INTRODUCTION

Quiscalus mexicanus, known in Panama as “changos”, are birds of the family Icteridae, a species of strongly anthropogenic birds, with a high efficiency to track food in urban landscapes (Christensen 2000). They are sexually dimorphic, males are bluish-black, and females are brown, with long tails (Wehtje 2003). This species is native to Central America and northern South America; however, it is distributed throughout the American continent from Canada to Peru and in some Caribbean islands, its affinity for human communities has led it to be a tolerant and adaptable organism (American Ornithologists' Union 1998, Christensen 2000, Wehtje, 2003, Gurrola-Hidalgo et al. 2009).

Many organisms have a social structure with different hierarchical levels that are very well defined which frequently have conflicts between them, but that can contribute to the well-being of the population, so it is interesting to understand the social structure and the ethological characteristics of the different members of the colony (Kubitza et al. 2015). Previous studies on different aspects of the social behavior of Q. mexicanus have been of the interest of many researchers, such as vocal behavior (Kok 1971), physiological changes caused by rainfall (Yorzinski 2020), feeding behaviors (Grabrucker & Grabrucker 2010, Martínez et al. 2021) and behaviors exhibited in habitat use (King 2012).

Understanding how a species interacts with conspecific, heterospecific, humans, and the environment is necessary to implement effective conservation strategies both in situ and ex situ (Lichtenberg & Hallager 2008, Gokula 2011). Understanding animal behaviors helps us to better understand why animals need to survive and what behavior plays an important role in animal survival.

The purpose of this study was to propose an ethogram of the behaviors observed in Q. mexicanus as a tool for collecting data to help study their behavior in a systematic and standardized way so that it can be used to analyze quantitative data and prevent bias in observations.

MATERIALS AND METHODS

Study area

The study was conducted in La Locería, Betania, Panama City, (O 8.9848644, E 79.5331006) from July to October 2020.

A total of 13 individuals were observed for this study. The flock consisted of three males, three chicks and seven females. The birds were observed in their natural environment. Observations were sampled during an interval of 20 minutes per hour for six hours, three times a week (Total = 120 men hours). The study period was from 7:00 to 10:00 a. M. and from 2:00 a.m. to 5:00 p.m. M., Eastern Time (ET). The average distances at which the birds were observed in their habitat was five meters from the observer to the areas where the birds carried out their activities. A table was prepared to illustrate (Table 1.) the types of behaviors were observed (Smith & Wassmer 2016).

Observations were recorded in a field notebook throughout the study, capturing a greater variety of daytime behaviors. To perform the ethogram, the Smith & Wassmer (2016) methodology was used with some modifications.

RESULTS

TABLE 1.
Descriptions of behaviors exhibited by Quiscalus mexicanus

As a result of this study, 29 observed behaviors (second column of Table 1) could be divided into nine main functional categories that correspond to the first column of Table 1. As in other studies, greater activity of males and females were observed in open areas, power lines, parking lots and garbage disposal areas during the day and are more evident and boisterous at sunrise and sunset. We describe and discuss here only those behaviors related to reproduction, feeding, parental care and grooming.

Q. mexicanus are sexually dimorphic and dichromatic. Males are up to 43 cm in length (with a tail almost if its body), weigh 230 g, and are black with an iridescent luster. Females are smaller; they measure up to 33 cm in length, weigh 125 g, and are brown. Males with bright feathers are more attractive to the opposite sex. During the breeding season, the alpha longer tail male defends his harem from other males and performs most of the mattings. Females can mate with lower- ranking males when eating outside of their harem. Main sounds produced by Q. mexicanus are song, request for mating, alarm, and whistles. The most frequently heard vocalization in the breeding season is the requesting call of the male, which indicates his interest and willingness to mate. In this study we could discriminate at least 10 different vocalizations. Ten additional sounds were perceived during our observations and are described and interpreted in Table 1.

Q. mexicanus are territorial birds, males and females show various behaviors of threat and physical attack described in the Table 1 and generally the birds of lower hierarchy tend to withdraw when they are attacked so they can be displaced from the group. In some exceptional cases there is displacement of birds with a higher hierarchical rank such as an alpha male (Ficken 1963).

Despite the extreme territoriality, some members of the flock share food and objects to clean their beaks, in turn they also share the puddles to bathe. Grooming behavior is extensive and elaborate in these birds and has been described in the Table.

Females were observed taking care of their progeny and involved in collecting food for juvenile feeding. No males participated in these activities. As social birds, Q. mexicanus exhibits a varied repertoire of agonistic behaviors and a dominance-subordinance response.

Grooming to keep their feathers in the best condition consumes an important part of the Q. mexicanus time of the day. While preening, birds remove dust, dirt, and parasites from their feathers and align each feather in the optimum position Most of them preens several times a day to keep themselves healthy.

The most elaborated behavior of Q. mexicanus are those related to foraging and drinking water. We described only three major behaviors (Table 1) that require a more extensive consideration.

DISCUSSION

During courtship males exhibit intimidating poses using their tails, and stretching out their necks backwards, flying up at each other and striking (Townsend 1927). We observed that size of males is an important cause for their success during courtship, but it is also likely that their calls are key to attract females and repel potentially competitive males (Townsend 1927, Kok 1971). Their extreme sexual dimorphism is partially a result of the sexually competitive environment (Bjorklund 1991). Sexual and individual recognition play an important role in relationships and social interactions between members of a colony. Recognition among the Q. mexicanus appears to be primarily through visual or auditory cues (Kok 1971).

The main vocalizations were song, request for mating, alarm, and whistles. Song is produced mostly by males to claim territory (Cok 1971). The vocalization that is heard most frequently in the breeding season is the requesting call of the male, which indicates his interest and willingness to mate. (Cok 1971, Johnson et al. 2000). The alarm sounds are repetitive in times of extreme danger. It occurs in response to strong disturbances in nesting colonies and perches. It is usually caused by the presence of humans and other potential predators, and by panic or due to hostility from other members of the group. The call is often given in flight when the bird flees from a source of danger (Kok 1971). The whistle is given mainly in response to other individuals flying around, it starts as soon as the birds begin to move from the roost and is commonly heard early in the morning when the flocks disperse for the day, or at the end of the day when they head back to.

The uniparental care observed in Q. mexicanus correlates with their social polygyny (Gregory 2019). The females are responsible for feeding the juveniles, teaching them to hunt, defend and groom themselves.

Agonistic behaviors consist of both aggressive and submissive actions within the context of a social interaction (Wilson 1975). Agonistic encounters are observed more frequently when relationships are unclear, such as the arrival of new individuals. Subordinate individuals in general, respond to aggressive behaviors performed by higher- ranking individuals with appeasement or submissive signals or just getting away.

Since there is a dominance relationship among members of Q. mexicanus flocks then predictable dominance-subordinance responses must occur between members and the occurrence of competitive conflicts between members of a social group should decrease. Submissive postures allow avoidance of combat (Seibert 2006).

Grooming is a common behavior in most birds, and we observed it frequently during our study period, especially after bathing. The Q. mexicanus regularly groomed other members of the group, female or

male, and during courtship. We frequently observe them grooming themselves, bathing in shallow water, and scratching. As in other

species of birds, sunbathing appears to be important in thermoregulation and care of feathers (Kennedy 1969, Perera & Kotagama 2013).

Five categories of feeding behavior were observed in which females are those that carry out the greatest activity. Birds forage for food on the ground or search inside containers (Craig 1989). When searching for food on the ground, the bird walks, jumps, runs, or stands on the ground to find prey. Sometimes they carry the prey to the landing site (Fitzpatrick 1980). We were able to determine that the main diet of this species is essentially based on human food leftovers that they extract from the garbage dumps of the surrounding buildings. Additionally, they consume seeds and insects found in the substrate. Even when there is no scientific evidence yet Q. mexicanus can be behaviorally flexible when looking for food. They can innovate when accessing food that requires the creation of a new behavior, usually involving the manipulation of a tool to drink such as bottle caps that can lift and steepening for drinking rainwater (Gregory 2019).

Although it has not been reported in the literature, we observed some

Q. mexicanus submerging food in water before consuming it, such as rice, crackers, and pieces of bread. According to Morand-Ferron (2005) this action is carried out to facilitate the ingestion of hard food such as peanuts or certain insects, which suggests that the food found in these areas are not easy to ingest. Regarding the consumption of insects, previous works report these birds' removing insects from the license plates of vehicles, as if it were a kind of trap (Grabrucker & Grabrucker 2010), however, this behavior was not observed in this study.

Q. mexicanus appears to prefer urban habitats in contrast to forested habitats (Rappole et al. 1989). It competes for nesting sites with other birds, they nest in the same trees, and there are frequent agonistic interactions. It is frequently found in close association with humans, particularly in urban and suburban areas (Gregory 2019).

Regarding their interspecific behavior, they have been observed searching for food in flocks, often with other Icteridae, or other families of birds. Sometimes coexistence can end in kleptoparasitism as they can steal or take food from other birds or members of their own

species. Although they are very sociable, Q. mexicanus sometimes attacks other Quiscalus and other species of birds, pecking and aggressively flying towards them. They eat the eggs and chicks of other birds, and sometimes kill and eat other adult birds. The breeding pair defends the nest by stalking, chasing, or throwing themselves at predators, including humans.

Q. mexicanus exhibits a wide range of smart behaviors including learning and good memories and communication. They even can solve problems and use tools, both activities indicate more than just basic instinct. We conclude that Q. mexicanus possess high levels of intelligence and have behaviors that indicate that they feel things like we humans do (Barber 1993).

The rapid geographical expansion of Q. mexicanus provides an opportunity to study how sexual selection, individual vocal repertoire, and geographic variation in song of this species vary from one place to another. Data on the ecological success and rapid expansion of the range of Q. mexicanus are very important in understanding the precise effect of habitat alteration by humans and what behavioral traits determine the success of bird species. During this study we were able to observe and describe 29 specific behaviors that were grouped into nine main functional categories used to construct an ethogram that we hope will be useful to improve our knowledge about the behavior of this species, a bird that practically coexists with human beings in the Republic of Panama.

Acknowledgments

The authors thank to Dr. Daniel Cruz-Sáenz for reviewing the manuscript and for his valuable comments.

REFERENCES

Barber TX., 1993. The human nature of birds: A scientific discovery with startling implications. St Martin's Press.

Björklund M., 1991. Coming of age in fringillid birds: heterochrony in the ontogeny of secondary sexual characters. Journal of Evolutionary Biology 4:83-92.

Christensen A.F., 2000. The fifteenth- and twentieth-century colonization of the Basin of Mexico by the Great-tailed Grackle (Quiscalus mexicanus). Global Ecology and Biogeography 9:415-420.

Craig R.J., 1996. Seasonal population surveys and natural history of a Micronesian bird community. The Wilson Bulletin 246-267.

Ficken R.W., 1963. Courtship and agonistic behavior of the Common Grackle, Quiscalus quiscula. The Auk 80:52-72.

Fitzpatrick J.W., 1980. Foraging behavior of Neotropical tyrant flycatchers. The Condor 82:43-57.

Grabrucker S. & Grabrucker A.M., 2010. Rare feeding behavior of great-tailed grackles (Quiscalus mexicanus) in the extreme habitat of Death Valley. The Open Ornithology Journal .:101-104.

Gregory B.P., 2019. Quiscalus mexicanus vocalization pitch and traffic noise in breeding populations along the Cinta Costera highway and in downtown Gamboa, Panamá. SIT Graduate Institute/SIT Study Abroad. SIT Digital Collections

Gokula V., 2011. An ethogram of Spot-billed Pelican (Pelecanus philippensis). Chinese Birds 2: 183-192.

Gurrola-Hidalgo M.A., Sánchez-Hernández C. & Romero-Almaraz M.L., 2009. Novel food sources for Quiscalus mexicanus and Cyanocorax sanblasianus in Chamela, Jalisco coast, Mexico. Acta Zoològica Mexicana 25:427-430.

Johnson K., DuVal E., Kielt M. & Hughes C., 2000. Male mating strategies and the mating system of great-tailed grackles. Behavioral Ecology 11:132-141.

King C., 2012. Habitat use and behavior of Great-tailed Grackles (Quiscalus mexicanus) in urban and peri-urban habitats of San Marcos. M.Sc. Thesis Texas State University. Hays County, Texas, US.

Kok O.B., 1971. Vocal behavior of the Great-tailed Grackle (Quiscalus mexicanus prosopidicola). The Condor 73:348-363.

Kubitza R.J., Suhonen J. & Vuorisalo T., 2015. Effects of experimental perturbation of group structure on hierarchy formation and behaviour in house sparrows. Ornis Fennica 92:157.

Lichtenberg E. M. & Hallager S., 2008. A description of commonly observed behaviors for the kori bustard (Ardeotis kori). Journal of Ethology 26:17-34.

Martínez R.J., Herrera J.M., Wilson B., Araúz J. & Quirós D. I., 2021. FOUR REPORTS OF PREDATION OF Quiscalus mexicanus (PASSERIFORMES: ICTERIDAE) IN PANAMA CITY. Tecnociencia 23v(2):36-45.

Morand-Ferron J., 2005. Dunking behavior in American Crows. The Wilson Bulletin 117:405-407.

Perera S.J. & Kotogama S.W., 2013. A descriptive ethogram for the behavior of Black Robin Saxicoloides fulicatus leucopterus (Linnaeus, 1766) in a semideveloped, intermediate zone habitat of Sri Lanka. Siyoth 3:49–57.

Rappole J.H., Ramos, M. A. & Winker K., 1989. Wintering Wood Thrush movements and mortality in southern Veracruz. The Auk 106:402-410.

Seibert L. M., 2006. Social behavior of psittacine birds. Manual of parrot behavior, 1.

Smith O. & Wassmer T., 2016. An ethogram of commonly observed behaviors of the endangered Bridled White-eye (Zosterops conspicillatus) in a Zoo Setting. The Wilson Journal of Ornithology, 128(3), 647-653.

Yorzinski J.L., 2020. Blinking behavior in great‐tailed grackles (Quiscalus mexicanus) increases during simulated rainfall. Ethology 126:519-527.

Wethje W., 2003. The range expansion of the great-tailed grackle (Quiscalus mexicanus Gmelin) in North America since 1880. Journal Biogeography 30:1593-1607.

American Ornithologists' Union., 1998. Checklist of North American Birds. 7th ed. American Ornithologists' Union Washington DC, US.

Wilson E.O., 1975. Sociobiology. Belknap Press, Cambridge, UK.