Q. What kinds of birds are passing through the New Jersey Highlands?
Ted Stiles: In the fall, the birds that were just hatched this year -- as well as many of the adults -- many of them are migrating south and they use the Highlands migration corridor. They need it for feeding and resting in between their migratory flights. And so the Highlands are a critical food source and refuge for these moving species.

Q. Does the Highlands see a variety of bird species?
Ted Stiles: The Highlands serves all of the migratory land birds that are moving from the boreal forests through New Jersey to points south. It also serves the resident species here and moving from south. And ultimately many of the boreal forest birds will come south from their breeding habitats in Canada and will be wintering in the Highlands as well.

Q. What do the forests of the Highlands offer?
Ted Stiles: Forests provide a habitat with both food and shelter for different types of species, species that have adaptations that allow them to survive in those areas. You can predict where you can find certain species that use old growth or closed canopy forests, whereas you have successional areas that provide habitat for other species. The critical need for many of these species is dependent on the abundance of different types of habitats, and in the Highlands we have some large sections of relatively closed canopy forests which provide an unusual resource for birds that are in decline in many parts of eastern United States. So it's very important to retain these forests that have these closed canopy areas.

Q. Would the Highlands then have a global connection, in terms of bird migration?
Ted Stiles: The global importance is that many of the birds and other things too, like mammals, and bats -- bats for example have two places of residence and then a lot of intervening stops in between those residences, they have a northern and southern home. So the global significance is that many of these breeding areas and wintering areas serve as necessary food stock places and resting places for birds that are going to Costa Rica, and going to Mexico, or to the Caribbean, or to Venezuela for the wintertime. On the other hand, they're serving as wintering spots for birds that are going to Newfoundland, or Nova Scotia for the summer. So, they serve very much in the global context.

Q. Do bird populations play a role in the health of the habitat?
Ted Stiles: One of the things that I study are the relationships between birds and plants. Many of the species in the Highlands are frugivorous -- they eat fruit. And in doing so, they disseminate seeds which are important for the regeneration of many of the plants in the Highlands. If bird populations decline, many of the plant species that are disseminated by those birds would be impacted. It would be hard to determine how badly they would be impacted, but it could change the nature of the forests through the Highlands.

Q. Why the variety of habitats?
Ted Stiles: The nature of the plant and animal communities that have evolved and are successful in different habitats are specific to those environmental characteristics, so that's what you have in the Highlands. You've got a specific set of environmental characteristics which support a specific group of plants and animals. The Highlands provide the space and sylvan types of environments for different species to survive. And within that, the context is that all those species are incorporated, they are the biodiversity. With that in mind, the Highlands is very important in providing space for that component of the biodiversity to exist.

Q. Describe forest fragmentation.
Ted Stiles: The forest creates a habitat that has shade. The forest has a relatively continuous coverage of trees, and fragmentation is the cutting up of that continuous coverage in some way. It's the opening up of the canopy in some places that allows both light penetration as well as encouraging adjacent habitats that are not so high and not shady. These are the “edge” habitats, the habitats that lie at the edges of the fragments. These edge forests provide habitat for different species, and some of those species in penetrating the forests provide a problem for the species that live in the forest.

One example: a brown-headed cowbird parasitizes other birds’ nests; it actually lays its eggs in other birds’ nests and causes a problem for some of the interior species in the Highlands. In addition, you have penetration by predators that are not necessarily forest predators, but are often predators from areas of development -- things like cats and dogs that can come into forests from edge habitats.

You also have light penetration. In the northern hemisphere light is coming from the south. When the light penetrates, plant species that normally cannot live under shade in the forests are able to be successful, so you have different species of plants that penetrate the forest -- which changes the habitat. That change in habitat affects the animals that live there and so both the plant community changes because of fragmentation, as well as the animals that penetrate the forests from the edge, which are different species, and they provide problems for those species that are specifically adapted to understory conditions. Because those understory conditions get changed, it impacts these species and they cannot reproduce as successfully, and then populations decline.

Q. Fragmentation changes the long-term health of the forest?
Ted Stiles: Fragmentation occurs at all levels. It happens naturally because trees fall in the forest and create gaps, which is the natural process of forest replacement. Where a tree falls, that will be replaced by another young tree. However when it happens at more intense situations, situations where you have development, or you have a power line cut, or where you have any sort of significant change in the canopy conditions where you allow the entry of both light and the other species that are characteristic of lower forest areas, then that fallen tree might not be replaced.

Q. What’s the key to the water supply of the Highlands?
Ted Stiles: The water supply is incredibly valuable. We need water, all of us, and so do the plants and animals that survive in the Highlands. New Jersey is blessed with having quite a bit of water. We have quite a bit of rainfall, and the question is how fast does it go back to the ocean, how fast does it runoff? Is it available for us? If you have forest cover, the leaves that fall create a humus layer and the humus layer acts like a sponge, and it also acts like a filter, so that the water is soaked up by the humus layer instead of running immediately into the streams and rivers and flooding downstream. Rainfall soaks into the humus layer and then goes into the groundwater, it gets filtered into the ground water, and so it is cleaned, and it provides a source which is very slowly released to the streams and ultimately to the reservoirs for drinking water. That humus layer also reduces flooding and provides water for the diversity of plants and animals that live there. So the forests of the Highlands and the humus layer that is created by the falling leaves creates this water availability which sort of spreads out our rainfall over a longer period of time and makes it available.

Q. So it’s not the geography – it’s the forests?
Ted Stiles: The forests of the Highlands drop leaves which create this humus layer, and the humus layer can be as deep as forty to forty-five inches in some places and serves as a tremendous sponge which soaks up the water, reduces the speed of the runoff, slowly releases it to the streams as it also filters it going into the groundwater. It's an incredible resource for the plants and animals that live there as well as it provides clean drinking water for the people that surround the Highlands and the huge population centers.

Q. How have these forests survived?
Ted Stiles: When Europeans arrived here -- we don’t have a good historical record -- but there was basically extensive canopy cover in the Highlands that was probably broken in some places by disturbance, but really it was probably mostly forest. Europeans were agriculturists. They got here and wood was needed in England and other places in Europe, so they cut the trees down for agriculture and moved them back to Europe, took the wood back to Europe and used it here as well. The maximum deforestation, occurred probably in the 1850s, 1860s, when basically most of the forests were removed at least one time. Where there were poorer soils, the forests were removed and then the land was left. On the lands with richer soils, the forests were removed and people continued using the land as agricultural areas. With agriculture moving to the Midwest and other parts of the world, many of these forests are returning to the Highlands as second growth. Many of them are as much as two hundred years old and more, having been cut only once. But they are returning now, so there's been quite a history of disturbance up to now in terms of primarily agriculture use.

Q. How have the forests fared in the modern era?
Ted Stiles: The general trend taking place in the Highlands is that with the increase in population, there's been a change from an agricultural landscape to one where you get into more successional forests, and then the return of the forests has been fragmented by the movement of people and houses and businesses into those areas. It’s a transition from open agricultural land that was going back to forests, and now it's going into fragmented areas with people living in them. So, that's the major trend that's taking place in the Highlands.

Q. Is the Highlands nationally significant?
Ted Stiles: I think that the Highlands are definitely a nationally significant area, and it comes from a couple of rationales. One is that the Highlands is a large, relatively contiguous area, an area that can have natural areas that are contiguous with one another over a pretty good distance. I think even more importantly than that, it has to do with the proximity with the large populations of the megalopolis of the northeast. We have here a resource that is available for people to enjoy and understand things about their natural heritage that otherwise they might not have the opportunity to do.

I'm a biologist, and I think that preserving the plants and animals that are native to this area is a very important element, a reason by itself for preserving the Highlands. Those plants and animals have a right to live there. However there are many reasons that, all combined, meet many people's interests and goals and needs -- everything from the tremendous amounts of water used by people, to the recreation, to the continuation of a rural agricultural style of life, to the importance of the biodiversity that is there which may provide useful resources for people in the future. There are thousands of different chemicals in plants in the Highlands that are yet undetermined as to their potential value for people. There are so many different things that are of value that we can’t let it go.

Q. Any guess on what the Highlands might look like in the future?
Ted Stiles: New Jersey has recognized the importance of its remaining open space, and the people of the state have been very diligent since the sixties in providing tax dollars to be able to try to preserve our natural heritage. It's been pretty successful and needs to be more successful. And so, I'm very optimistic about the future of the Highlands. I think -- that with the resources that New Jerseyans have committed to preserving our natural areas over the past forty years -- that they will continue to do so, and they recognize that the value of our natural heritage is something they can in fact protect. I believe that they will continue to do so and that we will see a good part of the Highlands preserved and protected for them.