Dates and numbers of migratory return of territorial and non-territorial male and female Wilson's Warblers
Data files
Oct 30, 2024 version files 91.08 KB
-
Data_File_1.xlsx
13.88 KB
-
Data_File_2.xlsx
13.82 KB
-
Data_File_3.xlsx
13.93 KB
-
Data_File_4.xlsx
13.93 KB
-
Data_File_5.xlsx
13.96 KB
-
Data_File_6.xlsx
14 KB
-
README.md
7.57 KB
Abstract
Early migratory return for territorial passerines is important, since earlier return results in better territories, and greater reproductive success. Many passerine studies have found that migratory return dates for first-breeding-season (SY) individuals was a week or less later than for older (ASY) birds. Many of both ASY and SY birds in these studies became territorial, although more SY than ASY birds became non-territorial floaters. In this study of Wilson’s Warblers, however, nearly all individuals returning early and becoming territorial were ASY birds, and very few were SY birds. However, second waves of returning Wilson’s Warblers, containing both SY and ASY birds, returned about three to five weeks after the first migratory waves, and no males in these second waves ever became territorial. No later-returning, second-wave female initially ever became territorial either, although some subsequently became replacement mates for earlier-returning males. Some male Wilson’s Warblers were territorial, and others were non-territorial, during all of their study-area years. However, some males switched status over successive years, and migratory return when non-territorial, always was several weeks later than when territorial. Findings from this study indicated that, for some males during some years, non-territoriality was more adaptive than was territoriality. This study’s finding, of three-to-five-week later migratory return waves for non-territorial, than for territorial, Wilson’s Warblers, supports findings by Stewart (1973), that Wilson’s Warblers return to breeding grounds in two migratory waves. Findings from both studies may provide empirical evidence supporting Kokko’s (1999) hypothesis, that migratory birds not competing for territories should return to breeding grounds later, on their “cost-minimizing dates.”
Brief summary of dataset
The basic purpose of the paper, of all graphs and tables, and thus of all data files, is to compare the migratory arrival of territorial versus non-territorial Wilson’s Warblers.
Description of the data and file structure
This dataset contains six data files, used to formulate all graphs and two of four tables in the paper. All DRYAD data files have the same structure, that is, four columns, A, B, C, and D, and the same number of rows, 1 to 60.
Column A gives the date of observations.
Column B gives the order of those dates, that is, the first date on which relevant observations were made was 11 March, and this is ordered #1. Twelve March is ordered #2, etc. Nine May is ordered lastly at #60.
Column C states the number of territorial Wilson’s Warblers seen on the date stated in column A.
Column D states the number of non-territorial Wilson’s Warblers seen on the date stated in column A.
While all data files have this same structure, they differ in specifics of the recorded data, such as migratory arrival dates, whether data was for males or females, the number of birds that were considered, and/or whether birds were banded or unbanded. For example, data file #2 shows total numbers of territorial females that were recorded arriving between 15 March through 28 April, and total numbers of non-territorial females that were recorded between 14 April and 9 May. However, data file #4 considers only five territorial males arriving between 11 and 21 March, and five non-territorial males arriving between 6 and 25 April. Although actual sightings of Wilson’s Warblers on specific dates were relevant, the numbers sighted on other dates always were listed, whether any birds were seen or not. In other words, many dates in the files recorded zero sightings. No dates in the data files were left blank, and there was no missing data.
Specifics
DATA FILES 1 AND 2
I used data files 1 and 2 to produce Graphs (Figs.) 3a and 3b in the paper, which are plots of migratory arrival for territorial and non-territorial Wilson’s Warbler males and females respectively. I also used data files 1 and 2, with slight adjustments explained in METHODS, to determined the mean dates of migratory arrival stated in Tables 1a and 1b, which give the mean migratory arrival dates respectively for male and female Wilson’s Warblers. In data files 1 and 2 I state the dates that I saw respective numbers of male and female Orange-crowned Warblers during each day, cumulative for all study years, from 1997 through 2010, excluding year 2000, starting on 11 March and ending on 9 May. The purposes of graphs (Figs.) 3a and 3b, and of Tables 1a and 1b, and thus the purposes of data files 1 and 2, are to compare the migratory arrival dates of territorial and non-territorial Wilson’s Warblers.
Data file #1, used for plotting male arrival in Fig. 3a, and for calculating mean male migratory arrival dates in Table 1a, shows that newly-arriving territorial male Wilson’s Warrblers were sighted from 11 March through 16 April. Newly-arriving Non-territorial males were sighted starting on 5 April, and the last non-territorial male was assumed to have arrived on 9 May. The reason the exact final date for non-territorial arrival could not be determined, and had to be approximated, is that non-territorial males and females did not establish breeding territories, and establishment of breeding territories was the basis of determining arrival times for territorials. The basis for estimating the final arrival times for non-territorial males and females is explained in the paper’s METHODS.
Data file #2, used for plotting female Wilson’s Warbler arrival in Fig. 3b, and for calculating mean migratory arrival dates in Table 1b, shows that Newly-arriving territorial female orange-crowned Warrblers were sighted from 15 March through 28 April. Non-territorial females were sighted starting on 14 April, and the last non-territorial female was assumed to have arrived on 9 May.
IMPORTANTLY, DATA FILES 1 AND 2 SHOW A SECOND COLUMN, FOLLOWING THE DATE COLUMN, TITLED DAY. THIS COLUMN STATES THE ORDER OF THE DATES OF MIGRATORY ARRIVAL. (e.g., 11 March is #1 in the order, and 9 May is #60, and last, in the order.). I USED THESE ORDER NUMBERS, RATHER THAN THE CALENDAR DATES AS SUCH, FOR PLOTTING THE GRAPHS IN FIGS. 3A AND 3B, AND FOR CALCULATION OF MEAN VALUES IN TABLES 1A AND 1B.
DATA FILES 3 AND 4
I used data files 3 and 4 to produce graphs (Figs.) 3c and 3d respectively. The purposes of graphs 3c and 3d, and thus the purposes of data files 3 and 4, were to compare the migratory arrival dates of unbanded non-territorial male and female Wilson’s Warblers respectively with the arrival dates of color-banded non-territorial male and female Wilson’s Warblers. These plots indicate, through inspection, whether or not unbanded non-territorial males (Fig. 3c) and females (Fig. 3d), identified based on their behaviors, had similar migratory arrival profiles as did non-territorial males and females identified based on color-banded greater certainty. Data file # 3 shows that unbanded non-territorial males arrived from migration between 11 April and 9 May, and color-banded non-territorial males similarly arrived between 14 April and 9 May. Data file #4 shows that unbanded non-territorial females arrived between 11 April and 9 May, and color-banded non-territorial females similarly arrived between 5 April and 9 May. As was the case for Figs. 3a and 3b, I used the numerical order of arrival dates in the data files to plot Figs. 3c and 3d, rather than the calendar dates as such.
DATA FILES 5 AND 6
I used data files 5 and 6 to produce Tables 1c and 1d respectively. Data from Table 1c incorporates male migratory arrival dates for the earliest five annually returning territorial male Wilson’s Warblers, compared with the arrival dates for the earliest five annually returning non-territorial males. Data from Table 1d incorporates male migratory arrival dates for Wilson’s Warbler males that alternatively were either territorial and non-territorial during respective years in the study area. The purposes of Tables 1c and 1d, and thus of data files 5 and 6, was to present two additional ways for determining the mean migratory return dates for territorial versus non-territorial male Wilson’s Warblers. These two ways were additional to the mean dates presented for those two subpopulations of males determined in Table 1a .
Data file #5 shows that the five earliest annually returning territorial males arrived between 11 March and 21 March, while the five earliest-returning non-territorial males arrived considerably later, between 26 March and 25 April.
Data file #6 incorporates male migratory arrival dates for males that alternatively were territorial and non-territorial during their tenures in the study area. Data file #6 shows that migratory arrival dates when males were territorial ranged between 21 March and 31 March, and when those same males were non-territorial ranged, considerably later, between 5 April and 9 May. As was the case for data files 1, 2, 3, and 4, migratory return dates in data files 5 and 6 are listed from 11 March through 9 May, and the order of migratory return is indicated as being from 1 through 60. Again, the order of return, and not actual calendar dates, was used to calculate mean values.
Links for sharing and code. - None
Data collected through 13 years of daily observations in the study area during Wilson's Warbler breeding seasons.