Just like humans, animals are a very important piece of the Earth's unique ecosystem (Owen, 2002). The human species interacts with animals on a daily basis, and one of the most common type of animal that crosses a human's path, is a duck. Mallards to be more exact, take up residence on every continent with the exception of Antarctica, and are found year-round in much of North America (Basso, 1996). Breeding, however often occurs along the east and west coasts of the United States (Owen, 2002). Mallards prefer to live in wetland areas where there is major source of water such as marshes, ponds, rivers, and lakes. In addition, unlike many other species in the animal kingdom, mallards generally form monogamous pairs due to the high dependency of their young, and nest on the ground in order to fulfill their omnivorous diet of earthworms, insects, and seeds (Basso, 1996). Though mallards are mainly found in the wild, because of their close living proximity to humans, they have become fairly domesticated and have acclimated to living among humans (Ankey, et al., 1996). This is extremely apparent on the campus of Michigan State University, where a multitude of ducks have resided, specifically on the Red Cedar River. Thousands of students pass these ducks, interacting with them and using taxes such as food to attract the ducks attention. Though these mallards exhibit an extreme form of domestication, they still look to their natural environment for resources, for communication with the other ducks, and continue to demonstrate typical mallard behavior in the Red Cedar River (Weidmann, 1971).

There is a large population of both male and female mallards on the Red Cedar River, and when observing them, it is fairly easy to differentiate between the two sexes. One of the easiest ways to distinguish between male and female mallards is by their colors (Basso, 1996). Males have a dark green head and a bright yellow bill, with gray-brown feathers on their bodies, and are usually more noticeable because they sometimes have a bright patch of color on their sides. Females, on the other hand are mostly brown and more plainly colored except for a strip of color on their sides, similar to that on the males, which is usually bright blue (Owen, 2002). This distinction between male and female coloring allows for the males to stand out, while the female ducks are discrete as to avoid predators. In addition, all ducks have an eye-line that cuts through the eye horizontally, which is less prominent in females and dark black in males (Basso, 1996). Males are most often the sender, or initiator, of a behavior, where the females are usually the receiver. Another distinguishable difference is that males usually can be observed traveling in groups with other males looking to mate (Johnsgard, 1968). It is highly possible that not all males in a bout will be able to find a mate which leads to males becoming more aggressive and therefore the more dominant sex. Observing behaviors of animals is very intriguing, and much can be learned from mallards by understanding the meanings and purposes behind each and every interaction they have.

The most common reason for communication between male and female ducks is largely based on mating. Male mallards are more active with regards to communication while the females mainly only form a response to the initiation by the male, and this is because males have been found to be the more dominant sex when it comes to communication (Ankney et al., 1996). Interaction between male and females depends on three concepts. The first is the positions of and distance between the duck sending the signal and the duck receiving the signal. The second is the posture and stance with which the sending duck is holding right before sending a signal. Lastly, the movement of both the sender and receiver while the signal is being sent (Davis, 1997). The most important of these three concepts is the position of the sender because knowing their position allows determination of the reason for the signal and who it is meant for (McKinney, 1992). Most signals are exhibited in the form of a bout. A bout is a group of signals from a male mallard that seem to proceed without any gaps between signals over a certain period of time, and usually consist of at least one of the most common courtship behaviors (Weidmann et al., 1971) The courtship behaviors exhibited by male mallards consist of the grunt-whistle, where a male dunks his bill in the water and sprays toward a female, the head-up-tail-up, where the male pushes both its head and tail out of the water, and the down-up, where the male dunks his bill into the water so his tail tilts up and then reassumes an upright position (Weidmann, 1956). The most common and often only response by female mallards is the nod swim, where the female swims with her head barely above the water surface and neck stretched out. To the nod swim, males may respond with a head-flick or a swim-shake (Davis, 1997). The positions of the sender is important in distinguishing whether these signals sent by males are a method of courtship or for another reason such as aggression (McKinney, 1992). In all of the signals except for the down-up, a male is courting when he is broadside to the female. The down-up is different because it does not follow orientation patterns; a male will face another male while sending the down-up signal to show aggression or appeasement, but he will be broadside to females when courting (Johnsgard, 1960). The context in which a male or female communicates and sends signals is imperative to understanding the reason behind the signal, whether it be showing aggression, appeasement, or courtship.

Each animal has their own behavior regarding courtship in attempt to find a suitable mate, whether they be verbal or nonverbal cues. Humans especially, rely on the universal nonverbal cues while in the beginning stages of attracting mates such as facial expressions, hand and body language, and intrapersonal distance (Givens, 1978). These specific behaviors may elicit a negative or affirmative response from a potential mate, and this response determines how the initiator will then go on to act (Grammer et al., 2000). Homologous to mallards, humans, specifically college aged (18-22 years old), exhibit a series of actions when courting, the first generally being the attraction of a possible mate (Givens, 1978). This specific age range of people are generalized to the fact that nonverbal interaction is initiated by males and is found to be more frequent when there is competition between males (Kirkendall, 1961). This stage begins with prolonged eye contact that may escalate to patterns of muscle flexion, hand placement, and possibly the affirmation of a smile (Scheflen, 1965). When the attraction is formed, and the male behaviors are directed toward a definitive person, the female generally responds with gestures such as nodding and tilting of her head, leaning into the male, and smiling (Givens, 1978). When these nonverbal cues have established a connection between two individuals, they may move onto verbal behaviors or other physical interactions which further emphasize the goal of courtship. While these physical behaviors may not hold true for all cultures, the generalization of human behaviors provides the baseline of universal nonverbal cues (Berscheid et al., 1974). Many of these courtship behaviors in humans are homologous to mallards, specifically the nodding and tilting of the head as a positive response by both species to male initiation. These common natural instincts are possibly linked by the fact that both species have similar genetics.

Genes play an important role in determining traits of all living organisms, and with regards to human courtship, the dopamine gene is important in pleasurable behavior. The neurotransmitter dopamine is released during goal oriented behavior and the D4 dopamine receptor specifically, is responsible for eliciting pleasure-seeking behavior (Koepp et al., 1998). In addition, the presence of the DRD4 gene is linked to sexual arousal and desire (Halley et al., 2016). Six polymorphisms in the DRD4 receptor have been identified as having a part in the human trait of pleasure and novelty seeking, and one polymorphism specifically was found to be statistically significant (p<0.0001) (Okuyama et al., 2000). Dopamine, therefore is released in humans during the mating process because of its link to the attraction between individuals when courting (Halley et al., 2016). In addition to humans, it is possible that the DRD4 receptor is active in animals such as mallards as they perform similar courting behaviors to humans. We predict that the DRD4 gene is present in mallards because of the affiliation in courting behaviors of both mallards and humans that have the goal of mating (Okuyama et al., 2000). If humans exhibit homologous behavior to mallards, it is probable that both species have similar genetic make-up. These homologous behaviors include the initiation of courtship behavior by males, and the gestation of the heads of females in response to males. We predict that female Mallards will respond to male's head-up-tail-up and grunt-whistle with a nod-swim or head-flick because females are unlikely to initiate courtship but rather use one of these two responses when accepting a mating call (Davis, 1997). Male mallards are generally the exclusive sex initiating behavior because they are the more dominant of the two and utilize body positions to signal the reason for their actions. We predict that male mallards will be adjacent to a female when performing a down-up because a broadside position to a female signals courtship while a facing position to a male signals aggression (Mckinney, 1992). The positioning of mallards during courtship behavior is one of the most important aspects to observe and record because they are imperative to understanding the purpose of the signal.

Observations and recordings of the mallards began on September 7th, 2016 and continued for twelve weeks on the campus of Michigan State University, specifically on north and south banks of the Red Cedar River at the rapids behind Wells Hall. Mallards were observed in a highly concentrated area of wildlife that contained both ducks and geese; the geese were ignored as to focus concentration on the mallards. Both sides of the river were utilized in order to obtain stronger observations of the mallards on both river banks. The ducks that were a part of the study were domesticated due to their constant exposure to humans and did not show signs of retreat when observers approached. Observers sat 6 feet from the edge of the water and the communication and interaction was recorded from the side of the river, a distance far enough so as not to interfere in the actions of the ducks. Population of ducks varies depending on the day between approximately 20 and 40 birds with various standard deviations.

For purposes of this study, the various courtship displays are abbreviated.The following abbreviations were used to simplify note taking during observations: 1) HUTU signifies head-up-tail-up; 2) GW signifies grunt whistle; 3) DU signifies down-up; 4) HF signifies head-flick. When a "bout" of mallards is mentioned, this defines a mallard performing a group of two or three behaviors in succession. An example of a bout observation is when a female is actively swimming or nod-swimming, a male may perform many different courting signals in a bout. When a mallard is "broadside" it means that it is next to, or adjacent to another mallard, usually a male and female are seen in this position when courting.

Recordings were made with the camera app on an Apple iPhone and notes were taken in a notebook. When the iPhones were not being used for observation, they were consistently kept turned off so as not to be disturbed. The playback portion experiment was preceded by the audio recording of a male mallard duck performing a grunt-whistle at the Red Cedar River. An Apple iPhone and selfie stick were used for this recording. The selfie stick was held over the water from the edge of the river for 10 minutes which gave ducks time to carry on with their actual behavior if they were to see the selfie stick. The iPhone camera recorded audio for the entire 10 minutes to obtain the clearest mating call. Once this call was obtained the unneeded audio was cropped so a single sound on repeat could be played for playback experimentation. The selected sound was played back with a Bose Soundlink bluetooth speaker. The speaker was placed 2 inches from the edge of the river. Researchers stood at least 20 feet away when the sound was played. The mallard call was played on a set of intervals, each 30 seconds apart and the high level of volume is set constant each time the sound is played.

On the days of observation the initial amount of ducks present in the river were noted in lab notebooks. It was also noted if the males were on one side of the river and if the females were on the other bank. The different variables measured when courtship behavior was seen were: (1) the position of the male duck; if it was broadside which signifies courtship, or if it was facing the female which would then suggest aggressiveness; (2) the distance between the two ducks; (3) and the orientation of the duck if they were in the down-up position or head-up-tail-up (Davis, 1997). It was also taken into account if the mallard ducks would have any communication such as the grunt whistle and if the grunt whistle came before or after the down-up behaviour. This was observed to see if there is a direct correlation between the two characteristics. Because gender is so easily distinguishable in mallard ducks, the sex of the duck will be recorded with every display. The data was collected by recording with an iphone.

In order to measure the distance mallards were from each other, an application called Cam-Measure was downloaded onto an iPhone and used. A picture was taken using the application if the ducks were seen showing behaviors of courtship and the distance between the ducks as well as the orientation (position from point of reference) would be recorded. The application allowed for determination of how far two objects were apart from each other without having to be next to them with a measuring tool. The measurements would be given without having done any observation and could be recorded into a histogram.

Observation sessions took place periodically through the week. Each observation session was an hour to two hours long depending on the population of ducks present. During each observation session the observer would have a selfie stick which would hold their phone for video recording. A Bose speaker was placed near the bank of the river playing an authentic grunt whistle which was used as a playback in the experiment to see if the grunt whistle would cause any change in behavior. The location of observation was behind Wells Hall where the mallards usually abide and near the rapids. The observer was required to adjust their position and move along with the ducks if they swam down the river but they stayed disguised and unobvious as a precaution to the ducks becoming frightened and swimming away. Observers would often hide themselves behind tall bushes and trees.

To make connections between human courtship and mallard courtship derived from the shared DRD4 gene, observations were performed of humans. Notes and video recordings were used and permission from the observed specimen was taken after the observations and iPhone video recordings were completed. Behavioral patterns such as muscle flexion, hand placement and possible affirmation of a smile were observed in the male subject (Scheflen, 1965). The female subject's responses to certain male courtship patterns were recorded. The female generally responds with gestures such as nodding and tilting of her head, leaning into the male, and smiling (Givens, 1978). Human observation sessions were varied; observation areas included Brody cafeteria, Holmes cafeteria, MSU main library, MSU football games, tailgates, and Los Tres Amigos restaurant.

The data collected with how many ducks were present during each observation was noted in a lab notebook and the average number of ducks was transformed into a graph. Recording the number of male and female ducks present helped in understanding if the amount of ducks present during each observation had any effect on mating behaviors. The number of ducks that would show a specific behavior such as grunt whistle, down up and head-up-tail-up would also be noted in a lab notebook and the average would then be found by dividing that number by the total number of ducks present that day. A picture of the orientation of the duck would taken and then be made in microsoft word with how far the duck was orientated from the point of reference.

In the early stages of research, predictions were made regarding specific behaviors, frequencies of behaviors, and positions of behaviors. These variables were then observed in the natural habitat and tested for accuracy using a chi-squared test, A chi-squared test showed whether there was a significant association between two tested variables using expected and observed data. The association between gender and behavior was calculated for all six observed behaviors. In order to perform a chi squared test, there were two categories (gender and behavior) and it was taken from a random sample because the mallards present on any given day are a random sample of the entire population of mallards. To perform the chi squared test, the degrees of freedom were determined to be 5, and expected frequencies and observed frequencies were calculated. An alpha value of 0.05 was used to test the probability associated with the found test statistic. In addition to performing chi-squared tests to assess association, t-tests were done in order to test if the mean of groups were statistically significant. For example, if the means of males performing a down-up was statistically significant from the mean of females performing the down-up. The t-test was performed by calculating the difference between the mean of two related groups (i.e. means of males or females performing down-up), and dividing it by the standard error for the differences. Using this calculated t-value, the degrees of freedom, and alpha value (0.05), the means of the two groups were tested for statistical significance.

During the hours of observations specific behaviors were linked to certain species and sexes. Mallard males were associated with the head-up-tail-up, down-up, and grunt-whistle. Female mallards demonstrated the swim-shake, nod-swim, and head-flick. On each of the days of observation, the amount of male and female mallards present was roughly the same which allowed for less behavior representing competition and more representing courtship (figure 1A). This also allowed for an accurate tally of when the male mallard ducks were facing the female, a sign of aggressiveness and when the male was broadside to the female, a sign of courtship (figure 1B). Humans, on the other hand, performed their own sets of behaviors. Males primarily flexed their muscles, had erect posture, and longer eye contact. Females primped their hair, laughed, leaned in, and tilted their head.

Many statistical tests were performed to analyze observational data collected from mallards and humans. For mallards, the “T-test” using an alpha value of 0.05 tested whether the means of two groups are significantly different. These tests conclude that the p-values for down-up is 0.0095; the head-up-tail-up is 0.0031; grunt whistle is 0.0078; and nod-swim are 0.0012; showing statistical significance. This means that for each of these behaviors the means of females and males performing are different. T-tests for head-flick: p-values of 0.062 and swim-shake: 0.122, respectively, proved insignificant, meaning that both males and females perform this behavior. Certain behaviors are specific to males and for females but some are used by both species which means that these behaviors may not be directly related to attraction of a mate (figure 2). In addition, for each of the three male-specific and male initiated behaviors, the broadside positioning was observed in every case of the signal being performed except once (figure 3). For male and female humans, t-tests showed that only hair primping: 0.0098; muscle flexion: 0.0183; and head-tilting: 0.0062 proved significant with p-values less than 0.05. This shows that these behaviors are specific to either males or females (figure 4). Behaviors such as eye contact, hand placement, and erect posture proved insignificant with large p-values of 0.102, 0.078, and 0.082 respectively, showing that these behaviors were performed by both sexes.

A chi-squared statistical test showed the association between sex and a certain behavior. Statistically significant results showed strong evidence that a certain sex would perform a certain behavior. For male mallards, tests produced p-values for the head-up-tail-up: 0.00023, Down-Up: 0.00042, and grunt-whistle: 0.00321 that were statistically significant, showing that there is a correlation between sex and these behaviors. For female mallards the nod-swim was the only statistically significant behavior using the chi-squared test. Behaviors not strongly associated with either sex of mallards were the head-flick (p-value of 0.012) and swim-shake (p-value of 0.236). Chi-squared tests also show association between sex and behaviors for humans. For males, muscle flexion (p-value of 0.00023) was the only behavior strongly associated with the male sex, and females were statistically associated with primping (p-value of 0.00325) and head tilting (p-value of 0.0013). Eye-contact, hand placement, and leaning in were not found to be specific to either sex so it was concluded that they are used by both sexes in courtship.

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Figures

Authored By: A51245222

a.) b.)

Figure 1. Population of Ducks Recorded Through Observing Period. A.)The number of female and male ducks present were recorded through the observing period. An initial count of the bout of ducks was taken every single time an observer sat down and observed. It was rarely observed when a duck was leaving. However, ducks would fly in and join the bout already present in the river. Whenever this occurrence took place, the amount of ducks in the river was recounted continuously. This was done to see if any of the females that were previously not mated would be attracted to the new males that flew into the river. At the end of each observing period the average number of female and males ducks was then recorded in the graph above. In the histogram above the orange columns represent the number of males and the blue columns represent the number of females observed that day. B.) When a male and female duck were seen in close proximity the observer would note down if the male was broadside to the female or facing the female. Research done by Ellen Davis showed that is the male was facing the female then it was aggressive behavior while if the male mallard duck was broadside to the female it would be considered courtship behavior.

Authored By: A51245222

Figure 2. Average number of mallards performing six different courting signals. Male and female mallard ducks were observed for a consecutive period of ninety minutes, twice a week, for five weeks and their actions were recorded. The six actions being specifically observed were the head-up-tail-up (HUTU), down-up (DU), grunt-whistle (GW), swim-shake (SS), head-flick (HF), and nod-swim (NS). The blue bars represent the behavior of the male mallards and the red represent the behavior of the females. The average number of mallards performing a signal was used rather than the raw number observed because if there are more mallards present on a specific day, the data would be otherwise skewed. Standard error was calculated for the means of each category in order to determine if the differences in means were statistically significant. Out of the total sample size of 48 males, the male initiated behaviors HUTU, DU, and GW had average percent of 64.6%, 35.4%, and 31.3% respectively and of the sample size of 32 females, these three behaviors had averages of 6.2%, 3.1%, and 0%, respectively. The predicted female response behaviors SS, HF, and NS had average female performances of 21.8%, 34.3%, and 65.6%, respectively while the averages of males performing these were 10.4%, 14.5%, and 2.1%, respectively. As predicted, males were more likely to perform the courting signals GW, HUTU, and DU more than females and females were more likely to perform the response behaviors of HF and NS more than males. However, the SS was performed largely by both sexes which leads to the conclusion that it is not a gender-specific behavior during courtship.

Authored By: A51245222

Figure 3: Body Orientation of a group of male mallard ducks following one lone female mallard duck. The data was observed on October 9th, 2016 at 2:30pm in the Red Cedar River in East Lansing, MI. This data was collected strictly by observation on the south side of the river 15 feet from the edge. The scale of 2 feet was collected using the reference of a length of a duck (20-26 inches) and comparing the space inbetween the leading mallard and the female mallard. This observation lasted 5 minutes and 15 seconds only to be disturbed by a human throwing bread to other ducks nearby. Before the formation dispersed, at 3 minutes the leftmost male mallard in the row furthest from the leader left the bout for reasons unknown. The males' swimming patterns were contingent on the female's swimming direction. This body orientation is an example of how each bout often has a dominant leading male whom regularly shows a mating display such as a down-up, head-up-tail-up, or a grunt whistle.

Authored By: A51245222

Figure 4: Average number of humans performing courting signals. Fifteen male and and fifteen female humans were observed in multiple locations. Their behavior and actions were recorded. The courting signals that were recorded were eye contact, muscle flexion, hand placement, posture, primping, and head tilting. The green bars represent actions by males and the purple bars represent actions by females. Out of a total of fifteen males, 93.3% made eye contact, 66.7% showed muscle flexion, 46.7% showed a distinct hand placement, 53.3% had a posture that showed courting behavior, 6.7% showed primping, and 13.3% showed head tilting toward each other. Out of a total of fifteen females, 80% made eye contact, 0% showed muscle flexion, 33.3% showed a distinct hand placement, 66.7% had a posture that showed courting behavior, 86.7% showed primping, and 80% showed head tilting toward each other. Males showed eye contact and muscle flexion at a much higher percentage than females, and females were much more likely to respond with primping or head-tilting. Hand placement and posture did not test to be associated significantly with either sex, so they are concluded to be used by both.

Figure 5: Mallard Duck Behavior. A five minute documentary was made on Mallard courtship behavior. The video starts off with a short tour of Michigan State University. Then the video gives a brief description of what courtship is and then states the research project assigned. There are various clips of the mallard ducks and humans. With each clip there is a voice over explaining each scene. There is also soft background music playing in the back throughout the entire movie to keep the audience engaged. Towards the end of the movie credits are given to important people and ends with the campus of Michigan State University yelling go green, go white.