March 25th marked the end of the spring migration season, as Sněhurka, the last hesitant lapwing, arrived near her previous year's nesting site. According to transmitter data, Lulu had already taken advantage of the early spring sun and began incubating her eggs around March 17th. She was soon joined by Kikina and, more recently, likely by Gracie. Around March 25th, Turbo—the only male lapwing in our study to transmit data, albeit sporadically—returned to his last year's capture location. The season of long journeys is over, and the equally thrilling nesting season begins.
Unfortunately, we won’t be able to track all our tagged birds throughout this period. Prskavka’s journey back ended fatally—most likely taken by a bird of prey, based on the timing and post-mortem movement data—in eastern France. Jezinka’s transmitter stopped working shortly after her return home, for reasons unknown. As of now, only 9 of the 20 tagged lapwings remain active. Soon, however, we'll begin trapping a fresh batch of our feathered companions, and if we’re successful, we’ll start introducing them to you one by one. There’s certainly much to look forward to!
Picture 1: A flock of lapwings in flight.
The journey home
Today’s blog topic is obvious: we’ll explore the return journey of ten lapwings we were able to track from their departure to their arrival back home. Using their stories, we’ll examine the patterns of spring migration and compare them to the autumn journeys we’ve discussed in previous blog posts (Migratory patterns, Migration and wintering grounds). Despite only ten birds returning, we were lucky to gather a well-balanced dataset from both main wintering areas used by Czech lapwings—five spent the winter in France, and five on the Iberian Peninsula. This not only allows us to describe their journeys but also to compare these two groups. Of course, with such a small dataset, any conclusions should be taken with caution. Still, the data provides some intriguing insights and sets the stage for future questions and analyses as our dataset grows.
To “stuff” all the lapwings’ movements into tables, we analysed their position changes on a daily and nightly basis. If a lapwing moved at least 20 km between the first and last GPS position within a given day or night, we counted it as a migratory move. Migration was considered complete once the bird came within 20 kilometres of its previous capture location. Thankfully, all ten tracked lapwings returned either directly to their previous nesting site or to its immediate vicinity—making our job a lot easier!
Picture 2: Timeline of the spring migration of our Lapwings.
By day or by night?
Compared to the drawn-out autumn migration (from late June to early December), the spring return was much more of a sprint. Amálka was the first to set off on February 14th, and Sněhurka was the last to arrive on March 25th. On average, the lapwings spent 20 days migrating, though there was wide variation. Lulu, for instance, covered her 1,300 km journey in just a week, while Oliva took a full month to fly 2,370 km. Unsurprisingly, only a portion of migration days and nights were spent flying—the rest were used for rest and recovery.
We recorded 48 nocturnal and 39 daytime migration events, suggesting a roughly 40% chance a lapwing wouldn’t stay in the same place for more than 24 hours. Daytime flights covered an average of 75 km (ranging from 20 to 173 km), while nighttime flights averaged 319 km (27–1,026 km). Nerea’s 1,300 km flight on November 11th last year still holds the record. As in autumn, lapwings mostly migrated at night. However, daytime flights were more frequent in spring (45% vs. 22% in autumn) and longer (median 52 km vs. 25 km), making up 16% of the total spring migration distance compared to only 5% in autumn. This suggests that daytime migration plays a somewhat larger role in spring.
Iberians vs. the French
Now for the promised comparison between our two lapwing groups, divided by wintering location. The birds that wintered on the Iberian Peninsula had to travel about twice as far (averaging 2,430 km) as those in France (1,212 km). Interestingly, both groups began their migrations on the same average date: February 21st. However, the Iberians took six days longer (23 days vs. 17) and had more days of actual flying (10 vs. 6), with the rest spent on stopovers.
When comparing total migration speed (distance divided by travel days), the Iberians averaged 106 km per day versus 87 km for the French birds. Both groups covered similar distances during daylight (299 km vs. 282 km), meaning the difference in total distance was achieved almost entirely at night. Notably, all Iberian lapwings only began flying during the day after they had reached France. Perhaps lapwings from more distant wintering grounds initially focus on catching up to their French counterparts and slow down only once the distance gap is closed, traveling more leisurely in mixed flocks. Every answer seems to raise new questions—classic research!
One obvious question is why some lapwings choose to winter much farther away, on the Iberian Peninsula, when France would suffice. While we can’t read their minds, mortality rates might offer a clue. The wide-open plains of France’s Champagne region claimed the lives of four of our birds (and saw transmitter failure in two more), while all lapwings wintering on the Iberian Peninsula survived without issue. Prskavka, too, was lost after making the mistake of stopping in Champagne on her way back. Whether this observation holds up will be clearer as we follow more birds in the coming seasons.
Do birds really not know borders?
To wrap up, here’s a mystery that popped up while following the full migratory cycle of our feathered friends. Birders often like to say that "birds don’t recognize borders," and it’s true—marked birds move freely across countries without regard for political boundaries. And yet...
Remember Jezinka’s strange detour last autumn (Migratory patterns)? She crossed into Germany twice, only to return to the Czech side each time, and did something similar on her way back this spring—settling in Germany for a few days before finally re-entering Czechia. Sněhurka did the same: flying in from Dresden, she turned back near Česká Lípa and spent two more days in Germany. Nerea, too, pulled off a double U-turn when attempting to fly from France to Germany.
These are just a few intriguing fragments that beg the question—do birds somehow sense borders? Could they be responding to subtle landscape cues shaped by different farming practices or land ownership? But how would that work at night, when most of these maneuvers occurred? Could streetlight density play a role? Do these changes mark a “step into the unknown”? And how detectable are such transitions anyway? Who knows. But these curious border dances are worth watching—not just in lapwings, but perhaps in other migratory species too.
That’s all for today. Next time, we’ll dive into one of the many promising stories from this year’s nesting season!
Picture 3: The journey back to the Czech Republic of Jezinka, Sněhurka and Nerea.