Hula Lake is Aflutter with Migrating Birds and Butterflies

Birds don’t feel the cold, butterflies are cold-blooded like reptiles, and other fascinating facts: A conversation with Inbar Rubin, Field and Training Director at Hula Lake Park, on the winged migrants coloring Israel’s skies.
As a child, you probably learned that birds migrate to warmer climes in order to avoid the cold, but according to Inbar Rubin, Field and Training Director at Agamon Hula Lake, this is only partially true: "Birds don't get cold. They have feathers, which is the best body insulation that exists. It's as if they're always covered by a down blanket. For this reason, weather is not the main reason for migration, but rather food and how it's affected by the weather. In cold countries, during the winter months most of the birds’ regular food sources are covered by snow, and it's almost impossible to access it. In addition, the daylight hours of winter are meager, and the birds simply don't have enough time to look for food. This is why they migrate to warmer countries where there is no snow and rather more hours of daylight."
Most birds migrate at the end of the winter from Africa and Asia to Europe, and they arrive in the summer. Awaiting them there are long, light-filled days and abundant food sources - seeds, plants, reptiles and rodents – that appear at winter’s end in order to proliferate in time for the next winter.  

Western tiger swallowtail, Hula Lake Botanical Garden. Photo: Inbar Rubin, KKL-JNF
Half a Billion Birds
Hula Lake Park (commonly known as ‘Agamon Hula') is located on one of the two most significant migration routes in the world – the Great Rift Valley, previously known as the Syrian-African Rift. Every migration season no less than 500 million birds fly over the lake. That is, half a billion!
In the course of their flight, some of the birds opt to stop at Hula Lake and the vicinity and to stay here rather than continuing on to their final destination. "There are a number of reasons for this," Rubin explains. "The lake is a very safe place for them in terms of predators, there is a lot of food in the adjacent agricultural areas, and the weather is ideal for the birds. Actually, ever since the Hula Lake restoration project, a habitat was created here that provides exactly what many species of birds need. This is something that is quite unique, even on a global level."
Intergenerational Migration
However, this is not only about birds. There are other creatures that migrate, including butterflies. "Their need for warmth is much more critical than that of the birds because they're insects and are not warm-blooded," Rubin says [fun fact – the fuzz you see on butterfly wings are not feathers at all, but rather scores of scale-like hairs]. "They are very sensitive to changes in climate, so if it's too cold or too hot, it affects them immediately. In addition, in order to survive they need two types of plants – nectar-producing plants for food and host plants on which to lay their eggs. Migration is also for coming to regions where plants like these can be found."
In contrast to birds, which leave a specific locale and return to it a year later, butterfly migration is "intergenerational". Due to their short lifespan, it is most probable that the same butterfly will not return to where it came from, but its descendants will. In the course of migration, the females lay eggs and continue on. When the eggs crack open, larva that will eventually become pupa and then butterflies will continue the same migration pattern as their parents did. "Butterflies have genetic knowledge, which is why they know that they have to migrate without having to follow their parents," Rubin explains. "If at the beginning of March I transformed from being a pupa to a butterfly in Saudi Arabia, then I'm living the good life because I have lots of food, but if I feel that food is slowly disappearing because everything is drying up, I need to continue to another destination. The knowledge of where to go and how to get there is dependent on the butterfly's genetic knowledge."
African monarch, Hula Lake Botanical Garden. Photo: Inbar Rubin, KKL-JNF
African monarch, Hula Lake Botanical Garden. Photo: Inbar Rubin, KKL-JNF
A Butterfly Paradise
Back to Hula Lake Park. As part of the regional restoration project, KKL-JNF created a botanical garden here where only plants that formerly grew in the valley or the swamp are grown. Over the years, it was observed that the flora also affects fauna that find their way into the garden, including butterflies. "The botanical garden is a protected refuge for plants in danger of extinction," Rubin said. "These plants are crucial for butterflies – both host plants for laying eggs and nectar-producing plants for food. In addition, the aquatic plants planted here behave in the exact opposite to regular plants – they begin to blossom in the spring and flower in the summer, even when it's hot. The butterflies used to rely on the water plants in the past and we reintroduced them. Today there are no less than fifty main species of butterflies at the lake and its environs."
Two of these species are the Painted lady (Vanessa cardui) and the African monarch (Danaus chrysippus) - species of migrating butterflies that come to the lake. For them, the botanical garden is nothing less than paradise. "The host plant of the African monarch is considered detrimental for agriculture," Rubin explains. "It is poisonous, but its poison protects the monarch's eggs as well as the butterfly after it's born. Farmers usually destroy this plant, but we enable it to live and grow at the lake, and since then we have become the northernmost point that these butterflies migrate to."

Inbar Rubin hopes that more and more butterflies will come to this region and find it to be as natural and safe a place for them today as it was in the past. "Butterflies are important for us first and foremost for ecological reasons. They pollinate plants and serve as food for other animals, and they are also part of a complex ecological fabric which, if it is damaged, could collapse entirely. And there are also our personal reasons – butterflies make us happy; they make our hearts expand, and besides all that – they really do give us a [thrilling] sense of "butterflies in the stomach".