Symposium 2004

Monitoring Avian Productivity and Survivorship (MAPS) is a program designed to measure the population of birds in an area, and to monitor this population. It also attempts to figure out why and how that population changes. The MAPS program has been in session for the last two summers in two locations at Merry Lea, a nature preserve in Northern Indiana, located about half way between Goshen and Fort Wayne. MAPS records a large amount of information about each bird including its species, the age, sex, brood patch, cloacal protuberance, fat, body and flight molt, flight feather wear, juvenile plumage, wing length, weight, and net number of where the bird was caught. Each bird is banded and then released. The results of this study are from the 373 birds caught this past summer of 2003. The results of this year are compared to those of last year. The results of each location are also compared. The researchers doing this particular MAPS study also noticed many behavioral patterns in particular species, some of which would not be discovered from only looking at the raw data. Apparent conclusions were also made from the above comparisons, but no concrete conclusions can be made until there is more data from future years and future locations. 

1. Introduction

Monitoring Avian Productivity and Survivorship (MAPS) is a study of landbirds during breeding season. It was created in 1989 by The Institute for Bird Populations (IBP). It is the first program to provide data on the demographic parameters and productivity and survivorship of landbirds (DeSante et al. 2002). Before its creation there were other programs that calculated bird populations but they did not give data on demographic parameters or vital rates. This data is important in determining causes of population change and in identifying management actions that need to be taken in order to reverse population declines (DeSante et al. 2002). MAPS is a nation wide program has grown to over 500 stations by the year 2000. All of the data collected is sent to IBP, who then processes it in order to learn the productivity and survivorships of landbirds in relation to the demographics.

            Those involved in MAPS programs are expected to follow certain codes of ethics in dealing with the birds. Each person is to abide by The Bander's Code of Ethics. This states that banders are responsible for the safety and welfare of the birds so that stress and injury or death is minimized. Work is to be continually assessed in order to make it possible to change methods if injury or mortality occurs. Workers are to assess one another and themselves to help maintain the highest standards possible. It is to be ensured that data is accurate and complete. Also, permission to band must be obtained where authorization is required. (North American Banding Council, 2001) A complete copy of The Bander's Code of Ethics can be found in The Instructor's Guide to Training Passerine Bird Banders In North America, a product of the North American Banding Council.  

MAPS also has several protocols that must be followed. The program begins in mid-May and continues through mid-August. There are a total of eight sessions for each location. Each session takes place during a certain period provided by IBP and must be at least six days apart from each other.  Refer to Table 1 for the particular periods and dates the bird banding was scheduled for. Some of these dates may be different from the actual bird banding dates due to rescheduling because of poor conditions, i.e. rain or wind. Each location should have ten nets, although it may be necessary to have fewer if there are not enough personal to work ten nets efficiently. The nets are opened at sunrise and left open for six hours. All nets are checked every half hour.

 

Table 1 the periods and dates scheduled for bird banding

 

 2. Materials and Methods

 

The materials used for successful bird banding are listed below:

 

10 mist nets (12-meter, 30mm mesh, four-tier, black, tethered, nylon)

40 ½ inch conduit poles

40 Stakes

10 Raisers

Rope

Bird bags

Clothespins (Numbered 1-10)

Crochet Hooks

Bands (sizes 0-3)

Device to measure the bird leg for a certain band size

Band Pliers

Ruler (cm)

Weighing device (grams)

 

2.1 net setup

 

A net is strung between ½ inch conduit poles. Two poles are fitted together at each side of the net, making one long pole at each side. These poles are tied to stakes with rope and stuck into the ground to keep them tight. See Figure 1. The net is set up the day before bird banding and the mist net is tied closed with rope and raised up to the top of the poles. This way all the nets can quickly be opened at sunrise the next morning.

 

Figure 1 A properly set up mist net.

2.2 extracting birds from nets

The most important thing to determine when taking a bird out of a net is the way that the bird flew in. It is almost impossible to be successful if the wrong way is chosen. There should be a hole somewhere that is larger than the size of the holes in the mist net, although this can be extremely difficult to find. It is usually best to extract the feet from the net first, then the wings, and finally the head. Once free from the net, the bird is carefully placed in a bird bag and taken back to the site. The bag is marked with a clothespin with the number of the net the bird came from. This is important for recording accurate demographic information. A bird should be released within the vicinity of the net it was caught in because birds are territorial and may be attacked by other birds if released in the wrong area.

 

2.3 recording data   

 

All data is recorded on a MAPS BANDING Sheet. This includes the bander's initials, band size and band number, species name and alpha code, age and how aged, sex and how sexed, brood patch (BP), cloacal protuberance (CP), fat, body molt and flight feather molt, flight feather wear, juvenile plumage, wing length, weight, and status of the bird. At this station very few birds had any body molt or flight feather molt because it was not late enough in the season for molting. Also recorded is the date, time of capture, net number, and location. A note number may also be added if the bird escapes or has a deformity. The note is recorded on the back of the sheet. A full description of how to identify, age, and sex specific species can be found in Identification Guide to North American Birds by Peter Pyle.

 

2.3.1 banding

 

The bird should be held so the head is between the index and middle finger with the body on the palm of the hand. In this way the bird cannot escape easily and all the features of the bird can be seen. The band is placed on either leg with the banding pliers. The leg can be measured with a device to determine the size of band.

 

2.3.2 ageing

 

Birds can be aged as hatching year, after hatching year, second year, after second year, third year, and after third year. At this MAPS station, hatching year birds through after second year bird were identified. Some birds molt all of their greater covert feathers but not the primary coverts after their first year. Therefore, if the primary coverts are different from the greater coverts, the bird is in its second year. If all the feathers are uniform then the bird is an after second year. Similarly, some birds don't molt all of the greater coverts after their first year. These also can be identified as second years. See figure 2. However, some birds molt all their covert feathers after their first year so they can only be identified as after hatching year. Hatching year birds have at least some juvenile plumage.

 

2.2.3 sexing

 

The sex of a bird can often be determined through plumage, the patterns on the feathers. The males are usually more colorful than the females. If plumage is similar, the sex can sometimes be determined by the brood patch (BP) or cloacal protuberance (CP) during breeding season. The presence of a BP suggests that the bird is a female because they lose feathers on their chest when they sit on the eggs. However, some males also brood and so signs of a BP. Only males have large CPs, although some females show signs of small ones. Gently blowing the feathers on the underside of a bird will uncover a BP or CP if it exists. The texture of the BP and the size of the CP are also recorded. 

 

2.2.4 determining other data 

 

Fat is found underneath the wing, right at the top, where the wing connects to the body. If fat is present, it is found a group of muscles in that location that can be seen by blowing on the feathers. Fat shows up as little yellow spots on the muscle.

Flight feather wear is determined by looking at the remiges (see figure 2). The range is from 0 to 3 with 0 being no wear and 3 being largely significant wear. Signs of wear are cuts in the feathers and broken feathers.

Wing length is determined using a centimeter ruler. The ruler is placed under the wing and measured from back to tip. The wing should lie naturally, and not be pressed down flat.

            The bird is weighed inside its bird bag. The bag is first zeroed on the gram scale and then the bird is placed inside the bag and weighed with the bag. This is done last as to minimize the amount of times the bird is taken in and out of the bag and therefore minimize stress on the bird.

 

Figure 2 Diagram of a bird wing.

 

3. Results

 

The total number of species caught this year was 39. Thirteen new species were caught this year while only four species that were caught last year were not caught this year. The total number of new captures was 291 and the number of recaptures was 82, making the grand total 373 birds. Table 2 shows the number of new captures and recaptures of the ten most popular birds, that is the bird caught most often. Song Sparrows were the most popular birds with a total of 97, while Grey Catbirds were a close second with a total of 81. Field Sparrows, Northern Cardinals, and Common Yellowthroats were all in the thirties. Yellow Warblers were in the twenties, while American Goldfinch, Red-winged Blackbirds, and Brown-headed Cowbirds all ranked last in the teens. 

Table 2 the number of birds captured this season

Species	New Captures	Recaptures	Total
American Goldfinch	15	1	16
Brown-headed Cowbird	13	2	15
Common Yellowthroat	21	10	31
Field Sparrow	29	7	36
Grey Catbird	59	22	81
Indigo Bunting	17	5	22
Northern Cardinal	29	6	35
Red-wing Blackbird	15	1	16
Song Sparrow	73	24	97
Yellow Warbler	20	4	24
Total #of birds	291	82	373

 

 

 

3.1 comparisons with last year

 

Graph 1 shows the number of new captures this year in comparison with the new captures last year. This year ten nets were run while only seven nets were run last year.  Therefore, it can be assumed that more birds would be captured this year because of the greater number of nets. This was taken in account for by not counting the birds from nets eight, nine, and ten, and those results are represented in the white bar of the graph. With this accounted for, most species had similar numbers caught both years. The exception to this is the Song Sparrow, whose number doubled this year, and the Grey Catbird and Yellow Warbler, whose number is significantly lower than last year.

 

Graph 1

 

3.3 net comparisons

 

Graphs 2 and 3 show the number of birds caught in each net at each location. At the MLFS location net seven caught the most birds and nets five and ten caught the fewest. At the MLWM location nets five and ten caught the most birds and net six caught the fewest. Nets eight, nine, and ten at MLWM make up for over a third of the birds whereas nets eight, nine, and ten at MLFS make up for less than a fourth of the birds.

 

                                                    Graph 2                                             Graph 3

3.4 difference in locations

 

Graph 4 illustrates the difference in type and number of new captured species between the two locations, MLFS and MLWM. The blue and green bars represent last year while the red and yellow bars represent this year. Respectively, blue and red represent MLFS while green and yellow represent MLWM. For the most part, similar amounts of species were caught in both locations both years.  There are a few exceptions to this. American Goldfinch and Red-winged Blackbirds were caught mostly at MLFS, while House Wrens and Rose-Breasted Grosbeaks were caught only at MLWM.

 

Graph 4

 

3.5 difference in time of year

 

Graphs 5 and 6 reveal the difference in the time of year in relation to how many total birds were caught each day. Graph 5 represents the year 2003, while graph 6 represents 2002. The blue line is the mark for MLFS, where as the green line marks MLWM. The red lines connecting the blue and green points show which two dates belong in each period. Both years both the blue and green lines are highest at the very beginning and slowly decrease as the year continues. However, each graph also shows that both lines jump back up near the end of the season. The 2002 graph's lines decrease again ending at the last two points. The 2003 graph's last two points are the increased jump discussed prior. However, the data for the 2003 graph is not yet complete because there is still one more period left in the season. If that period's results also cause the lines to slope down, then it will follow the pattern of the 2002 graph. There is one significant difference between the two graphs. In 2003 each period's points are fairly close together, meaning that similar numbers of birds were caught at both sights within each period. In contrast to that, in 2002 the MLWM line is almost always lower than the MLFS line.

 

 

 

 

 

 

 

 

 

Graph 5

 

Graph 6

 

4. Discussion

 

There were many observations made by the researchers performed this particular MAPS study. These observations were mostly behavioral patterns seen in the birds that may never be revealed by only using the results of the recorded data. They were seen specifically because the researchers were watching and handling the birds and therefore noticed particular patterns. They cannot be considered sound research results, but that does not diminish their validity.  Part of the goal of the MAPS project is to understand how these birds live and behavioral patterns is obviously part of that. Therefore, these observations are included in this paper as speculations. However, if more direct research measures are taken to further the evidence in the future, these mere speculations may be considered a possibility of actual bird behavior.

Time and time again a pair of the same species, one male and one female, were found in the same net at the same time. This suggests that some birds mate fly together. In addition, a pair of recaptured Field Sparrows was found in the same net at the same time. When their bands were checked it was discovered that the year before they had both been caught in that same net, on the same day, and at the same time. This gives further evidence and adds that some birds may even stay together as mates for longer periods of time, and perhaps their entire lives.

            It was noted several times that Song Sparrows get caught in the one net, six or seven at a time. This suggests that these species fly close together in groups because they all seemed to get caught at once. Also, sometimes a group was caught in both sides of the net. This presents the idea that perhaps some birds of the group flew into the net and the ones that didn't get caught turned around and flew back to help the others. This has also been found in other species. Furthermore, occasionally while a bander was attempting to free a bird from the net, another bird of the same species would fly in. The assumption here is that the second bird was responding to the first bird's distress call.

            Once a male Cardinal was captured in a net with three juvenile Cardinals. This suggests that this was a family, and the father was teaching his children how to fly, or, at the very least, watching out for them. The question that comes up is, where was the mother? This was not found in any other instances, but it would be interesting and beneficial to do tests to discover if these birds were related, and also to watch for similar cases in other species.

            It was very evident to all of the researchers present that birds have very distinctive personalities. There were often birds captured that were the same species, sex, and age and yet acted very differently from one another. One would be calm and very still when handled and another would be very loud and aggressive. Some species were also more likely to be more aggressive then other species, such as Cardinals and Cowbirds, but it is the opinion of these researchers that the personality was the determining factor much more then the species was.

 

5. Conclusions               

 

It must be first stated that in order to have concrete conclusions it is necessary to either have many years of data in a row or many different locations, or both. Two years of data with only two different locations is not at all sufficient for any concrete conclusions. However, there were some apparent conclusions from comparing the two years and the two locations. If further data from years to come supports these conclusions it may be possible to state something concrete. However, it is just as likely that future data will contradict them.

            When comparing the different years it is apparent that the number of new captured Song Sparrows is much greater this year. The number of Catbirds and Yellow Warblers is significantly below what it was last year. Other species numbers have remained relatively the same.

            Comparisons of the different nets show that some nets have a much higher percentage of birds caught then other nets. The reason for this is unknown, although it has been speculated that the nets with the highest percentage are located in woodland areas with lots of vegetation, making them harder for the birds to see. It is also important to note the difference between nets eight, nine, and ten at both locations. It is believed that there are a greater number of birds at the MLWM location this year due to the good location of these three nets.

Comparing the different locations suggests that they are indeed different enough from each other to have different species in those areas. Red-winged Blackbirds and Goldfinches are found mainly at the MLFS location. In contrast, House Wrens and Rose-breasted Grosbeaks were only found at the MLWM location. Also, there was greater species diversity in 2003 at the MLFS location. However, this is different from 2002, where the species diversity was the same at both locations. However, since many species were found in similar numbers in both locations, it can be assumed that the locations are fairly similar.

 Birds are more active during the beginning of the breeding season because it is then that they are mating, and foraging for nesting materials and food to feed their young. This is the apparent conclusion for why a much greater number of birds are caught at the beginning of the MAPS program. As the season continues the activity of the birds goes down and less birds are caught. This number jumps back up at the end because of the number of juvenile that are now actively trying out their wings. The green line is lower then the blue line in 2002 because fewer birds were caught at the MLWM location that year. The lines are close together in 2003 because similar amounts of birds were caught in both locations. This is again believed to partly be because of the good location of nets eight, nine, and ten at the MLWM location. 

 

6. Acknowledgements

 

The author wishes to express her appreciation to all fellow bird banders: Dr. David Miller, Justin Welty, Katie Mast, Freya Berntson, and Jason Kauffman.

 

 

References

 

[1] DeSante, David et al. MAPS Manual: 2002 Protocol. California: The Institute of Bird Populations, 2002.

[2] Field Guide to the Birds of North America, 3rd edition. Washington DC: National Geographic Society, 1999.

[3] Instructor's Guide to Training Passerine Bird Banders In North America, The. California: The North American

Banding Council, 2001. 

[4] Pyle, Peter. Identification Guide to North American Birds. Calfornia:Slate Creek Press, 1997.

[5] Sibley, David Allen. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knoph, 2001.