Differences in the startle responses among geese in the Wingra Watershed
Heidi Meixner, Amanda Clemens, Jamie Rindy, Jenny Martin
Abstract
Introduction
Methods and Materials
Results
Discussion
Works Cited
Appendix
PDF File
The numbers of urban and migrant geese inhabiting the Vilas Park area of the Wingra Watershed has increased significantly in recent years. We observed the behavioral patterns of the geese to determine if the geese that currently reside in the watershed are migrant or urban based on their startle response to the presence of humans. Once we made this determination, we charted our results to determine if the urban and migrant geese intermingled within the various zones of Vilas Park. We observed the geese on eight different occasions, and recorded the reactions of the geese in each zone. We came to a logical conclusion that based upon their reaction to human presence, over half of the geese we observed were most likely urban while the remaining percentage were most likely migrant. Based upon our assumption we also discovered that both urban and migrant geese did intermingle in two zones of the park. These findings provide information that may aid in promoting the health of the Wingra watershed. We discuss the implications of these findings in the report.
The Wingra Watershed is home to a large number of geese, both migrant and
urban. In recent years, studies have been conducted to determine the numbers of
geese in Vilas Park. According to Jim Lorman, the numbers of migrant geese in
this area have increased significantly since the 1980’s and have become
increasingly adapted to urban and suburban environments such as the area
contained around Lake Wingra in Madison. There are distinct differences in the
behavior patterns of migrant and urban geese, with migratory Canada geese flying
south during fall to their wintering range while the resident geese spend most
of the year in the same general area and fly only far enough to find food or
open water. We also learned that geese display particular movements when they
sense danger. The most common movements in geese are the “alert display”, where
the goose’s head is raised, and the neck is vertical and straight, and the “head
forward display, where the goose’s head is bent low and forward, and can
sometimes be accompanied by a call or a honk (Link 2006). The calls made by
geese can vary from a mild alert call, in which the geese generally do not
perceive any immediate danger and an alarm call, which occurs when geese use a
variety of honks and take flight, usually flying into the safety of a nearby
body of water. Geese who do not appear threatened by the presence of humans and
only emit a single call can be thought to be urban, while geese who tend to let
out a series of honks and then fly away when confronted by humans are more than
likely migrant (Streng 2007).
In evaluating the presence of these geese in the Wingra Watershed, our group
wondered how many of the geese in the park were migrant, and how many were
urban. In making this determination, we pondered if there was a way we could
differentiate between the two groups of geese. With this in mind, we decided to
test the startle responses the geese exhibited when they were approached by
humans to see if we could determine if the geese in the Wingra watershed were
migrant or urban based on their reactions. Once this question has been answered,
we will look at the patterns of behavior between the migrant and the urban geese
to determine if the two groups intermingle within the various zones of the park.
The park has been divided into nine different zones, which lay out the areas
inhabited by the geese on the land surrounding the Vilas park lagoon, where the
geese make their habitat (Figure 1). Our initial study will be to observe the
geese in each zone to determine if they exhibit distinct patterns in their
startle response to humans. Our hypothesis is that we will find differences
between the urban and migrant geese, both in their reactions to humans and the
specific zones in which they are residing. Knowing the differences between urban
and migrant geese will be useful in obtaining information about the numbers of
geese that inhabit Vilas Park on a permanent basis. This information may then be
able to be used to further studies about the influence geese have on the health
of the Wingra Watershed.
Figure 1: Zones in Vilas Park used for determining use of the park by geese
Our testing methods were conducted over a 10 day time period. We observed the geese twice in one day, with the first observation taking place in the morning, and the second in early afternoon (Table 1).
Table 1: Observation dates and timeline
Date Observation 1 Observation 2
|
October 31 |
8:45-9:45 |
11:50-12:50 |
|
November 2 |
8:45-9:45 |
10:15-10:45 |
|
November 7 |
8:45-9:45 |
11:45-12:20 |
|
November 9 |
8:45-9:45 |
10:45-11:10 |
Before we conducted our research, we created charts to record the data relevant to our study. This information included the zone location, the number of geese present in that zone, and the reactions of the geese at various distances. We limited the number of people observing the geese to two at a time to avoid outside distractions and approached the geese by walking towards them at a steady pace. When the geese gave an indication that they had noticed us, we dropped a beanbag on the ground to mark the place where they gave their first reaction. Indications that the geese had noticed our presence included raising their heads, walking quickly towards the water, giving a loud honk or series of honks, or flying away towards the water. The first beanbag was dropped as the geese raised their heads, and looked in our direction. The second beanbag was dropped when the geese began to walk away from us at a rapid pace, and the third bean bag was dropped at the point where they all walked or flew into the water. We then used a tape measure to measure the distance between where the geese first noticed our presence and when they all gave a visible reaction, i.e. by flying away or moving into the water. We did have several sources of error in this method. In some cases we had to estimate the position of the geese based on landmarks, which prevented our measurements from being 100% accurate. In addition, we were unable to measure the exact distance of the geese as they flew into the water, although from a map of Lake Wingra, we were able to deduce that the distance they were from the shore was always less than 100 feet. We then compiled our data, and graphed our results based on several factors we observed to determine if the startle response in the geese varies between the migrant and the urban geese. These factors include the zones in which the geese were present, the distance they were from us when they reacted to our presence and the numbers of geese in particular zones. (See Appendix A.)
During our study, geese were present in five of the nine zones – Zone 1, Zone
3, Zone 6, Zone 7, and Zone 9. After compiling our data, we were able to
determine that there were definite differences in responses of the geese in the
various zones of the park. During our observations, we counted a total of 455
geese who gave little or no reactions to our presence as we approached, and 339
total geese that did show a significant startle response. We based our findings
on two main factors: the first factor was the intensity of the geese’s honking
and the movement patterns of the geese, and the second factor was the distance
we were in feet from the geese when they showed a visible reaction to our
presence. The geese’s reactions varied from intense honking to no noise at all,
and their movements ranged from the alert head display to flight when they
noticed our approach. When the geese honked loudly and flew away when we were at
a distance greater than 35 feet, we concluded that the geese were most likely
migrant, while the geese who gave no visible startle response as we approached
were most likely urban and conditioned to the presence of humans. On two
separate occasions there were geese present in Zone 1. These geese remained calm
upon our approach, and raised their heads slightly when we were about 50 feet
away. They then walked slowly into the water. On both occasions we were able to
get within 30 feet of the geese before they responded, and they did not seem
started by our presence. We determined that these geese were most likely urban.
In Zones 7 and 9, we were able to get within one foot of the geese. These geese
did not appear to be startled by our approach, however, on two separate
occasions, one or two geese raised their heads as we began walking toward them,
then all the geese began moving slowly, in a circular pattern. On one occasion
in Zone 7, the geese walked quickly into the water. Only one goose in these two
zones honked, and that happened only once, otherwise, the geese did not make any
noise as we infiltrated their group. We determined that the geese in these zones
were urban.
In Zone 3 and Zone 6 we found slightly different results. Zone 3 is an island
located in the middle of the lagoon. We divided this zone into East and West as
it was separated by a pedestrian walkway. In Zone 3 East, the geese varied in
their responses to our presence. On several occasions, the geese raised their
heads and began to honk loudly and quickly moved away, flying towards the water.
We determined that these geese most likely were migrant. However, we also found
groups of geese in this area that did not have a strong reaction to our
presence, and on November 9th, we were able to infiltrate a group of geese that
contained both migrant and urban geese. We determined this based on the way the
geese reacted as we came close to them. The geese divided into two groups – the
first group put their heads up right away and walked very fast towards the
water, while the second group lingered by the edge of the water. From the
geese’s reactions we were determined that this group held geese that were both
migrant and urban. In Zone 3 West, we were able to get within the 35 foot limit
we had set, however, the geese in this zone responded to us with loud honking
and then flew into the water. In this case, using the tool of a distance of 35
feet was not a useful measure in making our determination for whether the geese
were migrant or urban. We found similar results in Zone 6 ( Figures 2, 3, 4 and
5).
Figure 1
Figure 2
Figure 3
Figure 4
We graphed our results to illustrate the distance we were in
relation to the geese when they gave a visible reaction. Based on our
calculations that the geese who gave a startle response at a distance of greater
than 35 feet were migrant, and geese who gave no startle response until we were
in close proximity to them were urban, our results showed that in Zones 3 East
and West, and Zone 6, the urban and migrant geese did intermingle
(Figure 6). Our results showed that of the 784 geese present in the Wingra
Watershed, 58% of the geese present were urban, and 42% were migrant.
Figure 5
Red = Migrant Geese
Blue = Urban Geese
Our hypothesis posed that we would be able to distinguish the difference
between the urban and migrant geese in the various zones laid out in Vilas Park
of the Wingra Watershed based upon their reactions to humans and specific zones
in which they chose to reside. Our results showed that there were distinct
differences among the geese which may help distinguish between urban and migrant
geese that inhabit the Vilas Park area. This information is relevant in
determining if the numbers of migrant geese in this area have continued to rise
and if they have become increasingly adapted to the urban and suburban
environment contained around Lake Wingra in Madison.
When compiling our results, we discovered several sources of possible error that
occurred during our study. The first source of error was that we had two
separate groups recording data and making observations, and the data may have
been recorded differently. Also, because two of the members of our group are no
longer a part of this study, it was difficult to analyze their results as we did
not have the capability to discuss their interpretations, leaving us to
speculate on their data. We also found a possible source of error in our
methods. In Zone 3 W we had difficultly determining whether they were migrant or
urban because of the measurement criteria we used. In this zone, although we
were able to get closer than 35 feet, the geese responded with frequent honking
and flight. In deciding whether the geese were urban or migrant, we used the
measurement criteria of less than 35 feet and labeled the geese as urban.
Some possible implications of our study that may be useful in determining how
urban and migrant geese affect the health of the Wingra Watershed include water
pollution from geese feces, growth of local vegetation, and public sanitation.
The numbers from this study could aid health officials in determining whether
the increase in geese is a threat to the Watershed. The results may be useful
for consideration in future park planning in knowing what zones the geese tend
to occupy on a regular basis. Determining whether it is possible to verify if
the geese were urban or migrant based on their startle responses and whether or
not the two intermingled within the two zones of the park.
Link, Russell. Living with wildlife. (Retrieved from Electronic source on 8 Nov. 2006). http://wdfw.wa.gov/wlm/living/canada_geese.htm
Lorman, Jim. “Giant Canada Geese in the Wingra Watershed: A Preliminary
Report.”
27 May, 2003. (Retrieved from electronic source on 8 Nov. 2006).
http://lakewingra.org/library/docs/1117595700-canada_geese.pdf.
Streng, Luke A. and Whitford, Phillip C. (Retrieved from Electronic Source on 25 Feb. 2007). http://www.pestproducts.com/goose.htm