Sommer Park Preserve, Hopewell, New Jersey

Nature's Own Experiment
Hannah Suthers

The research preserve, Sommer Park, is a 108 acre former farm dating back to William Park in 1764 and discontinued as a working dairy farm in the 1960s. Since 1976 I have been monitoring the vegetative succession in the fields and wood lots and the resulting changes in bird life. At one point in time 38 years ago, when I started, there were fields ranging in age from an active pasture, 10 years from mowing, 5 fields at 20 years, a pasture at 40, a wet woods at 60, the border of Highfields at 75, and a climax woods at 95 years from logging. Birds occupied the habitats that met their needs.

Now 71% of the study area is wooded except two fields kept at the woody shrubland stage. Birds have reacted accordingly. Some grassland (E. Meadowlark) and shrubland (Willow Flycatcher, Chestnut-sided Warbler, Yellow-breasted Chat) species dropped out altogether. Closed-canopy loving Neotropical migrants, Red-tailed and Cooper's Hawks moved in. 63 species of birds breed in the study area.

Then came the freak storm of 29 Oct 2011 with some 3 inches of wet snow that bowed and snapped tops of trees still leafed out. Hurricane Sandy followed on 29 Oct 2012. 167 tree falls of cedars and hardwoods left gaps in the canopies. Nesting Scarlet Tanagers (numbers before snow-before Sandy-now 8-9-6), Red-eyed Vireos (17-11-12) diminished. Crested Flycatchers (10-7-3), and Red-bellied Woodpeckers (26-17-17) lost nesting trees. Common Yellowthroats (27-21-25) came in. White-eyed Vireos (0-0-4), Yellow-breasted Chat (0-0-1) and the Brown Thrasher (0-0-1) absent for a few years, returned. Blue-gray Gnatcatchers (3-5-9) and Black-and-White Warblers (0-1-6) increased in number.

Holding steady:

Catbird (55-47-57) shrubland
Wood Thrush (22-22-23) open forest floor
Ovenbird (25-30-26) forest ground nester

Declining:

Veery (15-9-8) forest interior
Am. Robin (40-46-21) forest edge
Blue Jay (24-14-16) forest interior and edge
Blue-winged Warbler (12-7-6) early shrubland
Yellow Warbler (6-4-2) forest edge, shrubs
Rose-breasted Grosbeak (13-12-6) forest interior and edge
Common Grackle (12-11-4) edge, evergreens
Baltimore Oriole (13-8-7) forest edge
Brown-headed Cowbird (11-9-7) edges
House Finch (4-5-1) evergreen shrubs

It will be interesting to follow the breeding bird population as the gaps in the woods fill again with vegetation (hoping that deer don't eat the emerging seedlings).