Hise, Kolenda, Pitt, St. John 1

Hise, Kolenda, Pitt, St. John 1

Daily Activity Patterns of Birds

Kylee Hise, Olivia Kolenda, Debbie Pitt, Meagan St. John

Biology 251: Introduction to Ecology and Evolution

2 May 2017

Abstract

Birds follow a certain diurnal pattern of caloric intake. There are two well-known trends described: two equal times of activity in the morning and afternoon or the highest activity in the morning followed by a tapering off as the day progresses (Morton, 1967 & Rollfinke, 1990). The purpose of this experiment was to determine which pattern birds in Farmville, VA follow. It was hypothesized that the number of species and total number of birds would gradually decrease as the day progressed, along with an inversely proportional relationship with these parameters and temperature. Data was collected at 9 a.m., 12 p.m., and 4 p.m. for five days, over the span of four weeks. Dominance and heterogeneity were also calculated using Simpson’s and Shannon-Weiner Index respectively. The number of species, total number of birds, dominance, and heterogeneity were correlated with temperature. Data was analyzed using one-way ANOVA tests and simple linear regression. If the results were determined to be significant, Tukey Honestly Significant Difference test was utilized. The effect of time of day on the total number of birds present, were found to not be statistically significant (f=2.107, p=0.164). The effect of time of day on dominance also presented to be in-significant (f=1.99, p=0.179). No results posed to be statistically significant due to variance in the data and sampling size. However, the overall trend that bird activity decreased as the time of day progressed was displayed. There was not a correlation between any parameter and temperature.

Introduction

Birds follow a diurnal pattern of food intake.The three typical feeding times that birds follow is in the morning, noon, and afternoon. Seasonal changes may have an impact on the diurnal patterns at which these birds feed due to migratory species. During migratory times, birds require more energy intake and storage. An example of one of these migratory birds includes the White-crowned sparrow.For white-crowned sparrows, the highest activity is in the morning, followed by the afternoon, concluding with the least amount of activity at noon. The highest peak of activity in the morning is explained because the birds want to replenish their energy that they lost from the previous night. The afternoon peak is described because birds want to consume extra energy before the night ahead. (Morton, 1967).

In contrast, another popular pattern that birds follow may be displayed across a wide aray of species. This pattern explains a high feeding activity in the morning, with a gradual decrease in feeding activity as the day progresses. These patterns are more typical in the winter season due to the nights being colder (Rollfinke, 1990). It is difficult to define all birds’ diurnal feeding patterns since so many different factors may affect the time of their caloric intake. These factors may include availability of food and water, air temperature, and social interactions (Morton, 1967).

To define specifically which diurnal pattern that birds in Farmville, VA follow, and if this pattern is similar to either one of the previous findings of caloric intake of birds, this experiment was conducted. The predictor variables were time of day that the birds were present at a certain feeder and the air temperature. The response variables included total number of birds and total number of species.

Since this study was conducted in March, weather is typically cooler and it was hypothesized that the diurnal feeding activity of birds would be the highest in the morning, followed by a gradual decrease in activity as the day progresses. Along with this, it is also hypothesized that temperature and the response variables would be inversely proportional to one another.

Methodology

Study Area

The Environmental Education Center (EEC), in Lancer Park, at Longwood University was utilized as the study location. From four bird feeders present behind the EEC, the medium-tall feeder, measuring 1.6 meters in height, was selected for observational study. The birds were provided with Wild Bird Feed: Economy Mix.

Data collection

Data was collected on the diurnal feeding activity of birds, focusing on species richness and number of individuals of each species using point counts. During three different times of day (9:00 a.m., 12:00 p.m., and 4:00 p.m.), data was collected for a duration of ten minutes, twice each week for four consecutive weeks. Two observers were present for each time slot. Names of the researchers recording, date, what time interval was being observed, exact start time and end time, and temperature were reported for each session. One tally mark was used to represent when one bird was observed to be approaching the feeder. To provide consistency, if a bird fled the area, followed by returning to the feeder during the ten-minute time interval, another tally mark was recorded.

If a certain species was not known, a picture of that bird was taken so that it could be identified later. The Merlin Bird ID app used in the identification of unknown species (The Cornell Lab of Ornithology, 2017).

Data Analysis

The average of the number different species and total number of birds present at the feeder was calculated for the three time intervals. These results were compared to the time of day and temperature. Dominance and heterogeneity were also calculated using Simpson’s and Shannon-Weiner Index, respectively. These results were compared to the time of day and temperature.

Statistical analysis was conducted using R statistical software program. Specifically, analysis of variance (ANOVA) tests were conducted to determine if the results from each parameter comparison was statistically different between on the three time intervals. Next, Tukey honestly significant differences (Tukey HSD) tests were utilized if the ANOVA tests posed to be statistically significant. Simple linear regression was also utilized to determine if each parameter statistically, significantly correlated to air temperature.

Results

Figure 1. The effect of time of day on total number of species present. The f-value from ANOVA test was 1.292 and the p-value was 0.31.

The greatest number of different species present at the feeder were observed in the morning, 9 a.m. After this, the number of different species gradually decreased. The lowest observed number of species was recorded in the afternoon, 4 p.m. The results did not pose to be statistically significant (f=1.292, p=0.31), although it is possible to analyze the down-ward trend in species activity.

Figure 2. The effect of temperature on number of species present. The R2value of the trendline is 0.0149. The f-value from simple linear regression test was 0.1961 and the p-value was 0.6652.

There is a slight negative correlation between number of different species present and air temperature. As the temperature increased, there was a slight decrease in number of species. These results did not pose to be statistically significant (f=0.1961, p=0.1961), although it is possible to observe the slight negative correlation between number of species and air temperature.

Figure 3. The effect of time of day and total number of birds present. The f-value presented from the ANOVA test was 2.107 and the p-value was 0.164.

The greatest number of total birds present at the feeder were observed in the morning, 9 a.m. After this, the number of total birds gradually decreased. The lowest observed number of total birds was recorded in the afternoon, 4 p.m. The results did not pose to be statistically significant (f=2.107, p=0.164), although it is possible to analyze the down-ward trend in total birds as the day progresses.

Figure 4. The effect of temperature on the total number of birds present. The R2value of the trendline is 0.003. The f-value presented from simple linear regression test was 0.03874 and the p-value was 0.847.

There is a slight positive correlation between number of total birds present and air temperature. As the temperature increased, there was a slight increase in total number of birds. These results did not pose to be statistically significant (f=0.03874, p=0.847), although it is possible to observe the slight positive correlation between total number of birds and air temperature.

Figure 5. The effect of time of day on dominance. Dominance was calculated using Simpson’s index. The f-value presented from ANOVA test was 1.99 and the p-value was 0.179.

The highest dominance was presented in the afternoon, 4 p.m. The lowest dominance was presented at mid-day, 12 p.m. Dominance was calculated using Simpson’s index and is defined so that the value is high when there is one species in high abundance at one time. The results did not pose to be statistically significant (f=1.99, p=0.179), although it is very clear to observe that during the 4 p.m. collection time, the highest dominance was presented.

Figure 6. The effect of temperature on dominance. Dominance was calculated using Simpson’s index. The R2value of the trendline is 0.0304. The f-value presented from simple linear regression test was 0.4074 and the p-value was 0.5344.

There is a slight positive correlation between dominance presented and air temperature. As the temperature increased, there was a slight increase in dominance. These results did not pose to be statistically significant (f=0.4074, p=0.5344), although it is possible to observe the slight positive correlation between dominance and air temperature.

Figure 7. The effect of time of day on heterogeneity. Heterogeneity was calculated using Shannon-Weiner Index. The f-value presented from ANOVA tests was 1.748 and the p-value was 0.216.

The highest heterogeneity was presented during mid-day, 12 p.m. The lowest heterogeneity was presented in the afternoon, 4 p.m. These results are inversely proportional to the dominance index. Heterogeneity was calculated using Shannon-Weiner index and is defined so that the value is low when there is a high amount of diversity present in the population. The results did not pose to be statistically significant (f=1.748, p=0.216), although it is very clear to observe that during mid-day, the highest heterogeneity is present.

Figure 8. The effect of temperature on heterogeneity. Heterogeneity was calculated using Shannon-Weiner Index. The R2value of the trendline is 0.0207. The f-value presented by simple linear regression test was 0.274 and the p-value was 0.609.

There is a slight negative correlation between heterogeneity presented and air temperature. As the temperature increased, there was a slight decrease in heterogeneity. These results did not pose to be statistically significant (f=0.274, p=0.609), although it is possible to observe the slight negative correlation between heterogeneity and air temperature.

Discussion

The hypothesis that there will be the greatest activity, number of species present and total number of birds, in the morning, with a gradual decrease in numbers as the day progresses was supported. The hypothesis that there will be an inversely proportional relationship between temperature and the response variables, number of species and total number of birds, was not supported.

The total number of species and total number of birds present based on time of the day presented to show the overall trend to support the hypothesis. However, the results were not statistically significant (Figures 1 & 3). Birds have a higher chance of being preyed upon during the evening, causing them to forage for food in the morning to avoid predators (Bonter et al., 2013).

When analyzing the effects of time of day on dominance and heterogeneity, the results do not present to be statistically significant. However, the overall trend that the highest dominance is prominent in the afternoon (4 p.m.) is supported (Figure 5). This is due to many cowbirds present during this time. For the duration of the study, 14 cowbirds were present during this time slot. The dominance is also inversely proportional to the heterogeneity. It comes to no surprise that the lowest heterogeneity is present in the afternoon (4 p.m.) (Figure 7). The level of diversity (heterogeneity) decreased as the day progressed due to the high presence of brown headed cowbirds in the afternoon. Brown headed cowbirds avoid predation by travelling in flocks, which in turn has limited the total number of birds at the feeder, decreasing the variation of the community (Thompson III, 1994).

There is also not statistical evidence in the data to support that there is a correlation between temperature and the previously mentioned parameters (total number of species, total number of birds, dominance, and heterogeneity). All correlations present to be almost linear. This may be due to the limited variation in temperature during this study, since it was conducted only in March. However, there is a slight down-ward trend that is present when comparing the number of species and total number of birds to temperature. This is due to when temperatures were cooler, birds were forced to eat at earlier times. From the cold night, they have lost a great deal of energy (Ockendon et al., 2009).

This information allows the avian life forms in Northern America to be better understood and can help humans raise the diversity level. The rise of different species of avian life forms not only impacts humans but also betters the ecosystem.

To expand on this research, collection should be obtained for a longer time span, of at least 30 days, possibly expanding into different seasons. Longer time intervals of data collection could also be expanded to 30 minutes, allowing more time for more birds to appear.

Acknowledgements

This work was supported by Longwood University’s Department of Biological and Environmental Sciences and Dr. Henkanaththegedara.

Literature Cited

Bonter, D., Zuckerberg, B., Sedgwick, C., & Hochachka, W. 2013. Daily foraging patterns in free-living birds: Exploring the predation—starvation trade-off. Royal Society, 80(1760): 1-7.

Morton, L. M. 1967. Diurnal Feeding Pattern of White-Crowned Sparrows, Zonotrichia leucophrys gambelii. American Orinthological Society. 69(5): 491-512.

Rollfinke, B. & Yahner, R. 1990. Effects of Time of Day and Season on Winter Bird Counts. TheCondor. 92(1): 215-219.

Ockendon, N., Davis, S.E., Toms, M.P. & Mukherjee, S. 2009. Urbanization and time of arrival of common birds at garden feeding stations. Bird Study. 56(3): 405-410.

Thompson III, F. 1994. Temporal and Spatial Patterns of Breeding Brown-Headed Cowbirds in the Midwest United States. The Auk.111(4):979-990.