SHORTCOMMUNICATIONRevista Brasileira de Ornitologia, 22(2), 234-237 June 2014 Black-legged (Chunga burmeisteri) and Red-legged (Cariama cristata) Seriemas represent the family Cariamidae (Remsen et al. 2014), which is somewhat poorly known. Alvarenga (1982) indicated they are the closest living relatives of giant predatory Cenozoic birds (i.e., Brontornis and Mesembriornis) similar to Diatryma. Despite their large size, loud vocalizations, and overall conspicuousness, relatively little has been published on this family, which is surprising considering how common they are in many areas of South America (Redford and Peters 1986). This is especially true for Chunga, for which comparatively little is known relative to Cariama (c.f., Gonzaga 1996). Most of the information published on this family in the last two decades has related to captive birds (e.g., de Almeida 1994; Collins 1998; Hallager 2004; Padget 2010). The objective of this note is to describe basic ecology of Chunga and Cariama, and determine whether habitat partitioning occurs between these taxa. Such mechanisms of allocation reduce the possibility of competition among species filling similar niches (Brooks et al. 2001). Additionally anecdotal biological observations are reported from studying a baited family group of Chunga. METHODS Study region The main study site was Estancia Fortín Toledo (hereafter Ecological notes on Seriema species in the Paraguayan Chaco, with observations on Chunga biology Daniel M. Brooks Houston Museum of Natural Science, Department of Vertebrate Zoology, 5555 Hermann Park Drive, Houston, Texas 77030-1799, USA – dbrooks@hmns.org Received on 18 August 2013. Accepted on 01 October 2013. ABSTRACT: I studied the ecology of Black-legged (Chunga burmeisteri) and Red-legged (Cariama cristata) Seriemas in the central Paraguayan Chaco from September 1989 to August 1990, including observations of a baited family group of Chunga. Both species are allotopic in habitat use, with Chunga typically associated with drier forested areas and Cariama inhabiting savanna and wetland periphery. Interspecific territories were overlapping. Wind velocity and temperature correlated significantly with activity of Cariama and baited Chunga, respectively. The average density of Chunga was 0.38/km2. Reptiles are an important prey item and I describe an interesting feeding behavior. The breeding season in Chunga takes place during the Paraguayan summer (November – March). Bonding and courtship occurred around November and December, and the following 13 weeks were used for nest building, incubation, hatching, and chick development. KEYWORDS: Black-legged Seriema; breeding cycle; Chaco; habitat allotopy; Paraguay; Red-legged Seriema; tool use Toledo; 22°33'S; 60°30'W), located in the center of the Paraguayan Chaco (Department Boquerón) 35 km west of the Mennonite town of Filadelfia. This area has been extensively cleared for cattle production, like much of the central Paraguayan Chaco (Benirschke et al. 1989). The region is primarily grassland pasture punctuated with man-made ponds (tajamares) and some small forest tracts. The primary forest type is Quebracho Woodland (Short 1975) with thorny leguminous bushes (e.g., Prosopis ruscifolia) and Opuntia cactus (Lopez et al. 1987) as the dominant plants, with scattered trees (e.g., Aspidosperma quebracho, Bulnesia sarmientii, and Schinopsis sp.) up to 13 m in height. Isolated tracts of dense thorn forest are sometimes left remaining when land is cleared for agrarian purposes. Spiny terrestrial plants such as bayonet bromeliads (Bromelia serra) and star cactus (Cleistocactus baumannii) comprise dominant understory plants (Stabler 1985). Mean annual temperature is 26 Co and annual rainfall is 865 mm (Brooks 1998). I also made observations on transects in the northern Chaco, a north-south habitat transition from the middle to upper Chaco was noted, with the latter characterized by increased forest stratification and higher canopy, less dense and thorny foliage, and an overall greater abundance of broadleaf species. I identified general habitat occupancy by overlapping a macrohabitat map (Olson et al. 2001) with seriema range maps from NatureServe (2014). 235 Revista Brasileira de Ornitologia, 22(2), 2014 Ecological notes on Seriema species in the Paraguayan Chaco, with observations on Chunga biology Daniel M. Brooks Field methods Field data were collected between September 1989– August 1990, during direct encounters while driving unpaved road transects. Weekly surveys extended 35 km from eastern Toledo to Filadelfia (70 km round-trip), and monthly surveys extended 9.3 km through western Toledo. Other areas were randomly surveyed during various times of the year. Additionally, approximately 2 km were walked daily to collect data on habitat association. Chunga density was determined using strip transects following Balph et al. (1977). The road from Toledo to Filadelfla and back (70 km round-trip) was driven weekly during daylight hours. All seriemas seen 10 m from the center of the road were counted, and the resulting surveyed area comprised a 1.4 km2 plot. Daily observations of a familial group of Chunga lured to a baited site were made from a blind located 8 m from the bait. Study hours in the blind ranged from 0530–2000 h and averaged 225 min/day. Identification of individuals was possible using a combination of differences in size, feather arrangement, and plumage tint. Temperature (Co) was recorded using a standard thermometer; rainfall (mm) was recorded using a standard rain gauge; cloud cover (clear = 1, partly cloudy = 3, cloudy = 5, overcast = 7, or rainy = 9); and relative wind velocity (stagnant = 1, occasional light breeze = 3, consistent light wind = 5, or windy = 7) were recorded several times during daylight hours. Monthly means were obtained for temperature, cloud cover, and relative wind velocity; a monthly total was obtained for mm of rainfall. The effects of these individual abiotic parameters on seriema activity (encounters) were measured using Pearson product-moment correlations. RESULTS Habitat allotopy Both species of seriema were observed < 0.5 km from forest tracts at Toledo. Although Chunga were frequently observed within these isolated tracts, Cariama were not. Moreover Chunga were always observed in more xeric areas, whereas Cariama were often associated with open, seasonally inundated conditions such as mesic savanna or wetland periphery. During a survey in the northern part of the Chaco, which contains more forest and is less developed than the central Chaco, Chunga were seen on two separate occasions (group sizes = 1 and 2), with tracks at a third locale, and vocalizations just north of the Bolivian border. Cariama were not encountered during this survey of forested habitat, reinforcing that these two species are allotopic with regards to habitat selection. The geographic range of Chunga is not entirely sympatric with Cariama (Fig. 1), having a more westward distribution in Argentina. Overlapping the geographic ranges of both species (NatureServe 2014) with associated habitats of biomes (Olson et al. 2001) corroborates that Chunga are restricted to drier forested areas, whereas Cariama are adapted to more open often mesic environments. Additional ecological factors In transitional patches between xeric forest and open habitats, seriemas were spatially sympatric. For example, an individual Chunga was observed ca. 30 m from a family of Cariama (an adult pair and two juveniles), suggesting that exclusive territories overlap interspecifically and direct competition may not occur between the two species. Four abiotic factors (temperature, wind, rainfall, and cloud cover) were each correlated with activity of Cariama and baited and non-baited Chunga to assess if these environmental parameters influenced seriema activity. The only significant correlation with Cariama activity was wind (r = 0.324, P <0.05, n = 48), and no significant correlations were found with non-baited Chunga. The only significant correlation with baited Chunga was temperature (r = 0.372, P < 0.05, n = 48), reflecting increased activity during warmer periods. Both species would stand in tree shade on excessively hot days. Chunga were relatively inactive at temperatures less than 27° C, and none were encountered during surveys with temperatures < 27° C. Although rainfall was not significant, baited Chunga left the feeding site during heavy, but not light, rain showers. Chunga biology Chunga density ranged 0 - 2.14/km2 monthly with an annual mean of 0.38/km2. Mean densities for the Austral spring = 0.35/km2, summer = 0.29/km2, fall = 0.80/km2, and winter = 0.11/km2. Each Chunga spent an average of 3 min (N = 108 separate visits) at the baited site, with a mode of < 1 min (n = 37, 34% of all observations) in the general viewable area. Non-bait food items consumed included a grass (appeared to be buffel grass Cenchrus ciliaris), leguminous shoots from algarrobo trees (Prosopis alba), large grasshoppers (Acrididae), green Ameiva lizards (Ameiva ameiva), small snakes (Liophis sp.), and small unidentified passerines. The presence of the baited group at the site diminished during periods of high rainfall likely reflects reduced dependence upon the bait site due to increased activity of reptiles, which appeared to make up the bulk of their natural diet. An interesting feeding behavior was observed that could be interpreted as a form of tool use. Chunga used 236 Revista Brasileira de Ornitologia, 22(2), 2014 Ecological notes on Seriema species in the Paraguayan Chaco, with observations on Chunga biology Daniel M. Brooks ‘anvils’ (i.e., cracking bases) to crack open hard boiled eggs and galletas (hardened pastry). By seizing a food item in the bill and raising it high above the head (head and neck perpendicular to ground), the bird swung down and released the food, smashing it over the anvil. This behavior was observed > 225 times and involved different types of anvils (i.e., salt lick rock, brick, lumber, or hard squash). The smaller pieces were consumed once a food item was broken. If an item was only cracked in two, the smaller piece would be smashed again or the larger piece would be held steady with the foot while the inner portions were consumed. Usually the food item was cracked within the first few throws. Accuracy of hitting the anvil diminished with number of throws. On one occasion a food item was thrown 12 times on four different anvils (hard squash, brick, lumber, and salt rock) before the item was consumed. After a few unsuccessful throws a food item was usually exchanged for another. The breeding season in Chunga is during the Austral summer (December–February) when temperature and wind are fairly constant and high rainfall results in abundant food availability. Sightings of non-baited Chunga decreased slightly during this period (see above) due to established territories and nesting behavior commencing. Although typically a single chick is raised, two juveniles were observed with their parents on one occasion. Specific breeding dates and events were observed from the baited pair, as follows: 13 November: Pair arrives together at the feeding site for the first time 1 December: Pair observed unison calling 3 December: Courtship observed 7 December–7 March: Pair absent 8 March: One of the adults returns to the feeding site with a juvenile. Thus nest building, incubation, hatching, and growth is approximately 13 weeks. DISCUSSION The results suggest Chunga is associated with more xeric areas, whereas Cariama is found in more open, often mesic habitats. This was observed at the main study site, as well as in other parts of the Chaco, and was also confirmed by overlaying range to habitat maps. While these results essentially corroborate the findings of others (cf. Gonzaga 1996), the findings of lack of interspecific territoriality, and the influence of various abiotic components are apparently novel to this study. Specifically, a single Chunga was observed near an adult pair of Cariama with offspring with no territorial consequence. Additionally wind velocity was significantly correlated with Cariama activity, and temperature was correlated with baited Chunga activity. Many of the results for Chunga biology are novel, including density (seasonal mean, annual mean, and range) and feeding habits (e.g., reptiles in the diet), and certain aspects of reproduction (cf. Gonzaga 1996). The behavior involving utilizing an anvil to break food items is similar to that described in other species of birds, such as Egyptian Vultures (Neophron percnopterus; Van Lawick-Goodall and Van Lawick 1966). This could be considered a form of tool use because the anvil is an inanimate object serving as a functional extension of the animal (McFarland 1987), and the behavior was observed on numerous occasions (n ≥ 225) upon different anvils. More detailed autecological studies of habitat association, food habits, behavioral and reproductive ecology would be fertile areas for future research. In particular, the ability to quantify habitat with movements using telemetry equipment would be fruitful, as well as the ability to quantify preferred prey. ACKNOWLEDGMENTS I am grateful for the companionship of several individuals in Paraguay, including Eddie and Sonja; Jakob, Maria, and Dominik Unger; Chaco Solar caballeros Eduardo and Carlo, and some of the local Mennonites. Several Paraguayan government and non-government organizations supported research in more ways than one: Ministerio de Agricultura y Ganaderia, Servicio Forestal Nacional, Inventario Biológico Nacional, Centro de Datos para la Conservación, and Fundación Moises Bertoni. Financial Support was provided by Dr. Kurt Benirschke and the Foundation for Endangered Animals. I appreciate the comments of Rob Clay, Kini Roesler, Floyd Hayes, and Jack Hailman on previous drafts of this manuscript. Finally, thanks to Luciano Naka for encouragement to ‘blow the dust off’ this manuscript, and update it for inclusion in the Juan Mazar Barnett Memorial volume. The data herein were collected during a very early time in my career (I was 22)… hot water, electricity, air-conditioning, phones, television, and stereos were non-existent when I lived in the Chaco, but the fauna was diverse and abundant and provided ample diversion during non-sleeping hours. REFERENCES Alvarenga, H. M. F. 1982. Uma gigantesca ave fossil do Cenozoico brasileiro. Anais Academia Brasileira de Ciências, 54: 697-712. Balph, M.H.; Stoddart, L.C. & Balph, D.F. 1977. A simple technique for analyzing bird transect counts, Auk 94: 606-607. Benirschke, K.; Byrd M.L. & Low, R.J. 1989. 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