Please Advise

Anthony Zemba AZemba at
Wed Aug 23 09:27:36 EDT 2006

Hi Diane:
IN the literature, I frequently come across the general recommendations
for mowing anytime after August 1 to avoid direct impact to unfledged
young of grassland birds, however if the grassland contains a population
of grassland birds that have produced young, they may be fledged by Aug.
1st but may still be dependent upon a grassland with a more complex
structural diversity and floristic composition than a mowed field for
both cover and food, therefore mowing even after they are fledged could
have indirect impact. In my experience with grassland bird restoration,
annual mowing, even after Aug. 1st is generally NOT beneficial to
grassland birds, especially if those species are meadowlarks and
bobolinks, which tend to prefer more mature grasslands. Rotational
mowing (mowing alternating patches on different years) is often
recommended, but even this may not be necessary on an annual basis. THe
bobolink populations that I have monitored seem to do well in landscapes
that have fields that have not been mowed for a number of years adjacent
to fields supporting annuals grasses. Developing a mowing plan for a
grassland depends on factors such as soil type (low fertility soil
usually maintains grasslands in early seral states longer than higher
fertility soils) moister regime, species composition of the grassland or
meadow, and the target species of grassland birds (as some grassland
birds prefer sparsely vegetated grasslands, while others prefer densely
vegetated grasslands. In addition, some grassland birds tolerate a
higher percentage of shrub coverage, and certain shrubs may even provide
the special habitat attributes often overlooked in grassland bird
restoration/mitigation projects. For instance some monitored Savannah
Sparrow populations were found to tolerate shrub coverages of up to 35%.

Grassland successional stages usually progress as follows (from Payne
and Bryant 1994):

bare soil;
annual plants (both grasses and forbs);
perennial forbs;
short-lived perennial grasses;
sod-forming grasses or bunchgrasses (the latter states dependent upon
the physiography of the site);

Therefore, the longer a field matures, the more compliment of flowering
forbs to provide nectar sources for lepidoptera, and more forb foliage
for grazing lepidoptera larvae, many of which as you know provide food
to grassland birds. Now of course the ecology of grassland management is
way too complex for me to sum up in this one e-mail so please call me
for references and citations to the information I provided above and to
discuss further as you wish. Without knowing the site, the target
grassland bird species, the plant community composition, soil type and
other factors, it is hard to even begin to suggest management goals for
any given site.

Anthony J. ZembaSenior EcologistPlanning and Environmental Compliance
Maguire Group Inc.One Court StreetNew Britain, CT 06051
p: (860) 224-9141 ext. 236f: (860) 224-9147Azemba at


Payne, Neil F. and Bryant, Fred C. 1994. Techniques for Wildlife
Habitat Management of Uplands. McGraw-Hill, Inc. 1994. 552pp.


>>> <dianetucker01 at> 8/22/2006 5:45 PM >>>
I am curious to know what recommendations butterfly experts have
concerning the mowing of fields and grasslands and the effect on
butterflies and other insects. The wisdom on mowing to attract and
maintain grassland birds is that mowing anytime after August 1 is OK.
Wouldn't mowing a grassy habitat with a high number of butterflies right
now affect them very negatively? Please share your wisdom with me. I
work as a naturalist but don't know a lot about this particular topic. I
am trying to find this out to head off a mass mowing at my place of
employment, which has many, many varieties of butterflies and
dragonflies. Please help! Diane Tucker

-------------- next part --------------
An HTML attachment was scrubbed...

More information about the Ctleps-l mailing list