Movement studies in the Rufous ,

Gomphocerippus rufus (L.)

Stefan Opitz

Institute of Ecology

Friedrich Schiller-University Jena, Germany

Samenvatting

is het iets de aard Om de kwetsbaarheid te bepalen van populaties van een soort belangrijk te weten over grote en

haar In in klein terrein Jena werden van haar ”territorium” en dispersievermogen. een groot en een nabij (Duitsland) in 1994 en 1995 totaal ca. 350 exemplaren van de Rosse sprinkhaan voorzien van een reflecterend strookje en van

Door het konden de dieren ’s nachts worden en een schijfje met een nummer. strookje eenvoudig teruggevonden,

Het dat ”territorium” hebben zich verder hun positie op een kaart weergegeven. blijkt mannetjes een groter en

terrein beide dan in het kleine terrein. Verder bleek dat verspreiden dan vrouwtjes; in het grote waren maten groter

de dieren uit het kleine terrein zich significant meer ophouden in vegetaties met Dravik en in stukken met kruiden en struiken niet hoger dan 60 cm, terwijl stukken met hogere vegetaties of kale grond juist gemeden werden.

Résumé

Etudes sur la mobilité de rufus

l'étendue de la de La détermination de la vulnérabilité d'une espèce demande une connaissance de et nature son

site à ainsi dans site "territoire" et de sa capacité de dispersion. Dans un grande superficie que un beaucoup plus

350 de été d'un ruban petit, près de Jena (Allemagne), env. exemplaires Gomphocerippus rufus ont marqués

les facilement être durant la reflectant et d'un disque numéroté. A l'aide de ce ruban, animaux pouvaient repérés nuit, et leurs positions ont été cartographiées. Les mâles semblent avoir un "territoire" plus grand et ils se dispersent

les distances les deux étaient sur une plus grande distance; dans le site à grande superficie parcourues par sexes plus

à dans les à herbes grands. En outre, les animaux du petit site se tenaient plus dans les végétations et parties

tandis évitées les à haute celles et buissons d'une hauteur de moins de 60 cm, qu'étaient parties végétation plus ou

sans végétation.

the Within a German wide research project "Importance of to find them in darkness quite easily by sweeping isolation, habitat size and habitat quality for the survi- study plots with a lamp. Furthermore, a small, numbe-

the val of and plant populations on dry grasslands" red plastic disc was glued on pronotum to recognise

From the middle of studies on mobility and habitat use of the Rufous grass- individually. August

observation of hopper (Gomphocerippus rufus (L.)) have been under- (marking date) until November (last a taken at Mesobrometum plots south of Jena/Thuringia. marked grasshopper) the study plots were checked by

third in Movement data provide qualitative and quantitative night (once a week in 1994, every night 1995).

that devided references about habitat requirements of this species. Observations were registered using a map

and their habi- the habitat in 5 5 This is important to protect populations x m quadrats. tats. Furthermore these studies contribute to population The studies on mobility were focused on linear and

vulnerability analyses. spatial movement parameters. Dispersal range - a

of time - informa- linear parameter long mobility gives

of of studied The research was carried out during the summer and tions about the ability local dispersal

autumn of 1994 and 1995 at two Mesobrometum plots populations (Kohler, 1996; Samietz et al., 1996).

in the nature reserve "Leutratal" south of Jena. Both Individuals with at least 4 observations were used to

calculate the distance plots are inclined 14—35° to the south and distinguis- dispersal ranges, being largest

2 2 hed by their different sizes (3100 m and 700 m ). between the observation points of an individual. Home

65 and - - the area of To investigate movement parameters, between range a spatial parameter means activity

within the habitat. At least 5 observati- 100 individuals were marked and released on each plot a grasshopper

the criteria for home both in 1994 and 1995. Small pieces of reflection tape ons per grasshopper was range were fixed on the hind tibiae of the adults. This enables calculations. Two methods - convex polygon (Hayes,

Saltabel 16 19 and harmonic mean & - low values of 1949) (Dixon Chapman, 1980) Relatively dispersal range and home

were used to determinethis parameter based on obser- range showed a considerable philopatry of G. rufus

vation points (Table 1). within the studied plots. This concurs with most of the

Results were evaluated regarding the individual diffe- other grasshopper species studied (summery in Ingrisch

rences in both sexes. Additionally, the dependence of & Kohler, 1997). Biotic and abiotic factors like plot

well environ- size seemed influence the mobility on population density as as on to movement parameters.

mental like habitat size and climatic condi- parameters Indirectely, the observation points gave informations

tions have been considered. about the habitat structures the grasshoppers prefer.

Nevertheless, differentresults at different plots indica-

of The first results showed that the medians dispersal ted a high degree of habitat specifity. Comparable

and home in males than in fe- studies Stenobothrus lineatus the range range are larger on at same study area

males (Table 1). The comparison between the two showed differences in habitat utilization. Whereas G.

study plots in 1994 showed higher values for the larger rufus prefer structures with Bromus erectus as well as

plot. The considerable differences in the dispersal herbs and shrubs up to 60 cm height, S. lineatus signi-

and home between 1994 and 1995 for the avoid of ranges ranges ficantly herbs and shrubs more than 30 cm

smaller study plot could be a methodical artifact caused height. The habitat utilization of S. lineatus is closely by the much higher observation frequency in 1995, but related to the distributionof Bromus tussocks (Samietz,

climatic differences between those years might be 1996). Contrary to the broader structural niche of G. another possible cause and checking still needs to be rufus, S. lineatus shows a higher specialization with

done. The values for the large plot in 1995 are still not regard to habitat structures. available.

The results information about References present only partly give

of studied There still K.R. & J.A. 1980. the mobility the species. are Dixon, Chapman, Harmonic mean

unanswered questions about movement of larvae and measure of animal activity areas. — Ecology immature adults, factors about which little is known. 61: 1040-1044.

distance travellers found. There is 1949. Calculation of of Long have not been Hayne, D.W., size home range

no idea about their existence and the potential ability of — Journal of Mammalogy 39: 190—206.

G. rufus to colonise new habitats or about the gene Ingrisch, S. & G. Kohler, 1997. Die Heuschrecken

flow between populations. Mitteleuropas. — Westarp Wissenschaften,

Magdeburg.

To of G. 1996. get references about habitat use rufus within Kohler, G., The ecological backround of popula- their study plots, the correlation was studied between tion vulnurability in central European gras- the distribution of observed grasshoppers and certain shoppers and bush crickets: A brief review. habitat The of C. structures. percentage coverage Bromus In: Settele, J., Margules, P. Poschlod &

erectus Brachypodium pinnatum, herbs and shrubs less K. Henle (eds). Species survival in fragmen- ,

than 30 cm height, herbs and shrubs of heights between ted landscapes: 290—298. — Kluwer Acade-

30 and 60 cm, herbs and shrubs of more than 60 cm mic Publishers, Dordrecht.

height and open soil patches were estimated for each Samietz, J., 1996. Zur Mikrohabitatnutzung einer Heu-

2 25 m -quadrat of the study plots. Whereas no correlati- schreckenart im Halbtrockenrasen: Stenobo- on was found at the large plot, results at the small one thrus lineatus (PANZER) (Insecta: ).

are different. Here the distribution of the observed — Verhandlungen der Gesellschaft fur Okolo- male and female grasshoppers is highly positively gie 26: 570-572.

correlated with the coverage of Bromus erectus, herbs Samietz, J., U. Berger & G. Kohler, 1996. A populati- and shrubs up to 60 cm height, and negatively correla- on vulnurability analyses of the stipe- ted with open soil patches and herbs and shrubs of winged grasshopper, Stenobothrus lineatus more than 60 cm height (Table 2). (Caelifera: ). In: Settele, J., C.

Margules, P. Poschlod & K. Henle (eds).

20 Saltabel 16 Species survival in fragmented landscapes: Dordrecht.

299—311 — Kluwer Academic Publishers,

Table 1: Median values of dispersal range and home range of G. rufus. Numbers of individuals are printed in

parentheses; bold numbers indicate statistical significance between males and females (p<0.05)

2 dispersal range [m] home range [m ]

convex polygon harmonic mean

male female male female male female

1994 large plot 20 (13) 15 (19) 111 (12) 58 (16) 308 (12) 136 (16)

small plot 13 (17) 12 (20) 70 (15) 29 (19) 148 (15) 82 (19)

1995 small plot 22 (26) 17 (28) 100 (24) 60 (26) 226 (24) 180 (26)

Table 2: Correlation coefficients r (Pearson) between the distribution of G. rufus and habitat structures at

* ** *** the small plot in 1995. p<0.05; p<0.01; pcO.001; n.s. not significant.

herbs and shrubs

30cm 30 - 60cm > 60cm open soil Brachypodium Bromus <

* * *** **** ** male -0.384 0.096 n.s. 0.656 0.504 0.448 -0.334

* *** #**** # ** * female -0.307 0.198 n.s. 0.579 0.532 0.418 -0.383

Saltabel 16 21