BIRDS IN AGRICULTURAL LANDSCAPES

Three tanks of  gas is my self-imposed limit- that point at which my shoulders and mind are tired enough to make continuing on less safe for something as strenuous as chain-sawing.  On this day, however, the third tank and four more hours of labor had gotten me to where I needed to be- at the completion of beating back decades of landscape neglect.  A profusion of multiflora rose, autumn olive, privet, burning bush, Japanese barberry, bittersweet, amelopsis and other non-native invasives had overrun the borders of the ten-acre Connecticut farm now operated by Bird Conservation Research, Inc. as a field station.

To be sure, such border creep into agricultural land is largely the consequence of seed planting by native birds that disperse the fruits and seeds of exotic plants.  However, such creep is not compatible with the goals of production agriculture, and our mission for the past four years has been to maximize wildlife values of landscapes within the constraints of an effectively run agricultural operation.  Such borders, although wildlife-planted, are far from having the optimal vegetation composition for these locations.

Now that these borders are cut back (although the gargantuan task of turning the resulting slash into wildlife brush piles remains ahead), we are examining available options for replanting the borders with superior vegetation.  The borders will shrink from their present 30-75 foot-wide swaths to a more modest but agriculturally practical 15 foot edge that is punctuated by mature trees.  The understory is to be converted from invasive exotics to high wildlife value natives, like our various species of evergreens, hollies, viburnums, dogwoods, shadbushes, cherries, roses and aronias, as well as to non-invasive cultivated plants that are also favored by wildlife.

It is important to recognize that wildlife values are not confined to those species that breed on the property, but also include those conferred by species that pass through the area- notably migratory birds.  Hence, plantings must have value at all seasons.  Species that flower early and late, species that have persistent overwintering fruit and species that offer substantial cover, roost sites and nest sites are the types of plants to be selected.

At present, the field station is home to species that successfully use agricultural landscapes like the American Woodcock (we are presently working on banding our local population).  It also serves as a migratory stopover (and possibly incipient nesting population) to such typically Midwestern species as the Vesper Sparrow (territorial males in early spring), Savannah Sparrow and Clay-colored Sparrow (present spring and fall).

American Woodcocks nest and hatch young well before the haying season and often build nests in the edge adjacent to hayfields.

WHERE THE BUFFALO ROAM

The shortgrass prairie habitat of the American Bison is featured in this video.

In its tour through AP Environmental Science topics, the next installment of the Living World video series focuses on three additional biomes.  It begins by examining temperate grasslands, and explores the physical environmental factors that favor the development of grassland environments- continental climate, limited rainfall and wildfires.  It also explores the relationship between perennial grassland vegetation and the animal species it supports, notably the American Bison, Pronghorn Antelope and Black-tailed Prairie Dog.

The focus then shifts to rainforest environments, first temperate rainforests and then tropical.  It compares and contrasts these, illustrating the coniferous nature of the temperate systems and the vast diversity of broadleaf vegetation that fills tropical systems.  In both environments, abundant moisture produces trees of great size, although the longevity of temperate rainforest giants is unsurpassed.  The video concludes by depicting the bird life of both systems, highlighting in particular the specializations employed by the diverse avifaunas of tropical rainforest.

This video, like all in the series, is available through Arts and Academic Publishing, the publishing partner of Bird ConservationResearch, Inc.

THE REMAINS OF A CONNECTICUT GRASSLAND: A FORTY YEAR HISTORY

The switchgrass-sedge grassland of Great Meadow is now largely invaded by cattails and reeds.

The birds were actually better this time around.  In June of 1976, pickings at Great Meadows in Essex, Connecticut were a bit slim, with gulls being among the most abundant species present.  Aside from the ubiquitous Common Yellowthroats, Swamp Sparrows, Marsh Wrens and lone Bobwhite, there was not much of interest present.  In contrast, during this June of 2016, gulls were uncommon and Bobwhites had disappeared, but multiple Ospreys were nesting and several Purple Martins flew overhead.  Both were all but absent in earlier years.  Great Egrets, confined to the river mouth in the 1970s, were also now conspicuously present, as were Rough-winged Swallows, which had replaced formerly common Bank Swallows.  To round things out, a Spotted Sandpiper fed along the banks of the adjacent Connecticut River and a Common Tern explored the river and adjacent tidal creeks.

Forty years have now passed since my first investigation of this extensive lowland bordering the lower Connecticut River.  I had initially gone there to study the extended ecotone between the site’s weakly brackish marsh and adjacent upland.  I thought the wet, grassy meadow that developed there was about as close as southern New England could come to having an extensive natural grassland, and I wanted to document its nature so that I might determine its persistence over time.  Toward that end, I inventoried the entire site and also established a study plot to quantify the presence of key community members.  My plot, chosen to be representative of the site as a whole (although I noted that there was a gradient in species composition from the north to south end), demonstrated that the predominant species were switchgrass (Panicum virgatum), a short species of bulrush- Scirpus americanus, and a sedge- Eleocharis palustris.  In all, I found 11 herbaceous species occupying the 100 m² plot. 

In 1983, I re-visited the meadow and observed that the community was much as it had been seven years before.  However, during this 2016 survey, I found that the ecotone had changed dramatically, with cattails and reeds invading much of it.  Furthermore, S.  americanus now appeared to be present primarily along the edge of the Connecticut River.  This observation left me perplexed enough that I began to doubt my initial identification, but upon later examining specimens I had collected both in 1976 and 1983, I found that my initial determination had been correct.  In the place of this species, I found that the sedges S. fluviatilis, S. atrovirens and the forb Peltandra virginica had become widespread.  I had recorded these species on my 1976 surveys, but none had occurred in the study plot, indicating that they were less common than now.  Switchgrass, although still present, was also not nearly as common as it had once been.  Even into 1983, I was still describing the site as a Panicum meadow, but this characterization no longer held.  Moreover, the entire meadow itself had shrunk from about 6 ha in 1976 to about two ha at present.  All these changes suggested that the site had become wetter over time, with the new dominant species t.ypical of emergent marsh rather than upland ecotone.  Human manipulation in the form of expanded mowing further assisted with reducing the meadow’s extent and, indeed, portions of the meadow have in the past been mowed for hay.

So what is to be gleaned from such long-term observations?  Well, first of all, I’ve concluded that my initial characterization of the meadow as a wet, albeit upland grassland was a bit generous.  With the benefit of now having examined all of the major herbaceous wetlands of the lower Connecticut River for decades, I think that it is more reasonable to characterize such meadows as simply vegetation zones within larger marsh ecosystems.  Furthermore, it now is clear that such communities are not static entities, but are rather dynamic associations that change over time in response to changing physical and competitive environment as as well as to human manipulation.

Alas, the notion of naturally persistent grasslands in southern New England is for me one that has become progressively harder to believe in.  We might still hold out some hope for the reed-canary grass (Phalaris arundinacea) ecotones of more completely freshwater marshes further inland, as Phalaris appears to be aggressively competitive with other species.  However, here again, it seems more reasonable to characterize such habitats as simply marsh vegetation zones rather than upland systems.  I suppose dune grass communities of the coast, nominal though they are, hold the only real claim for being naturally persistent southern New England grasslands.