Research

Spatial population dynamics of a grassland bird as revealed by the North American Breeding Bird Survey. Code available  here .

Spatial population dynamics of a grassland bird as revealed by the North American Breeding Bird Survey. Code available here.

My current research interests include: 1. early detection, spread, and ecological consequences of biological invasions; 2. grassland bird ecology and conservation; 3. spatial synchrony of population dynamics; 4. conservation survey design and citizen science; and 5. waterbird ecology (riparian and tidal systems).

 

Biological Invasions

Biological invasions are costly and pose serious risks to human and ecological health.

An Acadian Flycatcher nesting in the fork of a Hemlock branch. An invasive insect, the Hemlock Woolly Adelgid, kills a preferred nesting tree and negatively alters forest structure for this species.

An Acadian Flycatcher nesting in the fork of a Hemlock branch. An invasive insect, the Hemlock Woolly Adelgid, kills a preferred nesting tree and negatively alters forest structure for this species.

How do we best deploy resources to provide early detection and response to forest pests? How do disturbances caused by these organisms affect forest birds? I am collaborating with other researchers in the Lockwood Lab at Rutgers University to investigate the former (optimal sampling design and protocols for terrestrial eDNA surveys). The latter formed the basis of my Master’s research, and I maintain an active collaboration with Dr. Terry Master and students to continue this. These studies have focused on the effects of a destructive invasive insect, the Hemlock Woolly Adelgid, on songbirds that inhabit threatened Hemlock-dominated riparian forests in Pennsylvania.

Allen, M. C., Sheehan Jr, J., Master, T. L., & Mulvihill, R. S. (2009). Responses of acadian flycatchers (Empidonax virescens) to hemlock woolly adelgid (Adelges tsugae) infestation in Appalachian riparian forests. The Auk, 126(3), 543-553.

Allen, M.C. & J. Sheehan. (2010). Eastern hemlock decline and its effect on Pennsylvania’s birds. Pages 232-245 in S. Majumdar, T. Master, et al. (eds.) Avian Ecology and Conservation: Pennsylvania Perspective with National Implications. Pennsylvania Academy of Science, Easton.

Barnes, K. B., Ernst, N., Allen, M., Master, T., & Lausch, R. (2018). Louisiana Waterthrush Density and Productivity in Hemlock-dominated Headwater Streams: The Influence of Stream Morphology. Northeastern Naturalist, 25(4), 587-598.

 

Grassland Bird Conservation

conversion of Natural grasslands to agriculture and intensification of management on these lands have created a conservation crisis.
 

Bobolink relative abundance on two fields at Duke Farms, NJ in summer 2018. Rotational ‘conservation grazing’ will be implemented on the left field in 2020 and population responses will be evaluated. For scale, these former farm fields of heiress Dorris Duke are ~1 km long.

Bobolink relative abundance on two fields at Duke Farms, NJ in summer 2018. Rotational ‘conservation grazing’ will be implemented on the left field in 2020 and population responses will be evaluated. For scale, these former farm fields of heiress Dorris Duke are ~1 km long.

I am currently investigating the drivers of grassland songbird populations in agro-ecosystems, and potential policy solutions to stem their declines. This has primarily involved using public data to build an integrated socio-environmental model of the interrelated effects of climate, farm management, commodity prices, and conservation spending. I’ve also led field experiments investigating ways to make anthropogenic grasslands, including hayfields and airports, more amenable to grassland bird reproduction. A recent collaboration with biologists at Duke Farms Foundation evaluates the potential for ‘conservation grazing’ in mimicking natural disturbance, reducing management costs, and providing a model for regional farmers. Baseline surveys for this project commenced in 2018 and will continue for four years (2 yrs pre-introduction and 2 yrs post).

Allen, M. A., et al. (in prep.) Shifting geographies of spatial synchrony in North American grassland birds: a window into regional population drivers and vulnerabilities. Target: Conservation Biology.

Allen, M. A., Lockwood, J. & Burger, J. (in prep.) Climate-driven variation in farmer management decisions explains population fluctuations in a grassland bird: an integrated socio-environmental model. Target: Journal of Applied Ecology.

Allen, M. A., Burger, J. & Lockwood, J. (accepted with minor revisions) Evaluation of unharvested refugia for grassland bird conservation within active hayfields. Avian Conservation and Ecology.

Allen, M. C., & Peters, K. A. (2012). Nest survival, phenology, and nest-site characteristics of Common Nighthawks in a New Jersey Pine Barrens grassland. The Wilson Journal of Ornithology, 124(1), 113-118.

Allen, M. C., Almendinger, T., Barreca, C., Van Clef, M., & Lockwood, J. (2018). Grassland bird ecology at a future conservation grazing site, Duke Farms: abundance, distribution, reproduction, and predator communities. Submitted to Duke Farms Foundation, New York, NY.

Tsipoura, N., Allen, M. C., Peters, K. A., & Mizrahi, DS (2014). Grassland Bird Productivity on Military Airfields in the Mid-Atlantic and Northeast Regions - Final Report (#11-408). Department of Defense Legacy Resource Management Program, Arlington, Virginia, USA.

Peters, K. A., Allen, M. C., & Tsipoura, N. (2012). Avian Response to Grassland Management Around Military Airfields in the Mid-Atlantic and Northeast - Final Report (#10-381). Department of Defense Legacy Resource Management Program, Arlington, Virginia, USA.

 

Spatial Synchrony in Population Dynamics

The degree of synchrony among populations in a landscape can influence the chance of extinction

Spatial synchrony in Grasshopper Sparrow populations based on Breeding Bird Survey data. Early results suggest some level of synchrony out to > 500 km, well beyond the range typical of dispersal. I hope to determine whether synchrony in agricultural practices contribute to this pattern - an ‘agricultural Moran effect’.

Spatial synchrony in Grasshopper Sparrow populations based on Breeding Bird Survey data. Early results suggest some level of synchrony out to > 500 km, well beyond the range typical of dispersal. I hope to determine whether synchrony in agricultural practices contribute to this pattern - an ‘agricultural Moran effect’.

Populations can fluctuate in synchrony over varying distances for three main reasons: 1) connection through dispersal, 2) common environmental conditions (the ‘Moran effect’), and 3) synchronous fluctuations in predators or resources. Part of my dissertation is investigating spatial synchrony in North American grassland bird populations to determine if synchrony in agricultural practices is causing an ‘agricultural Moran effect’. Synchrony among populations has implications for meta-population persistence, which may be especially relevant to grassland birds given the currently fragmented nature of their habitat.

Allen, M. A., et al. (in prep.) Shifting geographies of spatial synchrony in North American grassland birds: a window into regional population drivers and vulnerabilities. Target: Conservation Biology.