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CALIFORNIA STATE UNIVERSITY, NORTHRIDGE

Niche Segregation Between two Armadillos in the Southern Pantanal, Brazil

A thesis submitted in partial fulfillment of the requirements

For the degree of Master of Science in Biology,

Jeffrey Mark Esparza

May 2021 The thesis of Jeffrey Mark Esparza is approved:

______Dr. Tim Karels Date

______Dr. Casey terHorst Date

______Dr. Fritz Hertel, Chair Date

California State University, Northridge

Acknowledgements

This thesis would not have been possible without the extended help from so many different sources. First and foremost, I’d like to thank my thesis advisor and mentor, Dr. Fritz

Hertel. Dr. Fritz Hertel always respected me as scientist and challenged me to think things through on my own. His respect and encouragement in the lab and in the field helped mold my thesis and I would not have been a successful candidate without his expertise.

Thank you to my committee members Dr. Tim Karels and Dr. Casey terHorst for the extended mentorship. Dr. Tim Karels was a wealth of knowledge in ecology and always challenged me to think about this project from an ecological perspective. Dr. Casey terHorst not only listened to my endless questions on my project, but provided key insight on how to navigate academia as an early career ecologist.

Thank you to CSUN Graduate Studies Thesis / Dissertation Support Program and to the

MARC/RISE Program (Grant # GM063787) for funding my thesis project and graduate program. I’d also like to thank Dr. MariaElena Zavala for sponsoring my RISE position for the first two years of the graduate program. I made countless connections and friends through RISE and I am forever grateful for the opportunity to be part of scientific collective dedicated to increasing diversity and inclusivity in STEM.

Thank you to all the friends I made here in this graduate program. It was a pleasure to wander the halls of the third floor and chat with everyone about our passion for scientific discovery. I’d specifically like to thank my lab mates, Jake Holmes, Elliott Bloom, and Rennie

McIntosh, for the extended feedback on my thesis proposal and defense. Furthermore, I’d like to

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thank all the faculty and staff in the Department of Biology for their never-ending wisdom and expertise in all areas of biology.

Thank you to Dr. Anthony Giordano for the mentorship with this project and beyond.

Special thanks to Gabby Palomo for the help in organizing my camera-trap data with her expert knowledge with R. Thank you to Henrique Villa Boas Concone for his dedicated help with my thesis proposal, field support, data analysis, final manuscript, and friendship. Henrique’s expert knowledge of the Pantanal was inspiring and his passion for conservation fueled mine. This project would not have been possible without his help and I am forever appreciative for the opportunity he provided me.

Finally, thank you my family for nurturing and encouraging my passion for nature from such an early age. And special thanks to Melissa, Robert, and Daisy, for the never-ending love, support, and patience during this graduate program. This master’s degree was not a single accomplishment, but a shared one within our little family.

Table of Contents

Signature Page……………………………………………………………... ii

Acknowledgments…………………………………………………………. iii

Abstract……………………………………………………………………. vi

Introduction………………………………………………………………... 1

Materials and Methods…………………………………………………….. 4

Results ……………………………………………………………………... 7

Discussion…………………………………………………………………. 9

Literature Cited……………………………………………………………. 15

Abstract

Niche Segregation Between two Armadillos in the Southern Pantanal, Brazil

Jeffrey Mark Esparza

Master of Science in Biology

The Pantanal of Brazil is the largest tropical wetland in the world and home to one of the highest diversities of armadillos with up to five extant sympatric species. Among these species are the similarly sized nine-banded armadillo (Dasypus novemcinctus) and six-banded armadillo

(Euphractus sexcinctus), both highly specialized diggers with varying diets. I investigated how these two armadillos partitioned their resources and facilitated coexistence by exploring multiple aspects of their ecology including space use and activity time through camera trapping, and substrate and habitat preference in forest and open habitats. I found no significant difference between burrows in both locations (forest and grassland). There was a significant difference in activity between both species with the nine-banded armadillo exhibiting more nocturnal activity and the six-banded armadillo exhibiting more diurnal activity. Both species exhibited minimal overlap in their activity, with the highest amount occurring during the onset of the evening. This study suggests temporal segregation as a sufficient ecological strategy to reduce competitive interactions between these two armadillos. Future studies would benefit from assessing alternative niche axes between species in other ecoregions.

Introduction

Niche partitioning and other methods of coexistence such as competition can be found across the globe in a variety of taxa and systems. Often times, species partition resources as a method of reducing competition and thus promote coexistence (Rosenzweig and Sterner 1970, Schoener 1974, Wilson and Yoshimura 1994, Gravel et al. 2011). In fact, species that often have high overlap in certain niche dimensions may not be able to coexist (Hutchinson 1957). If overlap among species begins to occur in an area, it may be in the best interest of individuals to expend energy traveling to less populated areas rather than compete for resources (Schoener 1974). Thus, space and habitat would be considered an important niche axis (Schoener 1974, Rosenzweig 1981). For example, in Mexico, three species of tree-climbing nuthatches partition their habitat and space use by foraging on different areas of a tree (thin branches, thick branches, trunk) (Lara et al. 2015). In Haiti, 7 species of Anolis lizards occupy different perch and habitat types depending on their movement type and body and limb proportions (Moermond 1979).

A second important niche axis is food type (Schoener 1974). Resource partitioning to reduce dietary overlap is a common strategy seen in a variety of species. In New World monkeys, the diversity of coexisting primates is a great example of dietary shifts. Rosenberger (1992) showed that the high diversity of New World primates likely occurs through extensive dietary zones with species consuming different sources of food including exudate (tree sap), insects, nuts, fruits, and leaves depending on body size.

Finally, time is another niche axis that can often be partitioned to avoid competition (Schoener 1974, Wilson and Yoshimura 1994). Temporal segregation is a common behavioral mechanism that can be used to reduce competition if there is already overlap in diet and space (Schoener 1974, Di Bitetti et al. 2010). Camera trapping is a useful method to measure activity patterns among species and has revealed extensive evidence to support temporal segregation. Among carnivores, temporal segregation has been documented in tropical forests (Di Bitetti et al. 2010), high elevation deserts (Lucherini et al. 2009), and tropical wetlands (Bianchi et al. 2016).

In order to maintain coexistence, high overlap on any niche axis is usually accompanied by avoidance on another axis (Stewart et al. 2003). In North America, Mule deer (Odocoileus hemionus), North American elk (Cervus elaphus), and introduced cattle (Bos taurus) all exhibit low overlap in their diet during the summer season despite significant overlap in habitat use 1

(Stewart et al. 2002, Stewart et al. 2003). In South America, two species of brocket deer in the Atlantic rainforest overlap in space but exhibit temporal segregation (Ferreguetti et al. 2015). Finally, it is possible for there to be minimal overlap in multiple niche dimensions, as seen among the maned wolf (Chrysocyon brachyurus), crab-eating fox (Cerdocyon thous), and hoary fox (Lycalopex vetulus) with varied differences in diet, habitat, and activity patterns in the Brazilian Cerrado (Jacomo et al. 2004). Thus, it is essential to understand multiple niche axes to appropriately consider methods of resource partitioning.

The Pantanal is the largest tropical wetland in the world (Alho 1988) and is located predominantly in the Brazilian state of Mato Grosso do Sul. With more than 150 species of mammals, the region is one of South America’s biodiversity hotspots (Tomas et al. 2010) The tropical wetlands of southern Brazil are home to a high diversity of armadillos, with up to five extant sympatric species (Tomas et al. 2010). Armadillos are New World mammals that comprise 21 species (Wetzel 1985, Vizcaíno and Milne 2002) between the families Dasypodidae and Chlamyphoridae of the order Cingulata (Wilson and Mittermeier 2018). They exhibit unique adaptations for different degrees of fossoriality (digging lifestyle) (Vizcaino et al. 1999, Vizcaino and Milne 2002), a diet that consists of varying proportions of insects, fruits, animal prey, and plant material (Redford 1985), a protective bony armor comprised of dermal ossicles (Vizcaíno and Milne 2002), and range in sizes from the 13 cm 120 g pink fairy armadillo (Chlamyphorus truncatus) (Merritt Jr. 1985, Superina 2011) to the 30 kg giant armadillo (Priodontes maximus) (Carter et al. 2016). With over 20 extant species, armadillos provide a model organism to address coexistence theory. Despite their diversity, this group remains poorly understood (Loughry et al. 2015, Desbiez et al. 2018).

Among these are two similarly sized species: the nine-banded armadillo (Dasypus novemcinctus) and six-banded armadillo (Euphractus sexcinctus). Nine-banded armadillos have the largest geographic range among armadillos with a distribution from southern United States to northern Argentina in a variety of habitats including temperate and tropical forests, savannas, grasslands, wetlands, and disturbed habitat (i.e., pastures, ranches, urban) (Abba et al. 2014). The six-banded armadillo is also widely distributed (Loughry et al. 2014) and found in forests, savannas, grasslands, and wetlands. Furthermore, the six-banded armadillo overlaps in range

with the nine-banded armadillo across the entire country of Brazil outside of the Amazon Basin (Eisenberg and Redford 1999, Loughry et al. 2014, Ferreguetti et al. 2016).

The presence of these two species across Brazil poses unique questions in terms of how habitat and resources facilitate ecological coexistence. Prey, space, and time are excellent measures that explain coexistence among mammals, particularly carnivores (Porfirio et al. 2016a). Armadillos demonstrate a very diverse diet among species, with the six-banded armadillos having a more carnivorous/omnivorous diet (Redford 1985, Dalponte and Tavares- Filho 2004) and the nine-banded armadillo having a more insectivorous/generalist diet (Redford 1985, Redford 1986). Because both species exhibit dietary overlap in terms of consumption of insects, reducing competition in this niche axis would facilitate their coexistence.

Armadillos also exhibit morphological adaptations for their fossorial habits (Vizcaino et al. 1999, Vizcaino and Milne 2002) and differences in morphology likely contribute to their ecological success and coexistence. Among the 21 species, the different families and subfamilies all exhibit differences in their limb morphology in relation to their primary locomotion, with some species being more cursorial (limbs adapted for running), others being more fossorial, and others that are in between with digging not being essential as an alimentary strategy (Vizcaino et al. 1999). These differences in morphology may also prove to be predictors in species substrate preference as the more powerful diggers might preferentially burrow in tougher substrate and vice versa. Despite being members of separate families, both the nine-banded and six-banded armadillo fall into the same “in-between” category (Vizcaino et al. 1999) yet preferentially burrow in different habitats. In the Atlantic rainforest of Brazil, nine-banded armadillo burrows are commonly found in swamps and forested habitats. Conversely, six-banded armadillos preferentially burrow in termite mounds and open fields (Carter and Encarnaçao 1983). Assuming that substrate differs among habitats, this could also be indicative of species presence. Furthermore, because some species can be identified by the dimensions of their burrows (Carter and Encarnaçao 1983), comparing substrate to burrow size might aid in understanding habitat preference. Therefore, I propose substrate preference and burrow shape to be an indicator of armadillo habitat preference.

Because the two species in question exhibit overlap in space and diet, alternatively, they may partition the temporal niche through differences in activity time. Activity patterns are

frequently used in studies assessing niche differentiation, but few of these studies have addressed armadillos. This could be due to their fossorial habits or to their more secretive and elusive nature. However, studies that have examined their activity have found meaningful results. In the Atlantic rainforest of Brazil, the six-banded and nine-banded armadillo exhibit contrasting activity with the latter being more diurnal and the former being more nocturnal (Ferreguetti et al. 2016). In a neighboring state in the Brazilian Pantanal, both species exhibit similar contrasting activity patterns with the most overlap occurring in the early evening (Maccarini et al. 2015). My study will further expand on these and address their activity patterns in a highly disturbed habitat. The Pantanal is mostly privately owned with a large number of cattle ranches in the surrounding area (Seidl et al. 2001), therefore understanding how wildlife can coexist among human presence is especially important.

Both of these species provide an excellent chance to assess mammalian coexistence. As it stands, the little ecological research that has been conducted on armadillos is largely restricted to the nine-banded armadillo in its extreme northern range (Wetzel 1985, McDonough and Loughry 2008, Maccarini et al. 2015). Furthermore, very few studies have assessed potential competitive interactions and resource partitioning among co-occurring armadillo species that would promote coexistence. Thus, the aim of my study is to assess the ecological (realized) niche of these two species by estimating their activity patterns through camera trapping and habitat preference through analysis of burrow location and substrate. I hypothesize that both species segregate their niche through substrate preference and/or activity time/period.

Materials and Methods

Study area

Field work took place at Fazenda San Francisco cattle-wildlife ranch and ecotourism lodge (20°5.2'S, 56°36.9'W) (Fig. 1) in July–August of 2019. This ranch is located between the highway BR 262 and native Pantanal, providing a unique opportunity for studying wildlife. The geography of the ranch is also diverse, composed of open cow pastures, irrigated rice fields, roads, and widely distributed forest patches. During this period, sunrise ranged from 6:01am– 6:07am and sunset ranged from 5:46pm–5:51pm (http://www.timeanddate.com).

Figure 1. Fazenda San Francisco cattle-wildlife ranch and ecotourism lodge located in the state of Mato Grosso do Sul, Brazil.

Habitat and substrate preference

To evaluate habitat and substrate use, I surveyed and sampled open fields and forest patches. Substrate sampling took place only in the formed pastures and native forest patches within this area (Fig. 1). I walked among the fields and forests to first identify armadillo

burrows. I then compared substrate preference of armadillo burrows in the open fields and the forest patches dispersed among the formed pastures. Burrows were common in the field and were identified by nearby armadillos, tracks at the entrance, and verified by use of camera traps. I measured several aspects of these burrows, including height (cm), width (cm), depth (cm), and aspect (degrees) of burrow entrances, distance (cm) to the nearest insect mound, and surrounding habitat, denoted by presence/absence of trees and large vegetation such as trees and shrubs. Searches for insect mounds were conducted within a 50 m radius of the burrow. If no insect mound was detected, I doubled the farthest recorded distance measured.

To assess differences in substrate, I dug a hole adjacent to each burrow to a depth of 25 cm (McDonough et al. 2000). I extracted 1 kg of soil from each hole by scraping the edges from the top to the deepest portion and then ran this sample through a set of sieves. The sieves segregated the soil by the following grain sizes: 5 mesh/4 mm, 10 mesh/2 mm, 35 mesh/0.5 mm, 60 mesh/0.25 mm, and 120 mesh/0.125 mm and less. The mass of each soil partition was then weighed (g) to determine the percentage in each size category.

Finally, burrow habitat was determined to assess any difference between species. Habitat was classified as either open (characterized by open plains and cow pastures) or forest (characterized by presence of trees and arboreal vegetation cover). A principal component analysis (PCA) was used to visualize the variables (location, substrate size of each sieve partition, height, width, depth, aspect, distance to insect mound) in multidimensional space and perMANOVA was used to test the differences between open fields and forest patches among the same variables.

Camera traps (Reconyx HyperFire 2 HF2X) were used to identify burrow diggers and assess wildlife activity around burrows. Eight camera traps were deployed in front of fresh/recent burrows in both forest areas and open areas. Cameras were positioned 1 m away from each burrow, left active for 10–12 days, then moved to different burrows in order to increase sample size during the field season. Burrows were chosen based off suspicion of recent activity, such as presence of a dirt mound at the entrance, and lack of spiderwebs or debris in front of the entrance.

Activity patterns

Camera traps (ScoutGuard SG565F, CuddeBack E-model, Reconyx HyperFire HC 500) were used to assess differences in activity patterns between the two species. Camera trap data from two surveys from an ongoing project/study on mammal communities in the study area were used in the analysis. The first survey was done from October–December 2018 with 63 camera- trap stations randomly set to cover a minimum area of 50 km². The second survey took place in 2019, from July-December, with 60 camera-trap stations also covering 50 km². Spacing of camera-traps on these surveys respected a minimum distance of 1000 m. These data were combined with the data gathered from the substrate/habitat preference camera trap surveys and evaluated together.

Activity pattern data were evaluated using R packages “camtrapR” (Niedballa et al. 2016) and “Activity” (Rowcliffe 2016). Activity for each animal was estimated from presence/absence records and the time of each photo capture. If multiple photos of an animal were taken in a shorter duration of time (< 1 hr) then only the first photograph was used for analysis to avoid pseudoreplication (Linkie and Rideout 2011, Porfirio et al. 2016b). Watson’s two sample test of homogeneity was used to test the significance between activity patterns for both species. To assess the degree of species overlap, I used the overlap coefficient Dhat4 from the R package “Overlap” (Rideout and Linkie 2009) that ranged from 0 (no overlap) to 1 (complete overlap).

Results

Habitat and substrate preference

Twenty-six burrows were measured and sampled completely, 14 in open fields and 12 in forest patches. Only eight burrows were identified correctly to species (six-banded armadillo). All but two burrows were found within a 50 m radius of an insect mound. All variables were converted to z-scores before application to the PCA. The PCA explained little variation among the variables with PC1 explaining 25.3% of variation and PC2 explaining 17.9% variation (Fig. 2). There was no significant difference found among these variables between sites (F = 1.48, df = 1, P = 0.22).

Figure 2. PCA (converted to z-scores) explains minimal variation among burrow variables between sites; percent variation accounted for by each PC in parentheses.

Activity patterns

A total of 5710 camera-trap nights occurred in three separate wildlife surveys. There was a total of 120 independent records of the six-banded armadillo and 121 records of the nine- banded armadillo. The activity patterns differed significantly between species (U2 = 2.201, P < 0.05). Six-banded armadillos exhibited more diurnal activity with a peak around 12:00 h and a second peak at 19:00 h. The nine-banded armadillo exhibited more nocturnal activity with a peak at around 19:00 h and a second peak at 01:00 h. Both species exhibited minimal overlap (Dhat4 = 0.41) with the highest amount of overlap occurring at 19:00 h (Fig. 3).

Figure 3. Activity patterns between the six-banded armadillo (Euphractus sexcinctus) and nine-banded armadillo (Dasypus novemcinctus). Tic marks below graph are actual records of occurrence and shaded area is overlap between species.

Discussion

Although there was no significant difference found in burrow metrics, they were not easily identified to species across the landscape. Burrows were commonly found in the ranch, but the only species to be identified successfully to a burrow was the six-banded armadillo. Although nine-banded and six-banded armadillos differ in shape (Wilson and Mittermeier 2018), height and width measurements were thought to be critical in testing this distinction, but this did not prove to be the case. Although nine-banded armadillos are known to dig burrows across their range (McDonough et al. 2000), local ranchers in the area insisted (pers. comm.) that nine- banded armadillos preferred reusing old burrows from six-banded armadillos.

Camera traps provided further evidence of this unique behavior. One camera trap showed evidence of an active burrow being occupied by a six-banded armadillo. On 8 July 2019 at 15:26 h a six-banded armadillo was seen entering the burrow. On the same day at 16:02 h a nine- banded armadillo was seen entering the same burrow only to retreat quickly (Fig. 4). This same behavior happened again at this station on 9 July 2019 at 18:46 h when a six-banded armadillo was recorded entering the burrow. On 10 July 2019 01:44 h, a nine-banded armadillo was seen entering this burrow only to jump out quickly. On 25 July 2019 at a different camera trap station, a six-banded armadillo was seen leaving its burrow at 18:58 h. This vacant burrow was then entered by another nine-banded armadillo at 19:07 h only for it to exit at 19:09 h. Nine-banded armadillos are known to frequently dig and abandon burrows in Brazil (McDonough et al. 2000) and this behavior might extend to other species. Furthermore, the unique behavior of using burrows from other species has been seen in other species of armadillo (Rodrigues et al. 2020 and references therein) and supports the importance of these burrows, even as facilitation, in their respective ecosystems.

Figure 4. Six-banded armadillo (Euphractus sexcinctus) (A) and nine-banded armadillo (Dasypus novemcinctus) (B) sharing a burrow.

Even though ecosystem services vary from species to species, the positive impact of armadillo presence in ecosystems is vitally important (Rodrigues et al. 2020). Burrow construction for armadillos can have a lasting effect on the landscape, with some burrows lasting years (Fontes et al. 2020). Ecosystem engineering is one principal service provided by armadillos. In the Pantanal, the giant armadillo constructs large burrows that are widely used by many vertebrate species, including the nine-banded and six-banded armadillos (Desbiez and Kluyber 2013). In other areas, burrows constructed by six-banded and nine-banded armadillos are used by small rodents, birds, and even small carnivores for various reasons (Rodrigues et al. 2020). Both species used burrows in our study area, but camera traps also provided evidence of a four eyed opossum (Philander opossum) occupying a vacant burrow and Azara’s agouti (Dasyprocta azarae) resting on a burrow mound.

An armadillo’s burrow is far more than just an occupancy location for fauna. The construction of burrows often leads to bioturbation, or the displacement and mixing of soils, which can also have profound effects on ecosystems. Bioturbation was demonstrated in our study area by potentially providing foraging sites for many species including doves (Columbiformes), Red-legged seriemas (Cariama cristata), Southern crested caracara (Caracara plancus), crab- eating foxes, Azara’s agoutis, tapetis (Sylvilagus brasiliensis), giant anteaters (Myrmecophaga tridactyla), and high numbers of arthropods. For giant armadillos, feeding excavations are more abundant than burrows in the Argentine Chaco and these are even more important in terms of soil disturbance, litter, and seed capture (Di Blanco et al. 2020). The role of feeding excavations for the smaller six-banded and nine-banded armadillos may also play a crucial role in their

ecosystem services. The relationship between bioturbation and armadillos has not been researched extensively (Rodrigues et al. 2020) and this would benefit from future studies.

Both species exhibited temporal segregation in the study area with the six-banded armadillos being active during the day and the nine-banded armadillo being active in the evening. These activity patterns have also been found in other areas of sympatry (Maccarini et al. 2015, Ferreguetti et al. 2016). Furthermore, both species exhibited high amount of overlap during the onset of the evening at around 19:00 h (Fig. 3), and similar overlap has been demonstrated in another area within the Pantanal (Maccarini et al. 2015). Temperature is also known to influence the onset of activity between both species (Maccarini et al. 2015) and this may have also contributed to the activity patterns between these two species. Armadillos are often only active for short durations and spend the rest of the time thermoregulating inside burrows (McDonough and Loughry 1997). Six-banded armadillos are physiologically adapted to warmer temperatures, which may explain their activity peaks during the hottest hours of the day (Maccarini et al. 2015). Given their extended distribution, nine-banded armadillos may exhibit more variation in terms of their temperature constraints, but more data would be needed to address this. Given that armadillos have naturally low metabolic rates (Maccarini et al. 2015), physiological studies are imperative in aiding our understanding of activity onsets among species.

Species often segregate through time to facilitate coexistence by reducing opportunities of competition (Bianchi et al. 2016). In terms of competing predators, temporal preference might depend on prey activity (Kronfeld-Schor and Dayan 2003). At Fazenda San Francisco, the presence of large carnivores such as jaguars (Panthera onca), pumas (Puma concolor), and maned wolves might influence armadillo activity. Comparisons of activity patterns among these top predators would be beneficial in understanding that potential influence.

For example, in Belize the nocturnal nine-banded armadillo is primarily preyed upon by jaguars and opportunistically preyed upon by pumas during the evening (Harmsen et al. 2010). The nine-banded armadillo also shifts to lower activity during a full moon likely as a method of reducing predator detection (Harmsen et al. 2010). In the Pantanal, however, jaguars are more diurnal and also consume larger prey such as capybaras (Hydrochoerus hydrochaeris) (Crawshaw and Quigley 1991, Harmsen et al. 2010). Because both species of cats have a wide

variety of prey that ranges from medium to larger-bodied mammals (Arnanda and Sanchez- Cordero 1996, Scognamillo et al. 2003, Harmsen et al. 2010), their activity might not influence armadillos. Likewise, whereas the maned wolf is known to consume both species of armadillo, it also consumes a large amount of fruits and plant matter (Bueno and Motta-Júnior 2004, Jacomo et al. 2004) so its consumption might be more opportunistic.

Although there is a strong presence of smaller carnivores on the ranch, such as ocelots (Leopardus pardalis) and crab-eating foxes, their presence may not have a strong influence on the temporal activity of both species. Both crab-eating foxes and ocelots are known to consume armadillos in other systems (Bueno and Motta-Júnior 2004, Abreu et al. 2008, Bianchi et al. 2010), but this alone might not be enough to influence their activity patterns. Ocelots more often prey on smaller mammals such as small rodents, marsupials, and even primates (Abreu et al. 2008, Bianchi et al. 2010). The crab-eating fox is much more of a generalist, consuming more plant matter than animal matter (Jacomo et al. 2004), thus, similar to the maned wolf, they might opportunistically prey on armadillos rather than actively hunt them.

Armadillos are at risk from similar predators, thus their contrasting activity might be explained by another source of interaction. Armadillos may trade-off vulnerability of activity if it coincides with availability of their primary prey or decreases interactions with sympatric species. For example, in the Pantanal both the naked-tail armadillo (Cabassous unicinctus) and six- banded armadillo exhibit overlap in their diurnal activity, but minimal overlap in their dietary preference (Desbiez et al. 2018).

In the Cerrado, both the six-banded and nine-banded armadillos exhibit overlap in terms of their diet (Anacleto 2007). Six-banded armadillos have an omnivorous diet that includes a high occurrence of ants (Hymenoptera) and beetles (Coleoptera) alongside other Arthropoda orders including Isoptera, Lepidoptera, Orthoptera, Araneae, and Chilopoda. Along with arhropods, the six-banded armadillo was the only species to consume vertebrates (Anura and Squamata) (Anacleto 2007). In the same study site, the nine-banded armadillo exhibited a less diverse diet with relatively equal consumption of Hymenoptera, Isoptera, and Coleoptera. However, in terms of termites (Isoptera), they consumed a higher diversity of species (5 total) (Anacleto 2007). Giant armadillos also consumed high amounts of Hymenoptera and termites (Cornitermes sp.) at this site (Anacleto 2007) but are strictly nocturnal (Silveira et al. 2009,

Desbiez et al. 2019). This may imply that the activity of their preferred prey is more cathemeral and thus temporal segregation is a sufficient strategy for coexistence. As for the nine-banded armadillo, the primary consumption of different termite species combined with lack of consumption of alternative species (chilopods, spiders, vertebrates) suggests dietary overlap is minimal. Because dietary preference of both species was not studied on the ranch, future studies would benefit from addressing this.

Due to the diversity and amount of overlap among armadillo species, niche partitioning likely arises through various means depending on the species. The nine-banded and six-banded armadillo both exhibit overlap in their morphological variation (Vizcaino et al. 1999), dietary preference (Redford 1985, Anacleto 2007), and habitat preference across their sympatric range (Abba et al. 2014, Loughry et al. 2014) so segregation in another niche axis is likely (Stewart et al. 2003). Although this study did not find a significant difference among the burrow substrate and dimensions, the substrate sampling was limited to a small section of the entire ranch. Future research comparing substrate from the ranch with more undisturbed areas and native Pantanal forest might aid in more explanation. Furthermore, the unique behavior of burrow sharing between species demonstrates the flexibility in their preference. Future studies would benefit from more concrete methods of capture and burrow identification to aid in the understanding of their burrowing tendencies.

This study showed that activity patterns between both species are significantly different, with minimal overlap occurring during the onset of the evening. Therefore, I suggest that temporal segregation is an ecological strategy that allows the species to maintain coexistence across their range. Although the ecological strategies provide important insight on identifying adaptations, physiological studies may prove to be even more useful in understanding these adaptations. The order Cingulata is incredibly diverse, yet armadillos are not heavily studied (Loughry et al. 2015, Rodrigues et al. 2019) with many species being threatened or data deficient (Superina et al. 2014). Despite this, their ecological importance cannot be understated. Their presence in ecosystems may have long-term benefits for sympatric wildlife and thus our understanding of their ecology and biology is of great importance.

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