivorous dove species, such as the white-winged dove (Zenaida asiatica) may also reach high densities in western United States and Mexico20. Although, cougars are recognized as generalist predators that forage on the most abundant available prey at each site, most of the studies on the diet of cougars through the Americas document cougar preference for large ungulates. However, there are considerable geographical gaps regarding the knowledge of cougar’ food habits, particularly for tropical areas in the Neotropical regions. Furthermore, cougars’ opportunistic consumption of highly gregarious and abundant birds have been previously reported. In Monte Leon National Park in southern Argentinian Patagonia, for example, the Magellanic penguin (Spheniscus magellanicus) was the most important native prey item in the diet of cougars in terms of occurrence (38.2% of Magellanic penguins vs. 25.5% of native ungulates) and second in importance among native prey in terms of biomass (24.3%)21.

Wild felids face a variety of threats that have caused substantial declines in their populations and contractions of their geographic ranges11,22. Cougars are not an exception and their range has suffered significant contractions due to human pressure during the last two centuries23. Fortunately, there is increasing recognition that removing predators from natural ecosystems comes with severe consequences, especially considering those effects derived from the lack of top-down control on the food webs and resulting cascade effects on biodiversity7,22,24. Other overlooked, little studied or still unknown ecosystem functions of feline species may also disappear along with their populations.