Carnivoran Frugivory and its Effect on Seed Dispersal, Plant Community Composition, Migration, and Biotic Carbon Storage

Seed dispersal by animals is important for the ecology of plants. It is particularly important to understand which animals are involved and how they move seeds differently from one another. Some seed dispersers are understudied despite ample evidence they consume fruits and seeds. This includes animals commonly referred to as carnivores in the order Carnivora. The overall goal of my dissertation was to describe the extent and quality of seed dispersal by Carnivorans, estimate important aspects of seed dispersal for a specific Carnivoran, the coyote, and estimate how differences between a coyote and songbirds affect where plants will occur in the future and if that changes how much carbon plants store on the landscape. To achieve these goals, I first systematically reviewed existing research on frugivory and seed dispersal by Carnivorans. Then, I experimentally evaluated how long it takes for seeds to pass through a coyote, and if the consumption of seeds by coyotes negatively affects seed germination or viability. Finally, I modeled how differences in the distances that coyotes carry seeds vs. songbirds affect plant migrations. I found that Carnivoran frugivory and seed dispersal are common, involve many plant species, and occur worldwide across most ecosystems. Carnivorans also rarely damage seeds or hamper seed viability and germination when they consume and disperse seeds. Furthermore, I found that coyotes generally take between 4 and 24 hours to pass seeds from the fruits they consumed and deliver seeds to new landscapes without harming them. Given coyote travel speeds, these results suggest that coyotes regularly disperse seeds up to 5 km. This seed dispersal distance is substantially greater than songbirds and led to a 2.5 times larger expansion of where junipers grew in models extending 80 years into the future. Coyote seed dispersal would also result in 3.4 times greater conversion of grasslands and an increase total biotic carbon storage by 1.1 Pg. My findings show that understudied seed dispersers like Carnivorans can greatly impact plant ecology and ecosystem services and highlights the need for further studies on the impacts of Carnivora on seed dispersal

Frugivory by Coyotes Decreases the Time to Germination and Increases the Growth of Netleaf Hackberry (Celtis reticulata) Seedlings

Research Highlights: Frugivory by mammals is a common plant–animal interaction, but additional studies that examine the effects of frugivory on woody plants are needed. We show that ingestion of netleaf hackberry (Celtis reticulata Torr.) fruits by coyotes (Canis latrans Say) cuts the time to germination nearly in half and results in seedlings that are taller than the controls. Background and Objectives: Netleaf hackberry is a deciduous shrub to small tree that can be long-lived, but newly established stands are rare. The lack of juvenile hackberry in its native range of southwestern North America could be due to low percentages of germination and seedling survival. We hypothesized that passage through the digestive tract of a coyote would increase the germination and subsequent growth of netleaf hackberry. Materials and Methods: In the Wasatch Mountains of Utah, we collected coyote scats containing visible hackberry fruits and picked fresh fruits from nearby hackberry shrubs. All samples were cleaned and cold-stratified. We sowed 20 seeds from each of the 34 samples into containers in the greenhouse (a total of 680 seeds). We noted the date of emergence and final height of each seedling after 131 days. Results: The germination percentage of the coyote-treatment seeds did not differ from that of the controls. However, the coyote-ingested seeds took just over half as many days to germinate as did the undigested controls (35 days vs. 69 days, respectively; p < 0.001) and the resulting seedlings were 9.5% taller by the end of the growing season (6.4 vs. 5.8 cm, respectively; p < 0.001). Conclusions: Consumption by coyotes can benefit hackberries by enabling their seeds to germinate earlier in the year when conditions are wetter and cooler. The additional time for establishment and growth afforded by frugivory likely increases the fitness of netleaf hackberry seedlings that emerge into the unpredictable conditions of a semi-arid region