ORNITOLOGIA NEOTROPICAL 15 (Suppl.): 301–307, 2004
© The Neotropical Ornithological Society
TINAMOUS AND AGRICULTURE: LESSONS LEARNED FROM
Jeffrey J. Thompson
Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia
30602-2152, USA. E-mail: email@example.com
Resumen. – Tinámidos y agricultura: lecciones aprendidas de los Galliformes. – El 32% de las 47
especies del orden Tinamiformes viven en pastizales. Estas especies están distribuidas en las regiones tro-
picales y templadas, pero la mayoría se encuentran en las regiones australes de América del Sur. Las pobla-
ciones de estas especies son susceptibles a la conversión de la tierra para agricultura y la intensificación del
uso de la tierra después de la conversión. Existe poca infor mación sobre los efectos de la conversión y
uso de la tierra en las poblaciones de tinamúes, pero hay mucha investigación sobre sus efectos en los
Galliformes. Al considerar los tinamúes que viven en pastizales como los equivalentes ecológicos de
los Galliformes, se pueden hacer inferencias generales sobre los posibles efectos de la conversión y inten-
sificación del uso de la tierra en estas especies. Es más eficiente ver los impactos potenciales del uso de
la tierra como una función de la interacción de múltiples gradientes: el área de la vegetación natural, la
estructura de la vegetación, la intensidad de la agricultura y ganadería, y el uso de herbicidas y pesticidas.
Este modelo permite una cuantificación de la conveniencia de un lugar para cada especie, flexibilidad
potencial de las especies a los cambios de hábitat, la comparación entre lugares y funciona como una
herramienta para determinar rápidamente el valor de conservación de los lugares en el paisaje.
Abstract. – Species inhabiting grassland and steppes represent 32% of the 47 species of the order Tinami-
formes. These species are both tropical and temperate in their distribution but the majority is confined to
austral South America. Populations of these species are susceptible to land conversion for agriculture, as
well as intensification of land use after conversion. Although little information exists on the effects of land
conversion and use on tinamou populations, there is an extensive amount of research on these effects on
gallinaceous birds. By viewing the grassland and steppe dwelling tinamous as ecological equivalents to the
Galliformes, general inferences can be made about the projected impacts of land conversion and the inten-
sity of use on these species. It is most efficient to view the potential impacts of land use as a function of
the interaction of several gradients: area of natural vegetation, vegetation structure, intensity of cropping
and grazing, and herbicide and pesticide use. This model allows for a quantification of site suitability by
species, potential resilience of species, comparison among sites, and serves as a tool to rapidly assess the
conservation value of sites within the landscape. Accepted 29 December 2003.
Key words: Tinamiformes, Galliformes, agriculture, grazing, agro-ecosystems, grasslands, gamebirds.
Temperate and tropical grassland habitats
(grasslands, steppes, savannas) have been, and
continue to be, extensively converted for
grazing and row crops (from here on agricul-
ture) (White et al. 2000). Consequently, much
of the biodiversity from these natural ecosys-
tems is now associated with a landscape
matrix of varying complexity, consisting of
natural and man modified habitats. Increas-
ingly, these agro-ecosystems have become less
diversified in content and complexity
(McNeely et al. 1995).
During the post-World War II era, grass-
land conversion and/or agricultural intensifi-
cation have increased in intensity and extent
(Fuller 2000). Although Europe and North
America have been placed under high-input
agriculture over the last half-century, other
areas such as South Africa and Argentina
have lagged behind until recently (Pero &
Crowe 1996, Viglizzo & Roberto 1998). This
process of land conversion and agricultural
intensification has been attributed to the glo-
bal declines of grassland and shrubland birds
(Aebischer et al. 1999, Vickery & Herkert
1999, Murphy 2003, Peterjohn 2003).
Among the grassland dependent birds, the
population declines of the gallinaceous game-
birds were some of the first to draw the atten-
tion of researchers and the public. The first,
and one of the most thorough studies into the
effects of farmland composition and manage-
ment on galliform populations was on the
declines of the Grey Partridge (Perdix perdix)
in England (Potts 1980, 1986). This research
highlighted the importance of the composi-
tion and configuration of the agricultural
landscape and how it is managed, particularly
the use of herbicides and pesticides. These
have become major themes in the research of
grassland birds (Vickery & Herkert 1999,
Aebischer et al. 2000, Murphy 2003, Peterjohn
2003) and have been key topics of research
for many gamebirds (Rands et al. 1988),
including Northern Bobwhite (Colinus virgi-
nianus; Brennan 1999), prairie chickens (Tym-
panuchus spp.; Fuhlendorf et al. 2002, Geisen
1998, Ryan et al. 1998), Helmeted Guineafowl
(Numida meleagris; Pero & Crowe 1996, Malan
& Benn 1999, Ratcliffe & Crowe 2001) and
francolins (Fra n colin us spp.; Little & Crowe
1998; Jansen et al. 1999, 2000).
Grassland tinamous (Tinamiformes) rep-
resent 32% of the 47 species and, in most of
South America, occupy the majority of niches
in grassland habitats associated with the galli-
forms in other regions (Davies 2002, del
Hoyo 1992 et al.). Despite their diversity and
importance in sport, commercial, and subsis-
tence harvest, little research has focused on
these birds. Furthermore, as in the rest of the
world, the grassland habitats that these birds
occupy have been, and continue to be, under
intensive agricultural pressure. For example,
the pampas of Argentina and Uruguay have
been nearly completely converted to row
crops and grazing over the last 150 years (Hall
et al. 1992), and for the past decade have been
subjected to rapidly increasing intensification
(Viglizzo & Roberto 1998).
Despite this continuing land conversion,
and increasingly intense utilization, there is a
conspicuous lack of research into their effects
on biodiversity in grassland ecosystems within
South America. For tinamous however, it is
possible to make inferences based upon the
extensive body of research into the impacts of
land conversion and agriculture on galliforms.
Here I draw from examples on the effects of
agricultural land conversion and intensifica-
tion on grassland bird species in general, and
galliforms in particular, highlighting the major
environmental gradients that impact these
birds, for the purpose of assessing the quality
of grasslands and their associated agro-eco-
systems for tinamous, as well as to direct
CASES IN THE GALLIFORMES
Due to their importance as gamebirds, the
Galliformes are a well-studied order and sub-
sequently population dynamics are well docu-
mented for many species (e.g., Fuller et al.
2000). Over the last half-century however, as
with many grassland species, galliforms asso-
ciated with grasslands and agro-ecosystems
have exhibited significant population declines
TINAMOUS AND AGRICULTURE
across several continents. Important examples
are the Northern Bobwhite (Brennan 1999)
and prairie chickens (Johnsgard 1983, Hous-
ton 2002) in North America, the Helmeted
Guineafowl (Pero & Crowe 1996, Malan &
Benn 1999, Ratcliffe & Crowe 2001) and the
francolins (Little et al. 1995; Jansen et al. 1999,
2000) in South Africa, and the Gray Partridge
in Europe (Potts 1980, 1986).
The decline of populations of these spe-
cies is mostly attributed to changes in the
extent, intensity, and type of land use. Inter-
estingly, several of these species initially
increased their ranges and/or populations as a
function of anthropogenic changes to the
landscape. These changes, however, eventu-
ally passed a threshold where populations
began to decline. The key to making infer-
ences to the tinamous and applying them for
research and management is to understand
the major factors associated with land use that
have both positively and negatively impacted
galliform populations in grasslands and agro-
ecosystems (Johnsgard & Wood 1968, Johns-
gard 1983, Johnson & Knue 1989, Pero &
Crowe 1996, Brennan 1999, Malan & Benn
1999, Ratcliffe & Crowe 2001, Houston
As discussed by Fuller (2000), the intensifica-
tion in agriculture that has occurred has been
largely due to increased mechanization, the
use of chemical fertilizers, pesticides and her-
bicides, and decreased diversity of crop types.
Mechanization allows for the cultivation of
more area and larger fields, the large-scale
application of fertilizers, pesticides and herbi-
cides, and more frequent tilling or cutting of
hedgerows and field borders.
The use of fertilizers eliminates the need
to leave fields fallow or in pasture, eliminates
the need for manure, thus eliminating the
need for cattle and associated pastures, and
has led to the management of pastures for
silage rather than for hay. The increase in
management for silage allows for higher
stocking levels of livestock since forage can be
subsidized with high quality fodder. High live-
stock densities have been contributing to
decreases in populations of several galliform
species (Jansen et al. 1999, Robbins et al.
2002). Furthermore, mechanization has
allowed for more frequent cutting of these
pastures for silage, leading to increased loss of
nests and young.
The use of petrochemicals, associated
with the decrease in landscape complexity and
diversity, had major implications for popula-
tions of birds in agro-ecosystems due to
impacts on brood survival (Palmer 1995,
Fuller 2000). In particular, the indirect effects
of herbicides and the direct effects of insecti-
cides greatly decrease the quality of agricul-
tural land as brood habitat, and subsequently
brood survival (sensu Potts 1986). Further-
more, the use of fertilizers on silage pastures
leads to a decrease in floral diversity and
structure, and is associated with a decrease in
invertebrate diversity (Fuller 2000).
ASSESSING THE AGRICULTURAL
The aforementioned factors interact synergis-
tically to decrease the complexity and the
diversity of the landscape and the quality of
habitats within the landscape. Although the
degree to which each factor interacts to affect
a species is species dependent, these factors
can be generalized into several principal gradi-
ents, each consisting of several components.
These gradients are: 1) pesticide and herbicide
use, 2) vegetation structure, 3), intensity of
land use, and 4) area of natural vegetation (i.e.,
not being managed for row crops or silage).
Pesticide and herbicide use includes chem-
ical strength, amount applied, and frequency
of application. Vegetation structure includes
measures of height, density, and species diver-
sity. Intensity of land use is represented by
field size, crop diversity, crop rotation, and
livestock densities and grazing rotations. Area
of natural vegetation not only includes graz-
ing and fallow land, but vegetation and crop
stubble within row crops. The intensity of
land use and area of natural vegetation
together represent a measure of landscape
composition that has been illustrated to be
important for many galliforms (Potts 1986,
Aebischer & Potts 1998, Malan & Benn 1999,
It is necessary to realize that the impor-
tance that each of these gradients has for a
species will not only depend upon the species
but upon the temporal needs of individuals
and, subsequently, dietary and habitat require-
ments need to be assessed for all stages of a
species life cycle. This is particularly impor-
tant since agro-ecosystems are dynamic envi-
ronments, and subsequently need to be
assessed and measured at regular intervals
throughout the year.
These gradients act synergistically to
impact populations, but it can be hypothe-
sized that there are two general responses that
can be expected based upon the aforemen-
tioned examples, with the magnitude of the
response dependent upon the species (Fig. 1).
The first is where populations initially
increase as a function of cultivation and/or
grazing, when not intensive or extensive;
however, populations begin to decline rapidly
after the combined effects of the gradients
pass a certain magnitude (Fig. 1a). Such popu-
lation responses have been documented for
Helmeted Guineafowls (Pero & Crowe 1996)
and Greater Prairie-Chickens (Tympanuchus
cupido; Johnsgard & Woods 1968, Johnsgard
FIG. 1. Graphical model of the effects of increasing agricultural intensification on grassland Galliformes.
This may also serve as a model for grassland tinamous in South America.
TINAMOUS AND AGRICULTURE
1983, Johnson & Knue, 1989, Houston 2002).
The second response is where populations
remain stable despite initial land conversion
and management but, as in the first example,
decline after the combined impacts of the gra-
dients reach a certain threshold (Fig. 1b). This
response has been evident with the popula-
tion declines of the Northern Bobwhite in the
United States, associated with land conversion
in the 19th and early 20th centuries (Brennan
1999), and with the Redwing Francolin (Fran-
colinus levaillantii) stemming from over grazing
(Jansen et al. 1999).
To successfully apply this model to the con-
servation and management of tinamous in
agricultural landscapes there needs to be
quantitatively rigorous population estimation
of species along various intensities of each of
the proposed gradients (sensu Conroy & Car-
roll 2001). This will allow for an assessment
of the impacts of different land use regimes
on populations and provide baseline data to
assess long term population trends.
Such research only yields the effects of
land use; however, and given the small
amount of information on tinamou biology,
research needs to concentrate on understand-
ing the mechanisms that drive population
dynamics by researching the basic biology of
each species throughout the year. Moreover, if
the model of Galliformes as an inference
holds true, there should be an emphasis on
understanding the reproductive biology and
the factors that affect chick survival, since
these appear to be key factors in determining
population size (Potts 1980, 1986, Palmer
Given the rapid and continued conversion
of grassland systems to agriculture through-
out South America and the intensification of
that agriculture, there looms a growing crisis
for the conservation of biodiversity within
these systems. As pointed out by Jansen et al.
(1999), gallinaceous gamebirds can serve as
excellent indicators of ecosystem health.
Given that tinamous serve as ecological
equivalents to the galliforms, research into the
effects of land use will not only serve to con-
serve and guide management of these species,
but will contribute to conservation of the
increasingly threatened biodiversity associated
with South American grasslands and agro-
This presentation and the organization and
attendance of the symposium “Ecology and
Conservation Status of the Tinamiformes” at
the VII Neotropical Ornithological Con-
gress, Termas de Puyehue, Chile was partially
made possible through funding from the
American Pheasant and Waterfowl Society
and the Graduate School of the University of
Georgia. This manuscript was improved by
comments from John P. Carroll.
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