As of today (27th September 2024), the situation remains largely as outlined in the previous blog. Approximately one-third of the tagged lapwings (6) have moved to France, where unfortunately another death occurred (Etoša, 5th September 2024). The rest are still staying in ever-growing flocks in eastern Bohemia, not far from the location where they were tagged (Picture 1). However, their departure is eagerly anticipated any day now.
Picture 1: A flock of lapwings preparing for migration, Photo: Miroslav E. Šálek
Although every child knows that "birds fly away to warmer lands for the winter," the variability with which different bird species approach this challenging task makes bird migration one of the most fascinating and diverse phenomena to study in the avian world. The question isn’t simply whether a bird migrates for the winter or not. Species, populations, and even individuals differ significantly in terms of where (how far), when (in the season and time of day), how (height, speed, or the number of "stages"), and along which route they fly. All these aspects can have profound impacts on the survival of individuals and the success of entire populations. And tracking birds using modern telemetry equipment allows us to gain revolutionary insights into the journeying birdsw’ behaviour. So today, we’ll focus on our six travellers and attempt to map out in detail what their journey to France can tell us about lapwing migration habits, thanks to the transmitters they carry.
Regarding the six lapwings currently in France, they have moved 740 to 1,150 km from their last location in eastern Bohemia. Although they have stayed at their French sites for a while now (since at least 19th July 2024), it’s still unclear whether they’ve reached their final wintering grounds or if we are observing them during a long migratory stopover. Looking at the wintering grounds of our lapwings, as established through decades of bird ringing (Cepák, J., et al. 2008: Atlas of Bird Migration in the Czech Republic and Slovakia), both possibilities seem plausible.
Naturally, none of the lapwings covered this distance in a single, direct flight. Each female broke the journey into 4–16 flights, taken over 5–14 days. It’s worth noting here that we considered a flight to be a movement of at least 10 kilometres without interruption. The total distance flown ranged from 930 to 1,850 km, which on average is 1.3 times the straight-line distance between their eastern Bohemian location and their current French site. However, the record holder was Jezinka, who flew more than double that distance (see Map 1), and her specific journey deserves a closer look.
Jezinka clearly hesitated for a long time before definitively leaving the Czech Republic. On 5th July, she set off and crossed the border into Germany (Point 1 on Map 1). The next day, however, she changed her mind and returned to the Czech Republic, not back to eastern Bohemia, but instead heading south to the Pohořelice ponds in southern Moravia (Point 2). After spending over a week there, she again headed west. She crossed the Czech border into Germany once more (Point 3), but apparently, she didn’t like it there either. While still flying, she turned back towards Bohemia, where she spent her last two days near Kladruby in the Pilsen region (Point 4), before finally deciding to cross the German border for good. Really not being a fan of Germany, she made an impressive flight of almost 500 km, crossing nearly the entire country, and landed just 400 metres from the Luxembourg border. The very next day, she arrived at her final destination in northern France.
Map 1: Jezinka’s hesitation.
An important aspect of migratory behaviour is the time of day when migration occurs. The vast majority of the distance was flown at night. Specifically, 37 out of 47 recorded flights (78%) took place at night. These night flights were generally much longer (with a median of 167 km compared to 28 km during the day), and thus, over 94% of the total distance was covered at night. Overall, we can say that lapwings migrate at night, although daytime flights can also cover significant distances, up to around 100 km. Although speculative at this stage, daytime flights may serve to find a better location for a migratory stop if the bird didn’t choose an ideal spot upon arriving at night.
Lapwings usually start their migration about an hour after sunset, typically shortly after the end of civil twilight (this is the time when the sun is less than 6° below the horizon, and you can still, for example, read a newspaper without additional light outdoors). The flight lasts on average four hours (sometimes up to seven) and the lapwing covers more than 200 kilometres on average. However, we’ve also recorded much shorter flights (just a few dozen kilometres) and, as mentioned earlier, nearly 500 km in one flight. Typically, the bird covers the entire distance in one stretch during the night. In five cases, we observed a second, much shorter flight after a pause.
The telemetry data has also revealed other intriguing details. The average travel speed of a migrating lapwing is around 50 km/h, although in some cases, speeds of up to 90 km/h have been recorded! The altitude at which they fly varies widely, ranging from a few dozen metres to over two kilometres. Generally, during daytime flights, lapwings tend to fly low, and the higher altitudes are reserved for long night flights. During these night flights, the lapwing ascends quickly in the initial phase and then gradually descends. Both these characteristics likely depend on weather conditions, which will require more detailed analysis.
Unfortunately, we can’t always take full advantage of the accuracy and frequent recording intervals that the transmitters offer during the day. Even if a lapwing starts its flight with a fully charged transmitter, the lack of sunlight at night causes the battery to drain quickly, which reduces the frequency of GPS position recordings after a while. As a result, we often only know large portions of the flight routes roughly, which is certainly a shame. This makes it difficult to assess what factors influence the lapwings’ choice of specific routes. Nevertheless, we’ve managed to record a few interesting observations. For instance, on Map 2, we can see how Nerea, flying at an altitude of just 200 metres, decided to take a look at the lights of night-time Leipzig (Map 2).
Map 2: Nerea’s trip over the Leipzig at night.
To conclude, although this analysis is based on the migration of a relatively small number of individuals, the patterns described above can, with some caution, be considered typical or characteristic features of lapwing migration. We also eagerly await to see what the transmitters will reveal once the rest of the tracked females begin their migration. Will this "second wave" of migration follow the same patterns, or will it differ in some aspects? For example, how will the size of the flocks that lapwings are now gathering into affect their migration? Although we unfortunately don’t know how large the groups (if any) were during the first wave, it’s highly likely they weren’t large. At the beginning of summer, lapwings were either solitary or in small groups. And what will the spring migration back to the breeding grounds look like? We will certainly return to these questions in future posts.
That’s all for today. Let’s wish our crested friends a favourable tailwind, and see you next time!