Schooling days: birdwatching swallows before they leave Japan

 

Swallows are birds living near us. They build their nest under the eaves of our home, the walls under the roof, things like that. In late spring they come to Japan, decide where to raise their chix, mate, hatch the eggs, feed their kids, … then? If lucky, the chix should grow big enough to leave such a small estate of their nest (; my post on July 5, 2019). Come to think of it, we see their childcare days, but not afterward. What will they do? Returning straight to southern places, like Taiwan, ASEAN countries …? Can the teenager swallows take such a long-distance flight without learning how to feed themselves and gaining enough strength for a long haul? Unlikely. What then do they do before they leave Japan?

Busy holding eggs

According to the people for Wild Bird Society of Japan (WBSJ), swallows love to rear their chix in human settlement because of security reasons. Having their eggs near us could prevent onslaught by predators like snakes, mammals, etc., as we positively expel their approach. When the chix become big enough to leave their nest, young swallows fly around to learn feeding themselves first. Schooling days will last for about 3 to 4 months. When they think they have eaten sufficiently to maintain their stamina for returning to southern countries, they individually decide their departure. i.e. They do not build a flock like swans for migration. However, during their preparation days, they behave like a member of a group. Moreover, they do so only from dusk to dawn. They sleep in a particular place en masse. At sunrise and sunset, lots of lots of swallows congregate in a special place. In Japanese, such behavior is called “Bedtime for swallows つばめのねぐら入り.”

In any case, their tales are cute.

During the prep days for a long trip, swallows commute between such bedroom and their hunting sites daily. At dawn they leave home, hunt and eat during day time, then return to bed at dusk. Their bed is the top tips of reed leaves. The birds are so light that they can stabilize their body on such a delicate structure. Also, they do not use a pond with a handful of reeds. They sleep in a group to achieve a certain level of security by the power of numbers. So, they need a large field of reeds for Bedtime. i.e., If we plan birdwatching for Bedtime for swallows, we must go to a riverside with a sufficient colony of reeds.

It’s a scenery of Sagami River 相模川
where its downstream begins more or less.
Sure it has a bit of reeds on its bank,
but we don’t think it is “substantial.”
So do swallows. No hostels for them here.

WBSJ is yearly updating an introductory map for us to witness “Bedtime.” Some sites, like Watarase Yusuichi 渡良瀬遊水地 listed in the Ramsar list, the field of reed is large. For Watarase, they have 33 km2 of reeds and can accommodate constantly 30000-60000 swallows to sleep. Er, well, having said that, we do not have to plan a holiday travel for swallows, if we do not require the size of numbers for swallows. There are several spots in metropolitan Tokyo area where swallows sleep during summer. For example, Flood-ControlPark for Sakai River of Kanagawa Prefecture 神奈川県立境川遊水地公園 (; my post on January 28, 2022) has a size of field of reeds capable for being beds of 300-500 swallows. We can watch them come to sleep from late July to early August. A bit larger swallow hostel with good access (for humans) is near Haneda Airport. Yup. That International airport for Tokyo. It is in the estuary of Tama River 多摩川.

A beautiful sunset in Tama River, Tokyo

Every year, WBSJ holds a couple of “Bedtime” watching events near the airport. It’s a uber popular dusk and difficult to secure the seat, allocated through lottery. But, ta-da! This year, Naomi hit a Jack-pot, and had a chance to join the occasion! This week and the next, I tell you my adventure with swallows near Haneda, on the bank of Tama River. Due to hydrological reasons the fields of reeds normally appear on the Tokyo side of the bank, but it is easier observable from Kanagawa. So, in this adventure, I keep my foot in our home prefecture. 😉 The size of the field is definitely larger than that for Sakai River. The reeds along Tama River can host 3000-5000 swallows regularly. Oh, one caveat. Swallows and reeds do not stay in the same spot every year. People for WBSJ told us for 2024 they moved a bit upstream, away from Tokyo Bay. So, my report for this year may not exactly apply for the next year. Next week, I tell you where I’ve been. It was in 5 minutes’ walk from several stylish tower blocks. Lots of residents did their evening jog along the river. 😊

I think it’s a good place to sleep,
not only for swallows but also for humans.

Wild Bird Society of Japan

https://www.wbsj.org/