Kleine jagers klem tussen vis en vos (Ingrid Tulp)
Motus wildlife tracking system (Sjoerd Duijns)
1. Sjoerd Duijns, Alexandra Anderson, Yves Aubry, Amanda Dey, Scott Flemming, Charles Francis,
Christian Friis, Cheri Gratto-Trevor, Diana Hamilton, Rebecca Holberton, Stephanie Koch, Ann
McKellar, David Mizrahi, Christy Morrissey, Sarah Neima, David Newstead, Larry Niles, Erica Nol,
Julie Paquet, Jennie Rausch, Lindsay Tudor, Yves Turcotte & Paul Smith
Motus wildlife tracking system:
tracking op continentale schaal
4. SensorGnome:
Hoe werkt het?
• “geprogrammeerde” VHF zenders
• Database:
• Frequency offsets
• Burst interval (piepjes per
tijdseenheid)
• Continue ‘luisteren’ naar tags
• Zoekt in database naar een match
• Wanneer mogelijk, vebinding met
internet voor een live feed van de
data
5. Zenders
• 150.100 MHz (Europa)
• ~0.2 g tot ~2.6 g
• levensduur van 20 dagen tot 928 dagen
(afhankelijk van grootte en interval)
6. • CTT Life Tags
• Ontwikkeld door Cornell University
• Zonnepaneel, geen batterij
• ~4 billion unieke codes
• Vanaf 0.45g
• Werken nog niet ‘s nachts
• GPS-VHF Beacons
• VHF Beacons Kunnen data opslaan (temperatuur, activiteit)
• Data kunnen opgepikt worden zodra ze in de buurt van een
toren zijn
Nieuwe ontwikkelingen
7. Motus in aantallen
• ~ 900 stations verspreid over 28 landen (9-
76°latitude)
• 285 projecten met ~ 700 partners
• ~ 22,000 individuen gezenderd
• >200 soorten (vogels, vleermuizen,
insecten)
• ~ 700 million detecties
• 80+ publicaties
• ~ $100 miljoen CAD
9. Waarom gebruiken we
motus voor steltloper
onderzoek?
• Stopover en individuele
verblijftijd
• Timing van vertrek en
aankomst
• Bewegingen langs de kust
• Migratie afstanden
• Migratie snelheden
• Migratie routes
• Overleving
• In kaart brengen van
migratie Netwerken
13. • Grote variatie in timing en routes
Heeft het te maken met conditie?
Voedsel in DB staat onder druk
• Hogere kans op overleving (Baker et al. 2004. Proc R Soc B)
• Verhoogde mate van wind selectiviteit (Åkesson & Hedenström 2000. Behav Ecol Sociobiol)
• Snellere migratie over korte afstanden (Sjöberg et al. 2015. Anim Behav)
Negatieve populatie ontwikkeling
25. Migratie van insecten
Knight et al. 2019. Biology Letters
• Snellere migratie bij
toenemende
temperatuur en
rugwind
• Monarch 143 km op
1 dag (31 km/uur)
• Keizerlibel 122 km
op 1 dag (max 77
km/uur)
32. • Zender een deel van de populatie buiten je telgebied
(bv broedgebied), en meet het % dat door je gebied
komt
• Meet de verblijfsduur voor je sample
Aantal vogeldagen
= Aantal vogels
Gemiddelde dagen per vogel
Gemiddelde telling * duur = Aantal vogeldagen
Aantal vogels
% in telgebied
= Populatie schatting
De oplossing
Here are two years of data, which have been pooled together to calculate survival of migrating knots and for the first time we were able to prove that a knots survival, the chance of it returning after a successful breeding season, was determined by their body condition when leaving Delaware Bay. You’ll notice however that our coverage stops largely stops on the eastern seaboard. Therefore we had to go to the end of the line, Terra del Fuego.
Length of stay is about 12 days on average for each species but length of stay can range from 1-40 days.
It is quite variable but depends on mass of the bird at the time it is captured
The pink line is from the 15 red knots added in.
As birds get heavier, length of stay decreases. A 10% change in body mass per species results in an equivalent change in length of stay for each species
Migration speed faster in spring than in fall, largely because of an increase stopover duration in fall.
Migration speed faster in spring than in fall, largely because of an increase stopover duration in fall.
Migration speed faster in spring than in fall, largely because of an increase stopover duration in fall.
Surveys count what is present, and for animals that are on the move, this obvious fact leads to a variety of problematic biases. Many of these could be addressed by using tracking data to augment survey data.
Surveys of migrant birds are often “efficient” because large numbers of birds concentrate (in space and time) at a restricted set of stopover locations. However, because they are moving through an area, their behaviour can influence whether or not they are present at the time of the survey. This can lead to two important sources of bias – length of stay bias and frame bias.
Length of stay bias refers to the fact that length of stay at a location is directly related to the count. If the length of stay drops by half, the mean count will drop by half. This issue has been highlighted for shorebirds – rebounding populations of birds of prey could be reducing length of stay and leading in part to the observed declines in counts.
Length of stay bias refers to the fact that length of stay at a location is directly related to the count. If the length of stay drops by half, the mean count will drop by half. This issue has been highlighted for shorebirds – rebounding populations of birds of prey could be reducing length of stay and leading in part to the observed declines in counts.
Length of stay bias refers to the fact that length of stay at a location is directly related to the count. If the length of stay drops by half, the mean count will drop by half. This issue has been highlighted for shorebirds – rebounding populations of birds of prey could be reducing length of stay and leading in part to the observed declines in counts.
Frame Bias refers to the fact that birds can move in and out of the set of surveyed sites. We often don’t know what fraction of the population is counted in each region, which birds are counted more than once, what fraction of the population never enters the sampling frame, and whether this fraction changes over time. These issues can lead to important biases, whereby regional trends are difficult to combine and it’s difficult to say with certainty that observed declines are real – might birds simply have moved out of the surveyed areas?
The solution – is to tag a statistically rigorous sample of birds from the population and use tracking data from this sample to determine the time that birds remain in surveyed areas, and the fraction of the population the population passing through this sampling frame.
With tracking data we can convert potentially biased “survey counts” to unbiased “population estimates”.