Post on 04-Jul-2015
Assignment #2 Tutorial for NATS 1550
2
Songbirds in the Autumn
• Hatch-year birds (HY, code 2) were born earlier in the year, usually further north
• Adult or After-hatch-year birds (AHY, codes 1, 5, and 6)
Some species can be aged in the autumn by feather plumage, where the duller plumages are usually the young birds
Some species can be aged in the autumn by the shape of the tail feathers, with immature birds being more pointed (and often more worn).
Most species can be “skulled”, where you look at the degree of ossification (hard bone) in the skull. HY birds are not fully ossified.
Yet another method is to look at the pattern of moult. These Saw-whet Owl wings are being looked at in UV light. Older feathers do not show “pink” whereas new feathers do.
Species Age Sex Wing (mm) Mass (g) Year Month DayJulian Date
Time Captured
AMRE 6 5 54 7.1 2007 5 28 148 150
AMRE 5 5 62 8.1 2008 5 20 141 530
AMRE 5 0 58 7.6 2009 5 23 143 530
AMRE 6 5 58 7.9 2005 5 31 151 530
AMRE 5 4 60 7.7 2010 5 21 141 540
AMRE 5 0 61 7.8 2009 5 22 142 540
AMRE 5 4 62 7.9 2010 5 23 143 540
AMRE 5 4 60 7.8 2010 5 24 144 540
AMRE 5 5 58 7.5 2010 5 24 144 540
AMRE 5 5 54 7.9 2005 5 27 147 540
AMRE 5 4 61 8.4 2008 5 6 127 600
AMRE 5 4 62 8 2008 6 6 158 600
BAOR 6 4 94 39.5 2006 5 11 131 113
BAOR 6 4 94 36.2 2006 5 11 131 113
BAOR 5 4 92 32.9 2010 5 22 142 530
BAOR 5 4 94 36.5 2007 5 22 142 540
BAOR 5 4 92 33.9 2010 6 3 154 550
BAOR 5 5 89 35 2006 5 24 144 550
BAOR 6 4 93 33.5 2006 5 28 148 550
There are distinct periods of migration at banding stations
0
2
4
6
8
10
12
14Fox Sparrow
April October
Fox Sparrow (Ontario)
The duration of migration is something that is studied
0
5
10
15
20
25
30
Lesser Yellowlegs
JuneMay July August SeptemberApril
June
Lesser Yellowlegs (Ontario schedule)
What’s the average?
1. 5,6,7,8,9
• (5+6+7+8+9)/5
• = 35/5
• = 7
2. 1,4,7,10,13
• (1+4+7+10+13)/5
• = 35/5
• = 7
What’s the average?
1. 5,6,7,8,9
• Average = 7
2. 1,4,7,10,13
• Average = 7
• Which is a more variable dataset?
• #2
A bell-shaped curve is known as a “Normal Distribution”.
The passage of birds through a migration station usually follows this pattern.
A narrow distribution represents a shorter duration.
The x-axis is time (date) and the y-axis it the numbers of birds
The peaks are the average on the x-axis
A common statistic to show the level of variability is the standard deviation
• Tells you how tightly all the various numbers are clustered around the mean
• When the numbers are pretty tightly bunched together and the bell-shaped curve is steep, the standard deviation is small
• When the numbers are spread apart and the bell curve is relatively flat, there is a relatively large standard deviation
There are a few early birds (green “tail”) and a few stragglers (red “tail”) and most birds are in between, close to the average (“mean”)
Real data are likely to be imperfect, but still close to the Normal Distribution Model
68% of the values are within one standard deviation of the average (mean), shown in red.
+1SD-1SD +2SD-2SD
95% of the values are within one standard deviation of the average (mean), shown in red plus Green.
Imagine you have determined the following:
• Mean is 262
• SD is 17
• What is the range of dates during which 68% of the birds move through the banding station?
• 262 + 17 = 279
• 262 – 17 = 245
Imagine you have determined the following:
• Mean is 262
• SD is 17
• What is the range of dates during which 68% of the birds move through the banding station?
• 262 + 17 = 279
• 262 – 17 = 245
• Therefore, 68% pass through between September 2 and October 6