llatu re_ of Damage 



Damage "by horned larks usually 'begins as the first plants break 

 through the surface of the soil, and it inay continue iintil the plants reach 

 a height of several inches. The horned lark nips off parts of the tender 

 plantlets, or in the case of small, weak-rooted seedlings such as lettuce, 

 it may pull up the entire plant. In any event, if nipped off "below the 

 crovm, the plantlet dies.. In more rohust kinds, such as heans, the first 

 cotyledons may he nipped off, the plant "being thus destroyed. If the seed- 

 ling is not destroyed in any early stage, secondary leaflets and adventitious 

 huds are speedily consumed as they appea.r. They are often pruned "back so 

 persistently that the plants are permanently dwarfed and as a result produce 

 no fruit or seed. 



Although the most severe attacks are usually upon tender plantlets, 

 in certain years extensive depreda.tions have occurred upon "bean and pea "blos- 

 soms late in the sijmmcr. This may "be so serious as virtually to wipe out 

 the crop in an entire district. In a few instajices horned larks have "been 

 ohserved picking the outer leaves /of head lettuce to such depth that exces- 

 sive waste was occasioned in discarding the perforated leaves. In one case 

 it was noted that as turnip seedlings, appos.red through the ground t'ne birds 

 literally dug up the drill-track to feed upon the germinating seeds. 



Laboratory analysis of the stomach contents of horned la.rks engaged in 

 these attacks usually fails to give an accurate idea of the damage done. 

 A certain q.uantity of the green vegetable tissue will be found in the stomachs 

 of the birds; yet in many instances it is noted that by far the major portion 

 of the plant tissue torn from the plantlets is dropped on the ground: further- 

 more, many plantlets may.be pulled up or broken off and left without any 

 evidence of the removal of any of the leaflets. Probably depredations upon 

 green crop plants result from a search for moisture. 



On dry-farmed areas, where plant growth is slow, the damage may extend 

 over a long period and thus ca-use excessive loss. In irrigated fields, where 

 the plants grow rapidly, the attack is us-'oally of relatively short duration. 

 On the other hand, irrigation of fields in an otherwise arid area and without 

 green vegetation may cause an abnormal concentration of birds, resulting in 

 severe losses. 



The first evidence of damage by horned larks is usually the-.donuding of 

 pXanta -f rora a small- area near the center of a field, distant from cover or 

 fences. As the attack continues the bare spot ma,y spread with startling 

 rapidity, until in severe depredations only a narrow fringe of undamaged plants 

 may remain about the borders of the field. 



Season of Damage 



In general, attacks by horned larks upon crops are closely correlated 

 with the dry season. Most of the depredations occur after the natural vege- 

 tation of the surrounding range or grassland has dried up, and they may 

 continue until the first fall rains come. Because of the great variation 

 in conditions within the Sta.te, one can say only that the greater part of 

 the damage occurs between mid-June and ITovember. 



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