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Tag Deployment

Everything you need to know about deploying tags

Tag Management

This chapter pertains to tag deployment methos in the field. For information on the management of tag deployment metadata withing the Motus system, see Tag Management.

How to tag animals

Instructional videos on how to tag videos can be found in the next section.
We will be updating this section soon. For now, please see our PDF guide: https://motus.org/data/download/tag_deployment_methods.pdf

Trimming tags

There are a number of researchers who opt to cut the antennas of tags when deploying on smaller animals. Basic antenna theory suggests it will decrease the effective power of the transmitter, but more testing is needed to determine the magnitude of this decrease when deployed on animals. Controlled tests have shown that OOK tags (166.380 MHz) will decrease in power with length, but are most effective when cut to specific lengths (harmonics of the nominal frequency). On the other hand, FSK tags (434 MHz) appear to decrease continuously with length, not showing better performance at specific lengths like OOK tags. These tag tests were not done on animals and will likely be different in real deployments.
That being said, if you're planning on trimming one of your Lotek tags, you should aim for one of these lengths to maximize the effect power:
Frequency
Lengths
166.380 MHz
18.0 cm, 15.0 cm, 12.9 cm, 11.3 cm, 10.0 cm, 9.0 cm, 8.2 cm, 7.5 cm, 6.9 cm, 6.4 cm, 6.0 cm, 5.6 cm
151.5 MHz
19.8 cm, 16.5 cm, 14.1 cm, 12.4 cm, 11 cm, 9.9 cm, 9 cm, 8.2 cm, 7.6 cm, 7.1 cm, 6.6 cm, 6.2 cm
150.1 MHz
20 cm, 16.6 cm, 14.3 cm, 12.5 cm, 11.1 cm, 10 cm, 9.1 cm, 8.3 cm, 7.7 cm, 7.1 cm, 6.7 cm, 6.2 cm

Tag Harness sizes

This table lists harness sizes for the pre-fabricated ‘figure eight’ leg loop harness method based on real sizes used on individuals tagged in the field. Sizes include the length of the entire single leg-loop, but do not include overlap with the tag. Weights can be used to help specify which harness size to use.
Please note that these are guidelines. Regardless of what sizes you find here, the harness should always be fitted to the individual. Please see a How to Tag Animals above for more information.
Species
Harness Size (mm)
Weight (g)
Sample size
Yellow-billed Cuckoo
50-61
43-80
10
Black-billed Cuckoo
52
34
1
Hammond's Flycatcher
29
9.5
1
Dusky Flycatcher
34
1
Say's Phoebe
37
23.5
1
White-eyed Vireo
28-34
9-12
5
Warbling Vireo
33-35
13-14
3
Red-eyed Vireo
39-42
15-20
100+
Bank Swallow
32-34
10-13
50+
Barn Swallow
34-37
17-19
80+
House Wren
33
11
1
Eurasian Reed Warbler
30
9-13
60+
Gray-cheeked Thrush
50-54
26-37
30+
Bicknell's Thrush
46-50
24-30
12
Swainson's Thrush
48-52
25-36
100+
Brown Thrasher
62
67
1
Golden-winged Warbler
29
8
1
Orange-crowned Warbler
29-32
8-10
4
Kentucky Warbler
34-35
12-15
2
Hooded Warbler
30-34
9-14
4
Magnolia Warbler
24-28
?
Blackpoll Warbler
33-36
10-22
200+
Black-throated Blue Warbler
26-28
?
Palm Warbler
26-34
9-12
5
Yellow-rumped Warbler (Myrtle)
31-34
10-15
100+
Prairie Warbler
26-29
7-10
7
Canada Warbler
34
10-12
?
Yellow-breasted Chat
40-42
22-25
4
Saltmarsh Sparrow
36-39
18-20
60+
Clay-colored Sparrow
30-31
9-12
7
Field Sparrow
30-32
12-13
6
Lark Sparrow
32-42
20-28
1
White-crowned Sparrow
44
31
1
White-throated Sparrow
45-50
23-31
100+
Savannah Sparrow (Ipswich)
38-44
21-30
100+
Eastern Towhee
50
40
1
Summer Tanager
39-40
26-27
2
Blue Grosbeak
37
26
1
Indigo Bunting
34-36
14-17
10
Painted Bunting
34
1
Dickcissel
38-44
22-32
3
Orchard Oriole
40-42
19-22
2

How to avoid tag aliasing

Aliasing can occur when multiple tags emit a signal at the same time. Sometimes these interacting signals can produce a pattern which match a different tag that is not actually present. This is due to the nature of how the unique tag ID is encoded in the signal. However, the parameters used to define these IDs are quite stringent, making aliasing only an issue in specific conditions.

Strategic tag deployment

To help mitigate aliasing, we recommend keeping numbers low at any given tagging site. This can be done by staggering deployments, either spatially or temporally. Most aliasing is caused by tags which have the same burst interval but a different Lotek ID. That means if you have more than one burst interval in your selection of tags, you can deploy more tags at any given site with a reduced risk of aliasing. However, do not deploy more than one tag with the same Lotek ID, even if they have different burst intervals!